Full Text Archive logoFull Text Archive — Free Classic E-books

Scientific American Supplement, No. 520, December 19, 1885 by Various

Part 1 out of 2

Adobe PDF icon
Download this document as a .pdf
File size: 0.2 MB
What's this? light bulb idea Many people prefer to read off-line or to print out text and read from the real printed page. Others want to carry documents around with them on their mobile phones and read while they are on the move. We have created .pdf files of all out documents to accommodate all these groups of people. We recommend that you download .pdfs onto your mobile phone when it is connected to a WiFi connection for reading off-line.

Produced by Juliet Sutherland, Don Kretz, and the Online Distributed
Proofreading Team.




Scientific American Supplement. Vol. Vol. XX, No. 520.

Scientific American established 1845

Scientific American Supplement, $5 a year.

Scientific American and Supplement, $7 a year.

* * * * *


I. ENGINEERING, ETC.--Steel Structures.--Best use of different
grades of steel.--From a paper by Mr. JAS. CHRISTIE.

Natural Gas Fuel and its Application to Manufacturing:
Purposes.--Paper read before the Iron and Steel Institute by
Mr. ANDREW CARNEGIE.--First use of the gas.--Wells near
Pittsburg.--Extent of territory underlain with gas.--Cost of
piping.--Analyses ofnatural gas.

A Gas Engine Water Supply Alarm.--1 figure.

The Water Supply of Ancient Roman Cities.--An address by
Prof. W.H. CORFIELD.--Aqueducts for the supply of
Borne.--The aqueduct bridge Pont du Gard.--The supply of
Lyons.--Construction of underground aqueducts.

Steam Engine Economy.--By Chief Engineer J. LOWE,
U.S.N.--With diagram.

The "Elastic Limit" in Metals.--Selection of wire for
suspension bridges, etc.

Prices of Metals in 1874 and 1884.--With table.

II. TECHNOLOGY.--A Method of Measuring the Absolute Sensitiveness
of Photographic Dry Plates.--By Wm. H. PICKERING.--From the
proceedings of the Academy of Arts and Sciences.

Soldering and Repairing Platinum Vessels in the
Laboratory.--By J.W. PRATT.

The Helicoidal or Wire Stone Saw invented by M.P. GAY.--With
engraving of quarry showing application of saw, and 5 figures.

Portable Prospecting Drill and Automatic Safety Gear shown at
the Inventions Exhibition.--With 2 engravings.

III. ELECTRICITY, ETC.--Electricity in Warfare.--By Lieutenant
B.A. FISKE, U.S.N.--Electrical torpedoes.--Torpedo
detecter.--Military telegraphy and telephony.--Electricity
for firing great guns.--Arrangement of wires for lights.--The
search light.--Incandescent lamps for sight
signaling.--Electrical launches.--An "electric sight".

Meucci's Claims to the Telephone.--With description of his
instrument and 10 figures.

An Electric Centrifugal Machine for Laboratories.--By ALEX.
WATT.--From paper read before the British Association.--1

Transmission of Power by Electricity.--Experiments of M.

IV. ART AND ARCHITECTURE.--Quadriga for the New House of
Parliament at Vienna.--An engraving.

Glazed Ware Finial.--With engraving.

Hotel de Ville, St. Quentin.--With engraving.

Fire Doors in Mills.--From a lecture before the Franklin
Institute by C.J. HEXAMER.

V. NATURAL HISTORY, ETC.--Preservation of Insects.

An Accomplished Parrot.

The Roscoff Zoological Laboratory.--The buildings and
rooms.--The aquarium.--Course of study.

The Muraenae at the Berlin Aquarium.--With engraving.

Metamorphosis of Arctic Insects.

VI. MEDICINE. ETC.--A Year's Scientific Progress in Nervous and
Mental Diseases.--By Prof. L.A. MERRIAM.--Report to the
Nebraska State Medical Society.

Scaring the Baby Out.

VII. MISCELLANEOUS.--Wage Earners and their Houses.--Manufacturers
as landlords.--Experiments of Pullman, Owen, Peabody, and

The Locked and Corded Box Trick, with Directions for making
the Box.--By D B. ADAMSON.--9 figures.

A Perpetual Calendar.--With engraving.

* * * * *


To remove the verdigris which forms upon the pins, the pinned insects
should be immersed in benzine and left there for a time; several hours is
generally long enough. The administration of this bath cannot be too
highly recommended for beetles which have been rendered unrecognizable by
grease, especially when dust has been mixed with the grease. This
immersion, of variable duration according to circumstances, will restore
to these insects, however bad they have become, all their brilliancy and
all their first freshness, and the efflorescences of cupric oxide will
not reappear. This preventive and curative method is also readily
applicable to beetles glued upon paper which have become greasy; plunge
them into benzine in the same way, and as the gum is insoluble in the
liquid, they remain fastened to their supports. Pruinose beetles, which
are few in number, are the only ones that benzine can alter; the others,
which are glabrous, pubescent, or scaly, can only gain by the process,
and they will always make a good show in the collection.--_A. Dubois in
Feuille des jeunes naturatistes_, March, 1885, p. 71.--_Psyche_.

* * * * *



The new House of Parliament at Vienna is known as one of the finest
specimens of pure Greek architecture erected in this century; and
throughout the entire building great pains have been taken to ornament
the same as elaborately as is consistent with good taste. The main
buildings are provided with corner pavilions, the atticas of which
project over the roofs, and these atticas and other parts of the
buildings are to be surmounted by quadrigas, one of which is shown in
the annexed cut, taken from the _Illustrirte Zeitung_. This group was
modeled by V. Pilz, of Vienna, and represents a winged goddess in a
chariot drawn by four spirited steeds harnessed abreast. She holds a
wreath in her raised right hand, and her left hand is represented as
holding the lines for guiding the horses. The group is full of expression
and life, and will add greatly to the beauty of the building to be
surmounted by it.

* * * * *

The strongest wood in the United States, according to Professor Sargent,
is that of the nutmeg hickory of the Arkansas region, and the weakest the
West Indian birch _(Rur seva_). The most elastic is the tamarack, the
white or shellbark hickory standing far below it. The least elastic and
the lowest in specific gravity is the wood of the _Ficus aurea_. The
highest specific gravity, upon which in general depends value as fuel, is
attained by the bluewood of Texas _(Condalia obovata_).

* * * * *


[Illustration: GLAZED WARE FINIAL.]

This grand 16th century finial is a fine example of French ceramic ware,
or glazed terracotta, and it is illustrated both by geometrical elevation
and a cross sectional drawing. This latter shows the clever building up
of the structure by means of a series of five pieces, overlapping each
other, and kept rigid by means of a stout wrought-iron upright in the
center, bolted on to the ridge, and strapped down on the hip pieces. Its
outline is well designed for effect when seen at a distance or from
below, and its glazed surface heightens the artistic colorings, giving it
a brilliant character in the sunlight, as well as protecting the ware
from the action of smoke and weather.--_Build. News_.

* * * * *



Among the more prominent movements of the day for the improvement of the
condition of the working men are those which are growing into fashion
with large manufacturing incorporations. Their promise lies immediately
in the fact that they call for no new convictions of political economy,
and hence have nothing disturbing or revolutionary about them. Accepting
the usages and economical principles of industrial life, as the progress
of business has developed them, an increasing number of large
manufacturers have deemed it to their interest not only to furnish shops
and machinery for their operatives, but dwellings as well, and in some
instances the equipments of village life, such as schools, chapels,
libraries, lecture and concert halls, and a regime of morals and
sanitation. Probably the most expensive investment of this sort in the
United States, if not in the world, by any single company, is that of
Pullman, on Lake Calumet, a few miles south of Chicago, an enterprise as
yet scarcely five years old. It is by no means a novel undertaking,
except in the magnitude, thoroughness, and unity of the scheme. Twenty
years ago the managers of the Lonsdale Mills, in Rhode Island, were
erecting cottages on a uniform plan and maintaining schools and religious
services for their operatives. More recent but more extensive is the
village of the Ponemah Cotton Mill, near Taftville, Conn. These are
illustrations merely of similar investments upon a smaller scale
elsewhere. But the European examples are older, such as Robert Owen's
experiment at New Lanark in Scotland, Saltaire in Yorkshire, Dollfuss'
Mulhausen Quarter in Alsace, and M. Godin's community in the French
village of Guise, which are among the more familiar instances of
investments originally made on business principles, with a view to the
improved conditions of workmen. New Lanark failed as a commercial
community through the visionary character of its founder; the Godin works
at Guise have passed into the co-operative phase within the past five
years, but Saltaire and Mulhausen still retain their proprietary business

The class of ventures of which these instances are but the more
conspicuous examples has peculiar characteristics. They differ from the
Peabody and Waterlow buildings of London, described in _Bradstreet's_
last August, from Starr's Philadelphia dwellings, and from the operations
of the "Improved Dwellings Association" of New York in these particulars:
the latter are financially a pure question of direct investment; are
mainly concerned with life among the poor of cities, and, whatever
philanthropy may be in their motive, are capable of adaptation to any
class of citizens. The former, while investments also, are composite, the
business of manufacturing being associated with that of rent collecting
and sharing its profits and losses; their field of operations is almost
invariably rural, and tenancy is restricted to the employes of the
proprietor. On the other hand, they differ from all co-operative and
socialistic communities in that they are an adaptation to existing
circumstances, propose to demonstrate no new theories of economics, are
free from all religious bonds, do not depend on any unity of opinion, and
do not touch the question of the proper distribution of wealth.

It is, of course, no new thing for owners of large factories,
particularly in country districts, to furnish tenements for their
operatives, and oftentimes it is quite indispensable that they should,
because there would otherwise be no accommodation for their workmen. What
is recent and exceptional is the spread of the belief that it pays to
make the accommodations furnished healthful, convenient, and attractive.
The sources of profit from this careful provision are these: the
proprietors have control of the territory, and are able to prescribe
regulations which keep out the saloon and disreputable characters, and at
once there is a saving in police and court and poor taxes; for the same
reason the workmen are more regular and steady in their labor, for there
is no St. Monday holiday, nor confused head and uncertain hand; the
tenants are better able to pay their rents, and when their landlord and
employer are the same person, he collects his rent out of the wages; the
superior accommodations and more settled employment act strongly against
labor strikes. It will be seen that the larger and better product of
labor is a great factor in the profitableness of such enterprises, and
that it arises from the improved character of the laborer, on the same
principle that a farmer's stock pays him best when it is of good breed,
is warmly housed, and well fed. Against the operations of the London
Peabody and Waterlow funds it has been alleged that they dispossess the
poor shiftless tenant and bring in a new class, so that they do not
improve the condition of their tenants, but afford opportunity for better
ones to cheapen the price of their accommodations. The manufacturing
landlord cannot wholly do this, because the first thing he has to
consider is whether the applicant for a dwelling is a good workman, not
whether he can be trusted for his rent. His labor he must have. His
outlook is to make that labor worth more to him, by placing it in the
best attainable surroundings. Can this be done? If so, the ends of
humanity are answered as well as the purse filled, for both interests

Mr. Pullman, who founded the enterprise on Calumet Lake, has uttered
sentiments like these, and has proved that in this instance it does pay
to make his workmen's families comfortable, and secure from sickness and
temptation. As a financial operation Pullman is profitable. There are now
1,700 dwellings, either separate or in apartment houses, in this town,
where five years ago the prairie stretched on every side unbroken. Every
tenement is connected with common sewerage, water, and gas systems, in
which the most scientific principles and expert skill have been applied.
The price of tenements ranges from $5 per month for two rooms in an
apartment house to $16 for a separate dwelling of five rooms; but there
is a different class of houses for clerks, superintendents, and
overseers. The average price per room is $3.30 a month, or nearly twelve
per cent. higher than in Massachusetts manufacturing towns, where it is
$2.86. Taking each tenement at an average of three rooms, this rate will
pay six per cent. on an investment of $3,140,000, without taking into
account taxes and repairs, or say six per cent. on $3,000,000. But one
source of profit of great moment must not be overlooked, and it is the
appreciation of real estate by the increase of population. This is a
small factor in a great city, at least so far as concerns the humbler
grade of dwellings, but in the country it is enormous. A tract of land
which has been a farm becomes a village of from 1,000 to 10,000
inhabitants. Its value advances by leaps and bounds.

At Pullman, in addition to the shops and dwellings, there are trees and
turf-bordered malls and squares, a church, a theater, a free library with
reading rooms, a public hall, a market house, provided at the expense of
the company. Liquor can only be sold at the hotel to its guests, and then
under restrictions. There is a system of public schools under a board of
education, which is about the only civic organization, strictly speaking,
in the community. One man suffices for police duty, and he made but
fifteen arrests in the last two years. It is reported that the death rate
so far, including the mortality from accidents, has been under seven in
1,000 per annum. In Great Britain the rate is a small fraction over 22 in
1,000. The vital statistics of the United States show a smaller mortality
than this, but they are rendered abnormal by the heavy immigration which
pours into the country. Emigrants are, in the language of insurance men,
a selected class. They are usually at the most vigorous time of life and
of hardiest and most enterprising spirit.

They leave behind them the very young and the old and those enfeebled by
disease or habits. To this cause must be attributed in part the
exceptional record of Pullman in death rate, as it is a new town. Yet
there can be no question that the sanitary conditions of the place are
excellent. It is difficult in mixed enterprises of this nature to tell
what the rate of profit upon the tenement part of the business is, since
the rental and the factory react upon each other; but in the American
instances quoted in this article the investment as a whole is
remunerative. In the Godin operations at Guise, which have been
co-operative for the last five years, the capital is put at $1,320,000,
and the net earnings have averaged during that time $204,640 per annum,
or 151/2 per cent.

At Pullman a demand has arisen on the part of the tenants for a chance to
acquire proprietorship in their homes; and while the company has withheld
the privilege from its original purchase of 3,500 acres, it has bought
adjoining land, where it offers to advance money for building, and to
take pay in monthly installments. This assimilates so much of the
enterprise to that at Mulhausen, and shows the drift toward a
co-operative phase of capital and labor. Indeed, this tendency will
probably prove to be strongly characteristic of all similar schemes as
fast as they attain to any magnitude. Tendencies which can be resisted in
communities of few hundreds become overpowering when the population rises
into thousands. But from the purely commercial point of view, this drift
is hardly to be deprecated, so long as the operation of selling houses
returns the capital and interest safely.

Projects of this nature go far toward modifying the stress of antagonisms
between labor and capital, because if they are successful these are
harmonized to an appreciable extent, and this gives public interest to
them. The eventual adjustment must come, not from convictions of duty,
doctrinaire opinions, or sentiments of sympathy, but on business
principles, and it is a sure step in advance to show that self-interest
and philanthropy are in accord. How great the field for experiments of
this nature is in the United Spates may be gathered from the census of
1880, which shows 2,718,805 persons employed in the industrial
establishments of the country, with an annual production of
$5,842,000,000, and a capital of nearly half that amount. Of these hands
and values nearly two-thirds belong to the north Atlantic

* * * * *


This charming building has an uncommonly well-designed facade,
picturesque in the extreme, rich in detail, and thoroughly dignified. We
are indebted to M. Levy, of Paris, for the loan of M. Garen's spirited
etching, from which our illustration is taken. The arcaded piazza on the
ground story, the niche-spaced tier of traceried windows on the first
floor, the flamboyant paneled cornice stage, and the three crowning
gables over it unite in one harmonious conception, the whole elevation
being finished by a central tower, while at either end of the facade two
massively treated buttresses furnish a satisfactory inclosing line, and
give more than a suggestion of massiveness, so necessary to render an
arcaded front like this quite complete within itself; otherwise it must
more or less appear to be only part of a larger building. The style is
Late Gothic, designed when the first influence of the Early Renaissance
was beginning to be felt through France as well as Belgium, and in
several respects the design has a Flemish character about it.

[Illustration: HOTEL DE VILLE, ST. QUENTIN.]

St. Quentin is situated on the Goy, in the department of Cotes du Nord,
and the town is seated in a picturesque valley some ten miles S.S.W. of
the capital, St Brieuc, which is a bishop's see, and has a small harbor
near the English Channel, and about thirty miles from St.
Malo.--_Building News_.

* * * * *


[Footnote: From a lecture before the Franklin Institute by C. John

There are few parts in fire construction which are of so much importance,
and generally so little understood, as fire doors. Instances of the
faulty construction of these, even by good builders and architects, may
daily be seen. Iron doors over wooden sills, with the flooring boards
extending through from one building to the other, are common occurrences.
We frequently find otherwise good doors hung on wooden jambs by ordinary
screws. Sliding doors are frequently hung on to woodwork, and all
attachments are frequently so arranged that they would be in a very short
time destroyed by fire, and cause the door to fall. In case of fire, a
solid iron door offers no resistance to warping. In an iron lined door,
on the contrary, the tendency of the sheet iron to warp is resisted by
the interior wood, and when this burns into charcoal, it still resists
all warping tendencies. I have seen heavily braced solid iron doors
warped and turned after a fire, having proved themselves utterly
worthless. It is needless to say that when wooden doors are lined, they
should be lined on both sides; but frequently we find so-called fireproof
doors lined on one side only.

Good doors are frequently blocked up with stock and other material, so
that in case of fire they could not be closed without great exertion; or
they have been allowed to get out of order, so that in case of fire they
are useless. This has been so common that it has given rise to the
jocular expression of insurance men, when they are told that a fire door
exists between the two buildings, "Warranted to be open in case of fire."
The strictest regulations should exist in regard to closing the fire
doors nightly. Frequently we find that although the fire door, and its
different parts, are correctly made, there are openings in the wall which
would allow the fire to travel from one building to the other, such as
unprotected belt and shaft holes. That a fire door may be effective, it
must be hung to the only opening in the wall.

The greatest care must be exercised to keep joists from extending too far
into the wall, so as not to touch the joists of the adjacent building,
which would transmit the flames from one building to the other in case of
fire. A good stone sill should be placed under the door, and the floor
thereby entirely cut. Sills should be raised about one and a half inches
above the level of the floor, in order to accomplish the necessary
flooding of the same. If stock must be wheeled from one building to the
other, the sill can be readily beveled on both sides of the wall,
allowing the wheels to pass readily over it. Lintels should consist of
good brick arches. When swing doors are used, they should be hung on good
iron staples, well walled into the masonry, and the staples so arranged
that the door will have a tendency to close by its own weight. The door
should consist of two layers of good one and a quarter inch boards,
nailed crosswise, well nailed together and braced, and then covered with
sheet iron nailed on, or if of sheet tin, flanged, soldered, and nailed.
Particular care should be taken to insert plenty of nails, not only along
the edge of the door, but crosswise in all directions. I have seen cases,
where the entire covering had been ripped off through the warping
tendencies of the sheet iron.

The hinges on these doors should be good strap hinges, tightly fastened
to the door by bolts extending through it, and secured by nuts on the
other side. Good latches which keep the door in position when closed
should always be provided. In no case should the door be provided with a
spring lock which cannot be freely opened, as employes might thereby be
confined in a burning room.

Sliding doors should be hung on wrought iron runways, fastened tightly to
the wall. Wooden runways iron lined, which we frequently see, are not
good, as the charring of the wood in the interior causes them to weaken
and the doors to drop. Runways should be on an incline, so that the door
when not held open will close itself. Care must be taken to have a stop
provided in the runway, so that the doors may not, as I have frequently
seen them, overrun the opening which it is to protect. Doors should
overlap the edges of the openings on all sides. Large projecting jambs
should never be used.

All doors contained in "fire walls" should have springs or weights
attached to them, so as to be at all times closed. Fire doors can be shut
automatically by a weight, which is released by the melting of a piece of
very fusible solder employed for this purpose. So sensitive is this
solder that a fire door has been made to shut by holding a lamp some
distance beneath the soldered link and holding an open handkerchief
between the lamp and link. Though the handkerchief was not charred, hot
air enough had reached the metal to fuse the solder and allow the
apparatus to start into operation.

These solders are alloys more fusible than the most fusible of their
component metals. A few of them are: Wood's alloy, consisting of:
cadmium, 1 to 2 parts; tin, 2 parts; lead, 4 parts; bismuth, 7 to 8

This alloy is fusible between 150 deg. and 159 deg. Fahr. The fusible metal of
D'Arcet is composed of: bismuth, 8 parts; lead, 5 parts; tin, 3 parts. It
melts at 173.3 deg.. We can, therefore, by proper mixture, form a solder
which will melt at any desirable temperature. Numerous devices for
closing doors automatically have been constructed, all depending upon the
use of the fusible solder catch.

* * * * *


At a recent meeting of the Engineers' Club of Philadelphia, Mr. James
Christie presented a paper upon "The Adaptation of Steel to Structural
Work." The price of steel has now fallen so low, as compared with iron,
that its increased use will be actively stimulated as the building
industries revive. The grades and properties of the steels are so
distinct and various that opinions differ much as to the adaptability of
each grade for a special purpose. Hitherto, engineers have favored open
hearth steel on account of uniformity, but recent results obtained from
Bessemer steel tend to place either make on equality. The seeming
tendency is to specify what the physical properties shall be, and not how
the steel shall be made.

For boiler and ship plates, the mildest and most ductile steel is
favored. For ships' frames and beams, a harder steel, up to 75,000 pounds
tenacity, is frequently used. For tension members of bridges, steel of
65,000 to 75,000 pounds tenacity is usually specified; and for
compression members, 80,000 to 90,000 pounds. In the Forth Bridge,
compression steel is limited to 75,000 to 82,000 pounds. Such a marked
advantage occurs from the use of high tension steel in compression
members, and the danger of sudden failure of a properly made strut is so
little, that future practice will favor the use of hard steel in
compression, unless the material should prove untrustworthy. In columns,
even as long as forty diameters, steel of 90,000 pounds tenacity will
exceed the mildest steel 35 per cent., or iron 50 per cent., in
compressive resistance.

The present uncertainty consists largely as to how high-tension steel
will endure the manipulation usual with iron without injury. A few
experiments were recently made by the writer on riveted struts of both
mild and hard steel, which had been punched, straightened, and riveted,
as usual with iron, but no indication of deterioration was found.

Steel castings are now made entirely trustworthy for tensile working
stresses of 10,000 to 15,000 pounds per square inch. In some portable
machinery, an intermittent tensile stress is applied of 15,000 pounds,
sometimes rising to 20,000 pounds per square inch of section, without any
evidence of weakness.

* * * * *

Equal volumes of amyl alcohol (rectified fusel oil) and pure concentrated
hydrochloric acid, shaken together in a test tube, unite to form a single
colorless liquid; if one volume of benzine (from petroleum) be added to
this, and the tube well shaken, the contents will soon separate into
_three_ distinct colorless fluids, the planes of demarkation being
clearly discernible by transmitted light. Drop into the tube a particle
of "acid magenta;" after again shaking the liquids together, the lower
two zones will present different shades of red, while the supernatant
hydrocarbon will remain without color.

* * * * *


[Footnote: From the Proceedings of the Academy of Arts and
Sciences.--_Amer. Jour._]


Within the last few years the subject of dry plate photography has
Increased very rapidly, not only in general popularity, but also in
importance in regard to its applications to other departments of science.
Numerous plate manufacturers have sprung up in this country as well as
abroad, and each naturally claims all the good qualities for his own
plates. It therefore seemed desirable that some tests should be made
which would determine definitely the validity of these claims, and that
they should be made in such a manner that other persons using instruments
similarly constructed would be able to obtain the same results.

Perhaps the most important tests needed are in regard to the
sensitiveness of the plates. Most plate makers use the wet plates as
their standard, giving the sensitiveness of the dry plates at from two to
sixty times greater; but as wet plates vary quite as much as dry ones,
depending on the collodion, condition of the bath, etc., this system is
very unsatisfactory. Another method, employed largely in England, depends
on the use of the Warnerke sensitometer. In this instrument the light
from a tablet coated with luminous paint just after being exposed to a
magnesium light is permitted to shine through a colored transparent film
of graduated density upon the plate to be tested. Each degree on the film
has a number, and, after a given exposure, the last number photographed
on the plate represents the sensitiveness on an empirical scale. There
are two or three objections to this instrument. In the first place, the
light-giving power of the luminous tablet is liable to variations, and,
if left in a warm, moist place, it rapidly deteriorates. Again, it has
been shown by Captain Abney that plates sensitized by iodides, bromides,
and chlorides, which may be equally sensitive to white light, are not
equally affected by the light emitted by the paint; the bromides being
the most rapidly darkened, the chlorides next, and the iodides least of
all. The instrument is therefore applicable only to testing plates
sensitized with the same salts.

In this investigation it was first shown that the plates most sensitive
for one colored light were not necessarily the most so for light of
another color. Therefore it was evident that the sun must be used as the
ultimate source of light, and it was concluded to employ the light
reflected from the sky near the zenith as the direct source. But as this
would vary in brilliancy from day to day, it was necessary to use some
method which would avoid the employment of an absolute standard of light.
It is evident that we may escape the use of this troublesome standard, if
we can obtain some material which has a perfectly uniform sensitiveness;
for we may then state the sensitiveness of our plates in terms of this
substance, regardless of the brilliancy of our source. The first material
tried was white filter paper, salted and sensitized in a standard
solution of silver nitrate. This was afterward replaced by powdered
silver chloride, chemically pure, which was found to be much more
sensitive than that made from the commercial chemicals. This powder is
spread out in a thin layer, in a long paper cell, on a strip of glass.
The cell measures one centimeter broad by ten in length. Over this is
laid a sheet of tissue paper, and above that a narrow strip of black
paper, so arranged so as to cover the chloride for its full length and
half its breadth. These two pieces of paper are pasted on to the under
side of a narrow strip of glass which is placed on top of the paper cell.
The apparatus in which the exposures are made consists of a box a little
over a meter in length, closed at the top by a board, in which is a
circular aperture 15'8 cm. in diameter. Over this board may be placed a
cover, in the center of which is a hole 0.05 cm. in diameter, which
therefore lets through 0.00001 as much light as the full aperture. The
silver chloride is placed a distance of just one meter from the larger
aperture, and over it is placed the photographic scale, which might be
made of tinted gelatines, or, as in the present case, constructed of long
strips of tissue paper, of varying widths, and arranged like a flight of
steps; so that the light passing through one side of the scale traverses
nine strips of paper, while that through the other side traverses only
one strip. Each strip cuts off about one-sixth of the light passing
through it, so that, taking the middle strip as unity, the strips on
either side taken in order will transmit approximately--

1 2 3 4 5 6 7 8 9
2.0 1.65 1.4 1.2 1.0 0.85 0.7 0.6 0.5

The instrument is now pointed toward the zenith for about eight minutes,
on a day when there is a bright blue sky. On taking the apparatus into
the dark room and viewing the impression by gaslight, it will be found
that the markings, which are quite clear at one end, have entirely faded
out by the time the middle division is reached. The last division clearly
marked is noted. Five strips cut from sensitized glass plates, ten
centimeters long and two and a half in width, are now placed side by side
under the scale, in the place of the chloride. By this means we can test,
if we wish, five different kinds of plates at once. The cover of the
sensitometer containing the 0.05cm. hole is put on, and the plates
exposed to sky light for a time varying anywhere between twenty seconds
and three minutes, depending on the sensitiveness of the plates. The
instrument is then removed to the dark room, and the plates developed by
immersing them all at once in a solution consisting of four parts
potassium oxalate and one part ferrous sulphate. After ten minutes they
are removed, fixed, and dried. Their readings are then noted, and
compared with those obtained with the silver chloride. The chloride
experiment is again performed as soon as the plates have been removed,
and the first result confirmed. With some plates it is necessary to make
two or three trials before the right exposure can be found; but if the
image disappears anywhere between the second and eighth divisions, a
satisfactory result may be obtained.

The plates were also tested using gaslight instead of daylight. In this
case an Argand burner was employed burning five cubic feet of gas per
hour. A diaphragm 1 cm. in diameter was placed close to the glass
chimney, and the chloride was placed at 10 cm. distance, and exposed to
the light coming from the brightest part of the flame, for ten hours.
This produced an impression as far as the third division of the scale.
The plates were exposed in the sensitometer as usual, except that it was
found convenient in several cases to use a larger stop, measuring 0.316
cm. in diameter.

The following table gives the absolute sensitiveness of several of the
best known kinds of American and foreign plates, when developed with
oxalate, in terms of pure silver chloride taken as a standard. As the
numbers would be very large, however, if the chloride were taken as a
unit, it was thought better to give them in even hundred thousands.


Plates. Daylight. Gaslight.
Carbutt transparency 0.7 ..
Allen and Rowell 1.3 150
Richardson standard 1.3 10
Marshall and Blair 2.7 140
Blair instantaneous 3.0 140
Carbutt special 4.0 20
Monroe 4.0 25
Wratten and Wainwright 4.0 10
Eastman special 5.3 30
Richardson instantaneous 5.3 20
Walker Reid and Inglis 11.0 600
Edwards 11.0 20
Monckhoven 16.0 120
Beebe 16.0 20
Cramer 16.0 120

It will be noted that the plates most sensitive to gaslight are by no
means necessarily the most sensitive to daylight; in several instances,
in fact, the reverse seems to be true.

It should be said that the above figures cannot be considered final until
each plate has been tested separately with its own developer, as this
would undoubtedly have some influence on the final result.

Meanwhile, two or three interesting investigations naturally suggest
themselves; to determine, for instance, the relative actinism of blue
sky, haze, and clouds; also, the relative exposures proper to give at
different hours of the day, at different seasons of the year, and in
different countries. A somewhat prolonged research would indicate what
effect the presence of sunspots had on solar radiation--whether it was
increased or diminished.

* * * * *


[Footnote: Read before the Iron and Steel Institute of London, May 8,


In these days of depression in manufacturing, the world over, it is
specially cheering to be able to dwell upon something of a pleasant
character. Listen, therefore, while I tell you about the natural gas fuel
which we have recently discovered in the Pittsburg district. That
Pittsburg should have been still further favored in the matter of fuel
seems rather unfair, for she has long been noted for the cheapest fuel in
the world. The actual cost of coal, to such as mine their own, has been
between 4s. and 5s. per ton; while slack, which has always been very
largely used for making gas in Siemens furnaces and under boilers, has
ranged from 2s. to 2s. 6d. per ton. Some mills situated near the mines or
upon the rivers for many years received slack coal at a cost not
exceeding 1s. 6d. per ton. It is this cheap fuel which natural gas has
come to supplant. It is now many years since the pumping engines at oil
wells were first run by gas, obtained in small quantities from many of
the holes which failed to yield oil. In several cases immense gas wells
were found near the oil district; but some years elapsed before there
occurred to any one the idea of piping it to the nearest manufacturing
establishments, which were those about Pittsburg. Several years ago the
product of several gas wells in the Butler region was piped to two mills
at Sharpsburg, five miles from the city of Pittsburg, and there used as
fuel, but not with such triumphant success as to attract much attention
to the experiment. Failures of supply, faults in the tubing, and
imperfect appliances for use at the mills combined to make the new fuel
troublesome. Seven years ago a company drilled for oil at Murraysville,
about eighteen miles from Pittsburg. A depth of 1,320 feet had been
reached when the drills were thrown high in the air, and the derrick
broken to pieces and scattered around by a tremendous explosion of gas.
The roar of escaping gas was heard in Munroville, five miles distant.
After four pipes, each two inches in diameter, had been laid from the
mouth of the well and the flow directed through them, the gas was
ignited, and the whole district for miles round was lighted up. This
valuable fuel, although within nine miles of our steel-rail mills at
Pittsburg, was permitted to waste for five years. It may well be asked
why we did not at once secure the property and utilize this fuel; but the
business of conducting it to the mills and there using it was not well
understood until recently. Besides this, the cost of a line was then more
than double what it is now; we then estimated that L140,000 would be
required to introduce the new fuel. The cost to-day does not exceed
L1,500 per mile. As our coal was not costing us more than 3s. per ton of
finished rails, the inducement was not in our opinion great enough to
justify the expenditure of so much capital and taking the risk of failure
of the supply. Two years ago men who had more knowledge of the oil-wells
than ourselves had sufficient faith in the continuity of the gas supply
to offer to furnish us with gas for a sum per year equal to that hitherto
annually paid for coal until the amount expended by them on piping had
been repaid, and afterward at half that sum. It took us about eighteen
months to recoup the gas company, and we are now working under the
permanent arrangement of one-half the previous cost of fuel on cars at
work. Since our success in the use of this new natural fuel at the rail
mills, parties still bolder have invested in lines of piping to the city
of Pittsburg, fifteen to eighteen miles from the wells. The territory
underlain with this natural gas has not yet been clearly defined. At the
principal field, that of Murraysville (from which most of the gas is
obtained to-day), I found, upon my visit to that interesting region last
autumn, that nine wells had been sunk, and were yielding gas in large
quantities. One of these was estimated as yielding 30,000,000 cubic feet
in 24 hours. This district lies to the northeast of Pittsburg, running
southward from it toward the Pennsylvania Railroad. Gas has been found
upon a belt averaging about half a mile in width for a distance of
between four and five miles. Beyond that again we reach a point where
salt water flows into the wells and drowns the gas. Several wells have
been bored upon this belt near the Pennsylvania Railroad, and have been
found useless from this cause. Geologists tell us that in this region a
depression of 600 feet occurs in the strata, but how far the fault
extends has not yet been ascertained. Wells will no doubt soon be sunk
southward of the Pennsylvania Railroad upon this half-mile belt. Swinging
round toward the southwest, and about twenty miles from the city, we
reach the gas fields of Washington county. The wells so far struck do not
appear to be as strong as those of the Murraysville district, but it is
possible that wells equally productive may be found there hereafter.
There are now four wells yielding gas in the district, and others are
being drilled. Passing still further to the west, we reach another gas
territory, from which manufacturing works in Beaver Falls and Rochester,
some twenty-eight miles west of Pittsburg, receive their supply.
Proceeding with the circle we are drawing in imagination around
Pittsburg, we pass from the west to the southwest without finding gas in
any considerable quantity, until we reach the Butler gas field,
equidistant from Pittsburg on the northwest, with Washington county wells
on the southwest. Proceeding now from the Butler field to the Allegheny
River, we reach the Tarentum district, still about twenty miles from
Pittsburg, which is supplying a considerable portion of the gas used.
Drawing thus a circle around Pittsburg, with a radius of fifteen to
twenty miles, we find four distinct gas-producing districts. In the city
of Pittsburg itself several wells have been bored; but the fault before
mentioned seems to extend toward the center of the circle, as salt water
has rushed in and rendered these wells wholly unproductive, though gas
was found in all of them.

I spent a few days very pleasantly last autumn driving with some friends
to the two principal fields, the Murraysville and the Washington county.
In the former district the gas rushes with such velocity through a 6-inch
pipe, extending perhaps 20 feet above the surface, that it does not
ignite within 6 feet of the mouth of the pipe. Looking up into the clear
blue sky, you see before you a dancing golden fiend, without visible
connection with the earth, swayed by the wind into fantastic shapes, and
whirling in every direction. As the gas from the well strikes the center
of the flame and passes partly through it, the lower part of the mass
curls inward, giving rise to the most beautiful effects gathered into
graceful folds at the bottom--a veritable pillar of fire. There is not a
particle of smoke from it. The gas from the wells at Washington was
allowed to escape through pipes which lay upon the ground. Looking down
from the roadside upon the first well we saw in the valley, there
appeared to be an immense circus-ring, the verdure having been burnt and
the earth baked by the flame. The ring was quite round, as the wind had
driven the flame in one direction after another, and the effect of the
great golden flame lying prone upon the earth, swaying and swirling with
the wind in every direction, was most startling. The great beast
Apollyon, minus the smoke, seemed to have come forth from his lair again.
The cost of piping is now estimated, at the present extremely low prices,
with right of way, at L1,600 sterling per mile, so that the cost of a
line to Pittsburg may be said to be about L27,000 sterling. The cost of
drilling is about L1,000, and the mode of procedure is as follows: A
derrick being first erected, a 6 inch wrought-iron pipe is driven down
through the soft earth till rock is reached from 75 to 100 feet. Large
drills, weighing from 3,000 to 4,000 lb., are now brought into use; these
rise and fall with a stroke of 4 to 5 feet. The fuel to run these drills
is conveyed by small pipes from adjoining wells. An 8-inch hole having
been bored to a depth of about 500 feet, a 5-5/8 inch wrought-iron pipe
is put down to shut off the water. The hole is then continued 6 inches in
diameter until gas is struck, when a 4-inch pipe is put down. From forty
to sixty days are consumed in sinking the well and striking gas. The
largest well known is estimated to yield about 30,000,000 cubic feet of
gas in twenty-four hours, but half of this may be considered as the
product of a good well. The pressure of gas as it issues from the mouth
of the well is nearly or quite 200 lb. per square inch. One of the gauges
which I examined showed a pressure of 187 lb. Even at works where we use
the gas nine miles from the well, the pressure is 75 lb. per square inch.
At one of the wells, where it was desirable to have a supply of pure
water, I found a small engine worked by the direct pressure of the gas as
it came from the well; and an excellent supply of water was thus obtained
from a spring in the valley. Eleven lines of pipe now convey gas from the
various wells to the manufacturing establishments in and around
Pittsburg. The largest of these for the latter part of the distance is 12
inches in diameter. Several are of 8 inches throughout. The lines
originally laid are 6 inches in diameter. Many of the mills have as yet
no appliances for using the gas, and much of it is still wasted. It is
estimated that the iron and steel mills of the city proper require fuel
equal to 166,000 bushels of coal per day; and though it is only two years
since gas was first used in Pittsburg, it has already displaced about
40,000 bushels of coal per day in these mills. Sixty odd glass works,
which required about 20,000 bushels of coal per day, mostly now use the
natural gas. In the work around Pittsburg beyond the city limits, the
amount of coal superseded by gas is about equal to that displaced in the
city. The estimated number of men whose labor will be dispensed with in
Pittsburg when gas is generally used is 5,000. It is only a question of a
few months when all the manufacturing carried on in the district will be
operated with the new fuel. As will be seen from the analyses appended to
this paper, it is a much purer fuel than coal; and this is a quality
which has proved of great advantage in the manufacture of steel, glass,
and several other products. With the exception of one, and perhaps two
concerns, no effort has been made to economize in the use of the new
fuel. In our Union Iron Mills we have attached to each puddling furnace a
small regenerative appliance, by the aid of which we save a large
percentage of fuel. The gas companies will no doubt soon require
manufacturers to adopt some such appliance. At present, owing to the
fact that there is a large surplus constantly going to waste, they allow
the gas to be used to any extent desired. Contracts are now made to
supply houses with gas for all purposes at a cost equal to that of the
coal bill for the preceding year. In the residences of several of our
partners no fuel other than this gas is now used, and everybody who has
applied it to domestic purposes is delighted with the change from the
smoky and dirty bituminous coal. Some, indeed, go so far as to say that
if the gas were three times as costly as the old fuel, they could not be
induced to go back to the latter. It is therefore quite within the region
of probability that the city, now so black that even Sheffield must be
considered clean in comparison, may be so revolutionized as to be the
cleanest manufacturing center in the world. A walk through our rolling
mills would surprise the members of the Institute. In the steel rail
mills for instance, where before would have been seen thirty stokers
stripped to the waist, firing boilers which require a supply of about 400
tons of coal in twenty-four hours--ninety firemen in all being employed,
each working eight hours--they would now find one man walking around the
boiler house, simply watching the water gauges, etc. Not a particle of
smoke would be seen. In the iron mills the puddlers have whitewashed the
coal bunkers belonging to their furnaces. I need not here say how much
pleasure it will afford me to arrange that any fellow members of the
Institute who may visit the republic are afforded an opportunity to see
for themselves this latest and most interesting development of the fuel
question. Good Mother Earth supplies us with all the fuel we can use and
more, and only asks us to lead it under our boilers and into our heating
and puddling furnaces, and apply the match. During the winter several
explosions have occurred in Pittsburg, owing to the escape of gas from
pipes improperly laid. The frost having penetrated the earth for several
feet and prevented escape upward, the freed gas found its way into the
cellars of houses, and, as it is odorless, its presence was not detected.
This resulted in several alarming explosions; but the danger is to be
remedied before next year. Lower pressure will be carried in the pipes
through the city, and escape pipes leading to the surface will be placed
along the surface at frequent intervals. In the case of manufacturing
establishments, the gas is led into the mills overhead, and, all the
pipes being in the open air, no danger of explosion is incurred.

The following extract from the report of a committee, made to the
American Society of Mechanical Engineers at a recent meeting, gives an
idea of the value of the new fuel: "Natural gas, next to hydrogen, is the
most powerful of the gaseous fuels, and, if properly applied, one of the
most economical, as very nearly its theoretical heating power can be
utilized in evaporating water. Being so free from all deleterious
elements, notably sulphur, it makes better iron, steel, and glass than
coal fuel. It makes steam more regularly, as there is no opening of
doors, and no blank spaces are left on the grate bars to let cold air in,
and, when properly arranged, regulates the steam pressure, leaving the
man in charge nothing to do but to look after the water, and even that
could be accomplished if one cared to trust to such a volatile
water-tender. Boilers will last longer, and there will be fewer
explosions from unequal expansion and contraction, due from cold draughts
of air being let in on hot plates.

"An experiment was made to ascertain the value of gas as a fuel in
comparison with coal in generating steam, using a retort or boiler of 42
inches diameter, 10 feet long, with 4 inch tubes. It was first fired with
selected Youghiogheny coal, broken to about 4 inch cubes, and the furnace
was charged in a manner to obtain the best results possible with the
stack that was attached to the boiler. Nine pounds of water evaporated to
the pound of coal consumed was the best result obtained. The water was
measured by two meters, one in the suction and the other in the
discharge. The water was fed into a heater at a temperature of from 60 deg.
to 62 deg.; the heater was placed in the flue leading from the boiler to the
stack in both gas and coal experiments. In making the calculations, the
standard 76 lb. bushel of the Pittsburg district was used. Six hundred
and eighty-four pounds of water were evaporated per bushel, which was
60.9 per cent. of the theoretical value of the coal. Where gas was burned
under the same boiler, but with a different furnace, and taking 1 lb. of
gas to be 2.35 cubic feet, the water evaporated was found to be 20.31
lb., or 83.4 per cent. of the theoretical heat units were utilized. The
steam was under the atmospheric pressure, there being a large enough
opening to prevent any back pressure, the combustion of both gas and coal
was not hurried. It was found that the lower row of tubes could be
plugged and the same amount of water could be evaporated with the coal;
but with gas, by closing all the tubes--on the end next the stack--except
enough to get rid of the products of combustion, when the pressure on the
walls of the furnace was three ounces, and the fire forced to its best,
it was found that very nearly the same results could be obtained. Hence
it was concluded that the most of the work was done on the shell of the

In no other way can I give the members of the Iron and Steel Institute so
much information in regard to this new fuel as by including in this paper
a very able communication from the chief chemist at our Edgar Thomson
Steel Works, Mr. S.A. Ford, who is to-day the highest authority upon the

"So much has been claimed for natural gas as regards the superiority of
its heating properties as compared with coal, that some analyses of this
gas, together with calculations showing the comparison between its
heating power and that of coal, may be of interest. These calculations
are, of course, theoretical in both cases, and it must not be imagined
that the total amount of heat, either in a ton of coal or 1,000 cubic
feet of natural gas, can ever be fully utilized. In making these
calculations I employed as a basis what in my estimation was a gas of an
average chemical composition, as I have found that gas from the same well
varies continually in its composition. Thus, samples of gas from the same
well, but taken on different days, vary in nitrogen from 23 per cent. to
_nil_, carbonic acid from 2 per cent. to _nil_, oxygen from 4 per cent,
to 0.4 per cent., and so with all the component gases. Before giving the
theoretical heating power of 1,000 cubic feet of this gas I will note a
few analyses. The first four are of gas from the same well; samples
taken on the same day that they were analyzed. The two last are from two
different wells in the East Liberty district:


| 1 | 2 | 3 | 4 | 5 | 6 |
When tested.........|10-28-84|10-29-84|11-24-84|12-4-84 |10-18-84|10-25-84|
| per ct.| per ct.| per ct.| per ct.| per ct.| per ct.|
Carbonic acid ......| 0.8 | 0.6 | Nil. | 0.4 | Nil. | 0.30|
Carbonic oxide......| 1.0 | 0.8 | .58 | 0.4 | 1.0 | 0.30|
Oxygen... ... ......| 1.1 | 0.8 | .78 | 0.8 | 2.10| 1.20|
Olefiant gas .......| 0.7 | 0.8 | 0.98| 0.6 | 0.80| 0.6 |
Ethylic hydride ....| 3.6 | 5.5 | 7.92| 12.30 | 5.20| 4.8 |
Marsh gas ..........| 72.18| 65.25| 60.70| 49.58 | 57.85| 75.16|
Hydrogen ...........| 20.02| 26.16| 29.03| 35.92 | 9.64| 14.45|
Nitrogen ...........| Nil. | Nil. | Nil. | Nil. | 23.41| 2.89|
Heat units .........|728,746 |698,852 |627,170 |745,813 |592,380 |745,591 |

"We will now show how the natural gas compares with coal, weight for
weight, or, in other words, how many cubic feet of natural gas contain as
many heat units as a given weight of coal, say a ton. In order to
accomplish this end we will be obliged, as I have said before, to assume
as a basis for our calculations what I consider a gas of an average
chemical composition, viz.:

Per cent.
Carbonic acid............................ 0.60
Carbonic oxide........................... 0.60
Oxygen................................... 0.80
Olefiant gas............................. 1.00
Ethylic hydride.......................... 5.00
Marsh gas............................... 67.00
Hydrogen................................ 22.00
Nitrogen................................. 3.00

"Now, by the specific gravity of these gases we find that 100 liters of
this gas will weigh 64.8585 grammes, thus:

Liters. grammes.

Marsh gas................. 67.0 48.0256
Olefiant gas.............. 1.0 1.2534
Ethylic hydride........... 5.0 6.7200
Hydrogen.................. 22.0 1.9712
Nitrogen.................. 3.0 3.7632
Carbonic acid............. 0.6 1.2257
Carbonic oxide............ 0.6 0.7526
Oxygen.................... 0.8 1.1468
Total................................... 64.8585

"Then, if we take the heat units of these gases, we will find:

Heat units
Grammes. contained.

Marsh gas................ 48.0256 627,358
Olefiant gas............. 1.2534 14,910
Ethylic hydride.......... 6.7200 77,679
Hydrogen................. 1.9712 67,929
Carbonic oxide........... 0.7526 1,808
Nitrogen................. 3.7630 -----
Carbonic acid............ 1.2257 -----
Oxygen................... 1.1468 -----
------- -------
Totals 64.8585 789,694

"64.8585 grammes are almost exactly 1,000 grains, and 1 cubic foot of
this gas will weigh 267.9 grains; then the 100 liters, or 64.8585
grammes, or 1,000 grains, are 3,761 cubic feet; 3,761 cubic feet of this
gas contains 789,694 heat units, and 1,000 cubic feet will contain
210,069,604 heat units. Now, 1,000 cubic feet of this gas will weigh
265,887 grains, or in round numbers 38 lb. avoirdupois. We find that
64.8585 grammes, or 1,000 grains, of carbon contain 523,046 heat units,
and 265,887 grains, or 38 lb., of carbon contain 139,398,896 heat units.
Then 57.25 lb. of carbon contain the same number of heat units as 1,000
cubic feet of the natural gas, viz., 210,069,604. Now, if we say that
coke contains in round numbers 90 per cent. carbon, then we will have
62.97 lb. of coke, equal in heat units to 1,000 cubic feet of natural
gas. Then, if a ton of coke, or 2,000 lb., cost 10s., 62.97 lb. will cost
4d., or 1,000 cubic feet of gas is worth 4d. for its heating power. We
will now compare the heating power of this gas with bituminous coal,
taking as a basis a coal slightly above the general average of the
Pittsburg coal, viz.:

Per cent.
Carbon................................... 82.75
Hydrogen................................. 5.31
Nitrogen................................. 1.04
Oxygen................................... 4.64
Ash...................................... 5.31
Sulphur.................................. 0.95

"We find that 38 lb. of this coal contains 146,903,820 heat units. The
64.4 lb. of this coal contains 210,069,640 heat units, or 54.4 lb. of
coal is equal in its heating power to 1,000 cubic feet of natural gas. If
our coal cost us 5s. per ton of 2,000 lb., then 54.4 lb. costs 1.632d.,
and 1,000 cubic feet of gas is worth for its heat units 1.632d. As the
price of coal increases or decreases, the value of the gas will naturally
vary in like proportions. Thus, with the price of coal at 10s. per ton
the gas will be worth 3.264d. per 1,000 cubic feet. If 54.4 lb. of coal
is equal to 1,000 cubic feet of gas, then one ton, or 2,000 lb., is equal
to 36,764 cubic feet, or 2,240 lb. of coal is equal to 40,768 cubic feet
of natural gas. If we compare this gas with anthracite coal, we find that
1,000 cubic feet of gas is equal to 58.4 lb. of this coal, and 2,000 lb.
of coal is equal to 34,246 cubic feet of natural gas. Then, if this coal
cost 26s. per ton, 1,000 cubic feet of natural gas is worth 91/2d. for its
heating power. In collecting samples of this gas I have noticed some very
interesting deposits from the wells. Thus, in one well the pipe was
nearly filled up with a soft grayish-white material, which proved on
testing to be chloride of calcium. In another well, soon after the gas
vein had been struck, crystals of carbonate of ammonia were thrown out,
and upon testing the gas I found a considerable amount of that alkali,
and with this well no chloride of calcium was observed until about two
months after the gas had been struck. In these calculations of the
heating power of gas and coal no account is of course taken of the loss
of heat by radiation, etc. My object has been to compare these two fuels
merely as regards their actual value in heat units."

Bearing in mind that it is never wise to prophesy unless you know, I
hesitate to speak of the future; but considering the experience we have
had in regard to the productiveness of the oil territory, which is now
yielding 70,000 barrels of petroleum per day, and which has continued to
increase year after year for twenty years, I see no reason to doubt the
opinion of experts that the territory which has already been proved to
yield gas will suffice for at least the present generation in and about

* * * * *



A very useful contrivance for the purpose of reporting automatically the
failure of the water supply to a gas-engine has been arranged by
Professor Ph. Carl, of Munich. What led to the adoption of the device was
that, during last winter, the water supply in the neighborhood of the
Professor's laboratory was several times cut off without previous notice;
the result being the failure of the water needed for cooling the cylinder
of his Otto gas-engine. On inquiring into the matter, he discovered that
the same thing frequently occurred in other places where gas-engines were
in use; and this caused him to design a contrivance to put an alarm-bell
into action at the instant when the water ceased to flow, and so enable
any overheating of the engine, and injuries thereby resulting, to be
prevented in time. The arrangement (represented half size in the
accompanying engraving) is screwed down directly to the water outflow
pipe, R. Before the aperture of the pipe is a lever, with a disk on one
arm, on to which the issuing water impinges, thereby keeping the lever in
the position indicated by the dotted lines. The effect of this is to
break the platinum contact at C, and so interrupt the circuit of an
alarm-bell placed in any suitable position. Suppose the water ceases to
flow; the spring, F, comes into play, contact is made at C, and the bell
continues to ring till some one comes to stop it. It is almost needless
to remark that the disk, D, and the pin, E, are composed of insulating
material, such as vulcanite.--_Jour. Gas Lighting._

* * * * *



It frequently happens in the laboratory that platinum vessels, after
long-continued use, begin to show signs of wear, and become perforated
with minute pinholes. When they have reached this stage, they are usually
accounted of no further utility, and are disposed of as scrap; not that
it is impossible to repair them--for with fine gold wire and an
oxyhydrogen jet this is easily feasible--but that the proper appliances
and skill are not in possession of all. Irrespective of the manipulation
of the hydrogen jet, it is rather difficult without long practice to hold
the end of the fine wire precisely over the aperture and to keep it in
position. It occurred to me that, if the gold in a finely divided
condition could be placed in very intimate contact with the platinum,
judging from the fusibility of gold-platinum alloys, union could be
effected at a lower temperature over the ordinary gas blowpipe. I tried
the experiment, and found the supposition correct. The substance I used
was auric chloride, AuCl_{3}, which, as is well known, splits up on
heating, first into aurous chloride, and at a higher temperature gives
off all its chlorine and leaves metallic gold. Operating on a perforated
platinum basin, in the first instance, I placed a few milligrammes of the
aurous chloride from a 15 grain tube precisely over the perforation, and
then gently heated to about 200 deg. C. till the salt melted and ran through
the holes. A little further heating caused the reduced gold to solidify
on each side of the basin. The blowpipe was now brought to bear on the
bottom of the dish, right over the particular spots it was wished to
solder, and in a few moments, at a yellow-red heat (in daylight), the
gold was seen to "run." On the vessel being immediately withdrawn, a very
neat soldering was evident. The operation was repeated several times,
till in a few minutes the dish had been rendered quite tight and

Using the gold salt in this way, the principal difficulty experienced in
holding gold wire unflinchingly in the exact position vanishes, while
only a comparatively low temperature and small amount of gold is
necessary. Care must be taken to withdraw the platinum from the flame
just at the moment the gold is seen to run, for if the heat be continued
longer, the gold alloys with a larger surface of platinum, spreads, and
leaves the aperture empty. As in the case of all gold-soldered vessels,
the article cannot afterward be safely exposed to a temperature higher
than that at which the soldering was effected, and on this account it is
advisable to use as small an amount of auric chloride as possible. When
the perforations are of comparatively large size, the repairing is not so
easy, owing to the auric chloride, on fusing, refusing to fill them. I
find, however, that if some spongy platinum be mixed with a few
milligrammes of the gold salt, pressed into the perforation, and heat
applied as directed, a very good soldering can be effected. It is well to
hammer the surface of the platinum while hot, so as to secure perfect
union and welding of the two surfaces. This may be done in a few minutes
in such a manner as to render the repair indistinguishable. Strips of
platinum may be joined together in much the same way as already
described--a few crystals of auric chloride placed on each clean surface
and gently heated till nearly black, then bound together and further
heated for a few moments in the blowpipe flame. Rings and tubes can also
be formed on a mandrel, and soldered in the same fashion, and the chemist
thus enabled to build up small pieces of apparatus from sheet platinum in
the laboratory.--_Chem. News._

* * * * *


The sides of solid bodies, whatever be the degree of hardness, and
however fine the texture, possess surfaces formed of a succession of
projections and depressions. When two bodies are in contact, these
projections and indentations fit into one another, and the adherence that
results is proportional to the degree of roughness of the surfaces. If,
by a more or less energetic mechanical action, we move one of the bodies
with respect to the other, we shall produce, according as the action
overcomes cohesion, more or less disintegration of the bodies. The
resulting wear in each of them will evidently be inversely proportional
to its hardness and the nature of its surface; and it will vary, besides,
with the pressure exerted between the surfaces and the velocity of the
mechanical action. We may say, then, that the wear resulting from rubbing
two bodies against each other is a function of their degree of hardness,
of the extent and state of their surface, of the pressure, of the
velocity, and of the time.

[Illustration: FIGS. 1, 2 and 3.--APPARATUS FOR SAWING STONE.]

According as these factors are varied in a sense favorable or unfavorable
to their proper action, we obtain variations in the final erosion. Thus,
in rubbing together two bodies of different hardness and nature of
surface, we obtain a wear inversely proportional to the hardness and
state of polish of their surfaces. Through the interposition of a
pulverized hard body we can still further accelerate such wear, as a
consequence of the rapid renewal of the disintegrating element.

The gradual wear effected over the entire surface of a body brings about
a polish, while that effected along a line or at some one point
determines a cleavage or an aperture.

The process usually employed in quarries or stone-yards for sawing
consists in slowly moving a stone-saw backward and forward, either by
hand or machinery, and with scarcely any pressure. Mr. P. Gray has,
however, devised a new process, which is based upon the theoretical
considerations given above. His _helicoidal saw_ is, in reality, an
endless cable formed by twisting together three steel wires in such a way
as to give the spirals quite an elongated pitch.

The apparatus in its form for cutting blocks of stone into large slabs
(Figs. 1, 2, and 3) consists of two frames, A A, five feet apart, each
formed of two iron columns, 71/2 feet in height and one foot apart, fixed
to cast iron bases resting upon masonry. At the upper part, a frame, B B,
formed of double T-irons cross-braced here and there, supports a
transmission composed of gearwheels, R R, and a pitch-chain, G G. Along
the columns of the frame, which serve as guides, move two kinds of
pulley-carriers, C C. The pulleys, D D, are channeled, and receive the
cable, a a, which serves as a helicoidal saw. The direction of the saw's
motion is indicated by the arrow. The carriages, C C, are traversed by
screws, V V, which are fixed between the columns. The extremity, v, of
the axle of the pulley to the right is threaded, and actuates a
helicoidal wheel, E, which transmits motion to the wheel, R, through the
intermedium of the vertical shaft, F. This transmission, completed by the
wheels, R R, and the pitch-chains, G G, is designed to move the saw
vertically, through the simultaneous shifting of the carriages, C C. A
tension weight, P, through the intermedium of pulleys, D_{1} D_{1},
permits of keeping the saw taut. A reservoir, H, at the upper part of the
frame, B B, contains the water and sand necessary for sawing. The feeding
is effected by means of a rubber tube, I, terminating in a flattened
rose, J, which is situated over the aperture made by the saw. A small
pump, L. over the reservoir takes water from K, and raises it to H. The
sand is put in by hand.

Above the basin, K, a system of rails and ties supports the carriage, Q,
upon which is placed the block of stone to be sawn. When one operation
has been finished, and it is desired to begin another, it is necessary to
raise the pulley-carriers and the saw. In order to do this quickly, there
is provided a special transmission, M, which is actuated by hand, through
a winch.

The work done by this saw is effected more rapidly than by the ordinary
processes, and certain very hard rocks, usually regarded as almost
intractable, can be sawed at the rate of from one to one and a half
inches per hour.


For sawing marble into slabs of all thicknesses, the arrangement
described above may be replaced by a system consisting of two drums
having several channels to receive as many saws, or two corresponding
series of channeled pulleys, b b (Fig. 4), independent of each other, but
keyed to the same axles, i i. When the pulleys have been properly spaced
by means of keys, the whole affair is rendered solid by a bolt, g. The
extremity of the axles forms a nut into which pass vertical screws, c c.
These latter are connected above with cone-wheels, l l, which, gearing
with bevel wheels keyed to the shafts, e, secure a complete
interdependence of the whole. The ascending motion, which is controlled
by the endless screws, f, and the helicoidal wheels, m, is in this way
effected with great regularity. Uprights, a a, of double T-iron, fixed to
joists, k k, and connected and braced by pieces, d d, form a strong


The power necessary to run this kind of saw is less than _n_ x 1/4 H.P.,
on account of the number of passive parts. The most interesting
application of the helicoidal saw is in the exploitation of quarries.
Fig. 5 represents a Belgian marble quarry which is being worked by Mr.
Gay's method.

_Tubular Perforators_.--Mr. Gay has rendered his saw completer by the
invention of a tubular perforator for drilling the preliminary well. It
is based upon the same principle as the Leschot rotary drill, but differs
from that in its extremity being simply of tempered steel instead of
being set with black diamonds. A special product, called metallic
agglomerate, is used instead of sand for hastening the work.

[Illustration: FIG. 6.--TUBULAR PERFORATOR.]

The apparatus, Fig. 6, consists of an iron plate cylinder, A, 271/2
inches in diameter, and of variable length, according to the depth to be
obtained, and terminating beneath in a steel head, B, of greater
thickness. This cylinder is traversed by a shaft, C, to which it is
keyed, and which passes through the center of the aperture drilled. This
shaft is connected with the cylinder, A, through the intermedium of cross
bars, D, and transmits thereto a rapid rotary motion, which is received
at the upper part from a telodynamic wire that passes through the channel
of the horizontal pulley, P. This latter is supported by a frame
consisting of three uprights, Q Q, strengthened by stays, R R, fixed to
the ground.

In order that the cylinder, A, may be given a vertical motion, cords, M
M, fixed to a piece, S, loose on the hub, D, wind round the drum of a
windlass, T, after passing over the pulleys, p p.

The rapid gyratory motion of the cylinder, along with the erosive action
of the metallic agglomerate, rapidly wears away the rock, and causes the
descent of the perforator. During this operation a core of marble forms
in the cylinder. This is detached by lateral pressure, and is capable of
being utilized. The tool descends at the rate of from 20 to 24 inches per
hour, or from 8 to 10 yards per day in ordinary lime rock.--_Le Genie

* * * * *



The Aqueous Works and Diamond Rock-boring Company, Limited, of London,
show at the Inventions Exhibition, London, a light portable rock-boring
machine for prospecting for minerals, water, etc. It is capable of
sinking holes from 2 in. to 5 in. in diameter, and to a depth of 400 ft.
The screwed boring spindle, which is in front of the machine, is actuated
by miter gearing driven by a six horse power engine; the speed of driving
is 400 revolutions a minute. The pump shown on the left-hand side of the
engraving is used to deliver a constant stream of water through the
boring bar, the connection being made by a flexible hose. Suitable
winding gear for raising or lowering the lining tubes, boring rods, etc.,
is also mounted on the same frame. The drill is automatic in its action,
and the speed can be regulated by friction gearing. The front part of the
carriage is arranged so that it can be swung clear of the drill to raise
and lower the bore rods, etc.

* * * * *


Among the safety appliances which are to be found in the Mining Section
of the Inventions Exhibition is a model of an ingenious contrivance for
the prevention of overwinding, the joint patent of Mr. W.T. Lewis,
Aberdare, lead mineral agent to the Marquis of Bute, and W.H. Massey,
electric light engineer to the Queen. Both these gentlemen, having been
members of jury, were not allowed to compete for an award. The invention,
says _Engineering_, seems to possess considerable merit, and it should
prove of practical utility in collieries where enginemen are usually kept
winding for many hours at a stretch, and where the slightest mistake on
the part of the driver may lead to an accident.

Safety hooks are often fitted to winding ropes, and although the damage
to life and property is greatly reduced by the use of them, they do not
protect a descending cage from injury in a case of overwinding; besides
which, they are almost useless when a wild run takes place, an accident
which, strange to say, has already occurred many times after engines and
boilers have been laid off for repairs. Stop valves are left open, the
reversing lever is not fixed in mid-gear, steam is got up in the boilers
at a time when no one is in the engine house, and the engines run away.


Various devices have been suggested and tried as a preventive, but their
application has either caused as much mischief as a bad accident, or it
has depended upon the driver doing something intentionally; whereas in
the automatic gear of Messrs. Massey and Lewis, of which an illustration
is annexed, there is nothing to cause damage or to interfere in any way
with the proper handling of the engines, and it is practically out of the
power of the driver to render the gear inoperative. It is here shown in
its simplest form as applied to the ordinary reversing and steam handles
of a winding engine, the only additions being an arm jointed to the top
of the valve spindle, with its connections to the shaft of the reversing
lever, and a disk receiving a suitable motion from the main shaft of the
engine. On the disk is a projecting piece or stop which is brought into
such positions, at or near the end of each journey, that the stop valve
cannot be opened, except slightly, when the reversing lever is not set
for winding in the proper direction, or when the cages have reached a
point beyond which it is undesirable that the engine driver should have
the power of turning on full steam. Thus, if one cage is at bank, the
driver cannot draw it up into the head gear suddenly; but after it has
been lifted slowly off the keeps or fangs, and the reversing lever thrown
over, the stop valve can be lifted wide open; and supposing that while
the engine is running the driver neglects to shut off steam in proper
time, then the projecting piece on the disk in traveling round, slowly
or quickly, and by steps according to requirements, will come in contact
with the driver, and so prevent an accident by bringing the reversing
lever into or beyond mid-gear.

Messrs. Lewis and Massey contemplate the use of governors in combination
with various forms of their automatic gear, so as to provide for every
imaginable case of winding, and also to avoid accidents when heavy loads
are sent down a pit; the special feature in their mechanism being that
when two or more things happen with regard to the positions of steam or
reversing handles, speed or position of cages in the pit, whatever it may
be necessary to do to meet the particular case shall be done

* * * * *


[Footnote: An address by Prof. W.H. Corfield, M.D., M.A., delivered
before the Sanitary Institute of Great Britain, July 9, 1885.--_Building

As the supply of water to large populations is one of the most important
subjects in connection with sanitary matters, and one upon which the
health of the populations to a very large extent depends, I propose to
give a short account of some of the more important works carried out for
this purpose by the ancient Romans--the great sanitary engineers of
antiquity--more especially as I have had exceptional opportunities of
examining many of those great works in Italy, in France, and along the
north coast of Africa. Of the aqueducts constructed for the supply of
Rome itself we have an excellent detailed account in the work of
Frontinus, who was the controller of the aqueducts under the emperor
Nerva, and who wrote his admirable work on them about A.D. 97.

It may be interesting in passing to mention that Frontinus was a
patrician, who had commanded with distinction in Britain under the
emperor Vespasian, before he was appointed by the emperor Nerva as
controller (or, we should say, surveyor) of the aqueducts. He was also an
antiquarian, and in his work he not only describes the aqueducts as they
were in this time, but also gives a very interesting history of them. He
begins by telling us that for 441 years after the building of the
city--that is to say, B.C. 312--there was no systematic supply of water
to the city; that the water was got direct from the Tiber, from shallow
wells, and from natural springs; but that these sources were found no
longer to be sufficient, and the construction of the first aqueduct was
undertaken during the consulship of Appius Claudius Crassus, from whom it
took the name of the Appian aqueduct. This was, as may be expected from
its being the first aqueduct, not a very long one; the source was about
eight miles to the east of Rome, and the length of the aqueduct itself
rather more than eleven miles, according to Mr. James Parker, to whose
paper on the "Water Supply of Ancient Rome" I am indebted for many of the
facts concerning the aqueducts of Rome itself. This aqueduct was carried
underground throughout its whole length, winding round the heads of the
valleys in its course, and not crossing them, supported on arches, after
the manner of more recent constructions; it was thus invisible until it
got inside the city itself, a very important matter when we consider how
liable Rome was, in these early times, to hostile attacks.

It was soon found that more water was required than was brought by this
aqueduct, and it was no doubt considered desirable to have tanks at a
higher level in the city than those supplied by the Appian aqueduct. It
was determined, therefore, to bring water from a greater height, and from
a greater distance, and the river Anio, above the falls at Tivoli, was
selected for this purpose. The second aqueduct, the Anio Vetus, was no
less than 42 miles in length, and was, like the Appian, entirely under
the surface of the ground, except at its entrance into Rome at a point
about 60 ft. higher than the level of the Appian aqueduct.

Little search has been made for the remains of this aqueduct, and its
exact course is not known; but during my examination of the remains of
the subsequent aqueducts at a place called the Porta Furba, near Rome,
where the ruins of five aqueducts are seen together, and at, or close to,
which point the Anio Vetus must also have passed underground, I was
rewarded for my search by discovering a hole, something like a fox's
hole, leading into the ground; and on clearing away a few loose stones
which had apparently been thrown into it, and putting my arm in, I found
that it led into the specus or channel of an underground aqueduct; and on
relating this incident to the late Mr. John Henry Parker, the
antiquarian, who was then in Rome, and showing him a sketch of the place,
he said that he had no doubt that I had been fortunate enough to discover
the exact position of the veritable Anio Vetus at that spot. These two
aqueducts sufficed for the supply of Rome with water for about 120 years,
for Frontinus tells us that 127 years after the date at which the
construction of the Anio Vetus was undertaken--that is to say, the 608th
year after the foundation of the city--the increase of the city
necessitated a more ample supply of water, and it was determined to bring
it from a still greater distance. It was no longer considered necessary
to conceal the aqueduct underground during the whole of its course, and
so it was in part carried above ground on embankments or supported upon
arches of masonry. The water was brought from some pools in one of the
valleys on the eastern side of the Anio, some miles farther up than the
point from which the Anio Vetus was supplied; and the new aqueduct, which
was 54 miles in length, was called the Marcian, after the Praetor Marcius,
to whom the work was intrusted. Frontinus also tells us the history of
the other six aqueducts which were in existence in his time, viz., the
Tepulan, the Julian, the Virgo, the Alsietine or Augustan, the Claudian,
and the Anio Novus; the last two being commenced by the Emperor Caligula,
and finished by Claudius, because "seven aqueducts seemed scarcely
sufficient for public purposes and private amusements;" but it is not
necessary for our purpose to give any detailed account of the course of
these aqueducts; it is only necessary to mention one or two very
interesting points in connection with them. In order to allow of the
deposit of suspended matters, piscinae, or settling reservoirs, were
constructed in a very ingenious manner. Each had four compartments, two
upper and two lower; the water was conducted into one of the upper
compartments, and from this passed, probably by what we should call a
standing waste or overflow pipe, into the one below; from this it passed
(probably through a grating) into the third compartment at the same
level, and thence rose through a hole in the roof of this compartment
into the fourth, which was above it, and in which the water, of course,
attained the same level as in the first compartment, thence passing on
along the aqueduct, having deposited a good deal of its suspended matter
in the two lower compartments of the piscinae. Arrangements were made by
which these two lower compartments should be cleaned out from time to
time. The specus or channel itself was, of course, constructed of
masonry, generally of blocks of stone cemented together, and it was
frequently, though not, it would appear always, lined with cement inside.
It was roofed over, and ventilating shafts were constructed at intervals;
in order to encourage the aeration of the water, irregularities were
occasionally introduced in the bed of the channel. The water supplied by
the different aqueducts was of various qualities; thus, for instance,
that of the Alsietine, which was taken from a lake about 18 miles from
Rome, was of an inferior quality, and was chiefly used to supply a large
naumachia, or reservoir, in which imitation sea fights were performed;
while, on the other hand, the water of the Marcian was very clear and
good, and was therefore used for domestic purposes. Frontinus gives the
most accurate details as to the measurements of the amount of water
supplied by the various aqueducts, and the quantities used for different
purposes. From these details Mr. Parker computes the sectional area of
the water at about 120 square feet, and says: "We can form some opinion
of the vast quantity if we picture to ourselves a stream 20 ft. wide by 6
ft. deep constantly pouring into Rome at a fall six times as rapid as
that of the river Thames." He considers that the amount was equivalent to
about 332 million gallons a day, or 332 gallons per head per day,
assuming the population of the city to be a million. When we consider
that we in London have only 30 gallons a head daily, and that many other
towns have less, we get some idea of the profusion with which water was
supplied to ancient Rome. But the remains of Roman aqueducts are not only
to be found near Rome. Almost every Roman city, whether in Italy or in
the south of France, or along the north coast of Africa, can show the
remains of its aqueduct, and almost the only things that are to be seen
on the site of Carthage are the remains of the Roman water tanks and the
ruins of the aqueduct which supplied them. The most beautiful aqueduct
bridge in the world, on the course of the aqueduct which supplied the
ancient Nemaucus, now Nismes, still stands, and is called, from the name
of the department in which it is, the Pont du Gard. It consists of a row
of large arches crossing the valley over which the water had to be
carried, surmounted by a series of smaller arches, and these again by a
series of still smaller ones, carrying the specus of the aqueduct. This
splendid bridge still stands perfect, so that one can walk through the
channel along which the water flowed, and it might be again used for its
original purpose. There was, however, one city which, from the fact that
a great part of it was situated upon a hill, was more difficult to supply
with water than any of the rest, and which, at the same time, from its
size, its great importance, and the fact that it was the favorite summer
residence of several of the Roman emperors, and notably of Claudius, who
was born there, and who had a palace on the top of the hill, must of
necessity be supplied with plenty of water, and that too from a
considerable height. I refer to Ludgunum (now Lyons), then the capital of
Southern Gaul. This city was built by Lucius Munatius Plaucus, by order
of the Senate in A.U.C. 711. Augustus went there in A.U.C. 738, and
afterward lived there from 741 to 744. It was he who raised it to a very
high rank among Roman cities. It had its forum near the top of the hill
now called Fourvieres (probably a corruption of Forum Vetus), an imperial
place on the summit of the same hill, public baths, an amphitheater, a
circus, and temples.

In order to supply this city with water, standing as it did on the side
of a hill at the junction of two great rivers (now Rhone and Saone), it
was necessary to search for a source at a sufficient height, and this
Plaucus found in the hills of Mont d'Or, near Lyons, where a plentiful
supply of water was found at a sufficient height, viz., that of nearly
2,000 ft. above the sea. From this point an aqueduct, sometimes called
from its source the aqueduct of Mont d'Or, and sometimes the aqueduct of
Ecully, from the name of a large plain which it crossed, was constructed,
or rather two subterranean aqueducts were made and joined together into
one, which crossed the plain of Ecully, in a straight line still
underground; but the ground around Lyons was not like the Campagna, near
Rome, and it was necessary to cross the broad and deep valley now called
La Grange, Blanche. This, however, did not daunt the Roman engineers;
making the aqueduct end in a reservoir on one side of the valley, they
carried the water down into the valley, probably by means of lead pipes,
in the manner which will be described more at length further on, across
the stream at the bottom of the valley by means of an aqueduct bridge 650
ft. long, 75 ft. high, and 281/2 ft. broad, and up the other side into
another reservoir, from which the aqueduct was continued along the top of
a long series of arches to the reservoir in the city, after a course of
about ten miles.

In the time of Augustus, however, it was found that the water brought by
this aqueduct was not sufficient, especially in summer; and as there was
a large Roman camp which also required to be supplied with water,
situated at a short distance from the city, it was determined to
construct a second aqueduct. For this purpose the springs at the head of
a small river, called now the Brevenne, were tapped, and conveyed by
means of an underground aqueduct (known as the aqueduct of the Brevenne)
which wound round the heads of the valleys, and after a course of about
thirty miles is believed by some to have arrived at the city, but by
others to have stopped at the Roman camp, and to have been constructed
exclusively for its supply.

I have here a diagram, after Flacheron, showing a section of this
aqueduct, and this will give a very good general idea of the section of a
Roman aqueduct where constructed underground. It will be seen that the
specus or channel is 60 centimeters (or nearly 2 ft.) wide, and 1m. 57c.
(or a little over 5 ft.) high, and that it is lined with a layer of 3 c.
(or nearly 11/4 in.) of cement. It is constructed of quadrangular blocks of
stone cemented together, and has an arched stone roof. It will be noticed
also that the angles at the lower part of the channel are filled up with
cement; it appears also that this aqueduct crossed a small valley by
means of inverted siphons. But neither of these aqueducts came from a
source sufficiently high to supply the imperial palace on the top of

Their sources are, in fact, according to Flacheron, at a height of nearly
50 ft. below the summit of Fourvieres, and it was, therefore, considered
necessary by the emperor Claudius to construct a third aqueduct. The
sources of the stream now called the Gier, at the foot of Mont Pila,
about a mile and a half above St. Chamond, were chosen for this purpose,
and from this point to the summit of Fourvieres was constructed by far
the most remarkable aqueduct of ancient times, an engineering work which,
as will be seen from the following description, partly taken from
Montfalcon's history of Lyons, partly from Flacheron's account of this
aqueduct, and partly from my own observations on the spot, reflects the
greatest possible credit on the Roman engineers, and shows that they were
not, as has been frequently supposed by those who have only examined
aqueducts at Rome, by any means ignorant of the elementary principles of

To tap the sources of a river at a point over 50 miles from the city, and
to bring the water across a most irregular country, crossing ten or
twelve valleys, one being over 300 ft. deep, and about two-thirds of a
mile in width, was no easy task; but that it was performed the remains of
the aqueduct at various parts of its course show clearly enough. It
commences, as I have said, about a mile and a half from the present St.
Chamond, a town on the river Gier, about 16 miles from St. Etienne. Here
a dam appears to have been constructed across the bed of the river,
forming a lake from which the water entered the channel of the aqueduct,
which passed along underground until it came to a small stream which it
crossed by a bridge, long since destroyed.

After this it again became subterraneous for a time, and then crossed
another stream on a bridge of nine arches, the ruins of some of the
columns of which are still to be seen; and from these ruins it would
appear that the bridge had, at some time or another, been destroyed,
probably by the stream running under it having become torrential, and
subsequently rebuilt; again it became concealed underground, to reappear
in crossing a small valley and another small stream, when it was again
concealed by the ground, and in one or two places channels were even cut
for it through the solid rock, after which it reappeared on the surface
at a point where now stands the village of Terre-Noire, and where it was
necessary that it should somehow or another cross a broad and deep
valley. It ended in a stone reservoir, from which eight lead pipes
descending into the valley were carried across the stream at the bottom
on an aqueduct bridge, about 25 ft. wide, and supported by twelve or
thirteen arches, and then mounted the other side of the valley into
another reservoir, of which scarcely any remains are now seen, from which
the aqueduct started again, disappearing almost immediately under the
surface of the ground, to appear again from time to time crossing similar
valleys and streams upon bridges, the remains of some of which may still
be seen, until it reached Soucieu, on the edge of the valley of the
Garonne, where are still seen the remains of a splendid bridge, the
thirteenth on its course, nearly 1,600 ft. long, and attaining a height
of 56 ft. at its highest point above the ground. The object of this
bridge was to convey the channel of the aqueduct at a sufficient height
into a reservoir on the edge of the valley.

The remains of this bridge leave no doubt that it was purposely destroyed
by barbarians; some of the arches near the end of it remain, while the
rest have been thrown down, some on one side and some on the other; but
happily the arches next to the reservoir, at the end of the bridge and on
the edge of the valley, remain, and the reservoir itself is still in part
intact, supported on a huge mass of masonry. Four holes are to be seen in
that part of the front of the reservoir which is left, being the holes
from which the lead pipes descended into the valley. There must have been
nine of these pipes in all. These holes are elliptical in shape, being 12
in. high by 91/2 in. wide, and the interior of the reservoir is still seen
to be covered with cement. The walls of the reservoir were about 2 ft. 7
in. thick, and were strengthened by ties of iron; it had an arched stone
roof in which there was an opening for access. From this the nine lead
pipes descended the side of the valley supported on a construction of
masonry, crossed the river by an aqueduct bridge, and ascended into
another reservoir on the other side, entering the reservoir at its upper
part just below the spring of the arches of the roof. From this reservoir
the aqueduct passed to the next on the edge of the large and deep valley
of Bonnan, being underground twice and having three bridges on its
course, the last of which, the sixteenth on the course of the aqueduct,
ends in a reservoir on the edge of the valley. Only one of the openings
by which the siphons, of which there were probably ten, started from the
reservoir is now left. The bridge across the valley below had thirty
arches, and was about 880 ft. long by 24 ft. wide.

A number of the arches still remain standing, and, the pillars of the
arches were constructed of transverse arches themselves. The work
consisted of concrete, formed with Roman cement so hard that it turns the
points of pickaxes when employed against it, with layers of tiles at
regular intervals. The surface of the concrete is covered with small
cubical blocks of stone placed so that their diagonals are horizontal and
vertical, and forming what is known as _opus reticulatum_. After crossing
the bridge the pipes were carried up the other side of the valley into a
reservoir, of which little remains, and then the aqueduct was continued
to the next valley, passing over three bridges in its course. This
valley, that of St. Irenee, is much smaller than either of the others,
but nevertheless it was deep enough to necessitate the construction of
inverted siphons, of which there were eight. Leaving the reservoir on the
other side of this valley, the aqueduct was carried on a long bridge (the
twentieth on its course) which crossed the plateau on the top of
Fourvieres and opened into a large reservoir, the remains of which are
still to be seen on the top of that hill.

From this reservoir, which was 77 ft. long and 51 ft. wide, pipes of lead
conveyed the water to the imperial palace and to the other buildings near
the top of the hill. Some of these lead pipes were found in a vineyard
near the top of Fourvieres at the beginning of the eighteenth century,
and were described by Colonia in his history of Lyons. They are made of
thick sheet lead rolled round so as to form a tube, with the edges of the
sheet turned upward, and applied to one another in such a way as to leave
a small space, which was probably filled with some kind of cement. These
pipes, of which it is said that twenty or thirty, each from 15 ft. to 20
ft. long, were found, were marked with the initial letters TI. CL. CAES.
(Tiberius Claudius Caesar), and afford positive evidence that the work was
carried out under the emperor Claudius. Lead pipes, constructed in a
similar manner, have also been found at Bath, in this country, in
connection with the Roman baths. The great difference between this
aqueduct and those near Rome arises from the fact that, instead of being
carried across a nearly flat country, it was carried across one
intersected with deep ravines, and that it was therefore necessary to
have recourse to the system of inverted siphons. There can be no doubt
that the inverted siphons were made of lead, although no remains of them
have been found; for we know that the Romans used lead largely, and, as
we have seen, pieces of the lead distribution pipes have been found. It
is possible, and even likely, that strong cords of hemp were wound round
the pipes forming the siphons, as is related by Delorme in describing a
similar Roman aqueduct siphon near Constantinople; Delorme also
describes, in the aqueduct last mentioned, a pipe for the escape of air
from the lowest part of the siphon carried up against a tower, which was
higher than the aqueduct, and it is certain that there must have been
some such contrivance on the siphons of the aqueduct constructed at

Flacheron supposes that they consisted of small pipes carried from the
lowest part of the siphons up along the side of the valley and above the
reservoirs, or, in some instances, of taps fixed at the lowest part of
the siphons. The Romans have been blamed for not using inverted siphons
in the aqueducts at Rome, and it has been said that this is a sufficient
proof that they did not understand the simplest principles of hydraulics,
but the remains of the aqueducts at Lyons negative this assumption
altogether. The Romans were not so foolish as to construct underground
siphons, many miles long, for the supply of Rome; but where it was
necessary to construct them for the purpose of crossing deep valleys,
they did so. The same emperor Claudius who built the aqueduct at Rome
known by his name built the aqueduct of Mont Pila, at Lyons, and it is
quite clear, therefore, that his engineers were practically well
acquainted with the principles of hydraulics. It is thus seen that the
ancient Romans spared no pains to obtain a supply of pure water for their
cities, and I think it is high time that we followed their example, and
went to the trouble and expense of obtaining drinking water from
unimpeachable sources, instead of, as is too often the case, taking
water which we know perfectly well has been polluted, and then attempting
to purify it for domestic purposes.

* * * * *


By Chief Engineer JOHN LOWE, U.S. Navy.

The purpose of this article is to point out an easy method whereby any
intelligent engineer can determine the point at which it is most
economical to cut off the admission of steam into his cylinder.

In the attack upon such a problem, it is useful to employ all the senses
which can be brought to bear upon it; for this purpose, diagrams will be
used, in order that the sense of sight may assist the brain in forming
its conclusions.


Fig. XABCX is an ideal indicator card, taken from a cylinder, imagined to
be 600 feet long, in which the piston, making one stroke per minute, has
therefore a piston speed of 600 feet per minute. Divide this card into
any convenient number of ordinates, distant _dx_ feet from each other,
writing upon each the absolute pressure measured upon it from the zero
line XX.

By way of example, let the diameter of the cylinder be 29.59 inches, and
let the back pressure from all causes be 7 pounds uniformly throughout.
It will be represented by the line b_{1}, b_{2}, etc. This quantity
subtracted from the pressures p_{1}, p_{2}, etc., leaves the remainder
(p-b) upon each ordinate, which remainder represents the net pressures
which at that point may be applied to produce external power.

If, now, A is the area of the piston, then the external power (d W)
produced between each ordinate is:

To any convenient scale, upon each ordinate, set off the appropriate
power as calculated by this equation (1).

dW = --------------. (1.)

There will result the curve _w, w, w_, determining the power which at any
point in the diagram is to be regarded as a gain, to be carried to the
credit side of the account.

It is evident that, so long as the gains from expansion exceed the losses
from expansion, it is profitable to proceed with expansion, but that
expansion should cease at that point at which gains and losses just
balance each other.


The requisite data are furnished by the experiments conducted some years
since by President D.M. Greene, of Troy College, for the Bureau of Steam
Engineering, U.S. Navy.

According to these experiments, the heat which is lost per hour by
radiation through a metallic plate of ordinary thickness, exposed to dry
air upon one side and to the source of heat upon the other, for one
degree difference in temperature, is as follows:

Condition. Heat units.

Naked...................................... 2.9330672
Covered with hair felt, 0.25 inch thick.... 1.0540710
" " 0.50 " .... 0.5728647
" " 0.75 " .... 0.4124625
" " 1.00 " .... 0.3070554
" " 1.25 " .... 0.2746387
" " 1.50 " .... 0.2507097

If now t' = temperature of steam at the ordinate,
t = temperature of the surrounding atmosphere,
dS = surface of the cylinder included between each ordinate,
k = that figure from the table satisfying the conditions,
then the power loss (dR) per minute will be:

k (t'-t)dS
dR = ( -- ) ----------. (2)
60 33,000

To the same scale as the power gains, upon each ordinate, set off the
appropriate power loss, as calculated by this equation (2).

There will result the curve r, r, r, which determines the power which at
any point in the diagram is to be regarded as a loss, to be carried to
the debit side of the account. This curve of losses intersects the curve
of gains at a point (it is evident) where each equals the other.

Therefore this is the point at which expansion should cease, and this
absolute pressure is the economic terminal pressure, which determines the
number of expansions profitable under the given conditions.

In the foregoing example are taken k = 0.3070554, t' = 331.169, t = 60,
while the back pressure was taken at 7 pounds.

By way of further illustration, first let the back pressure be changed
from 7 to 5.

By equation 1 there will result a new curve of gains, W, W, W, a portion
only being plotted.

Second, let t' = 331.169 as before.
t = 150 instead of 60.
k = 0.2507097 instead of 0.3070554.

There will result the second curve of losses, R, R, R, intersecting the
second curve of gains at the point F, the new economic point for our new

These two examples fully illustrate the whole subject, furnishing an easy
and, when carefully made, a very exact calculation and result.

The following are a few of the general conclusions to be drawn:

1. That radiation is a tangible and measurable cause, sufficient to
account for all losses heretofore ascribed to an intangible,
immeasurable, and wholly imaginary cause, viz., "internal evaporation and

2. In order to prevent the high initial temperatures now used becoming a
source of loss, it is necessary to prevent the quantity dS (t'-t)
becoming great, by making dS as small as possible. In other words, we
must compound our engines. Thus for the first time is pointed out the
true reason why compound engines are economical heat engines.

3. The foregoing reasoning being correct, it follows that steam jackets
are a delusion.

4. In order to attain economy, we must have high initial temperatures,
small high pressure cylinders, low back pressures from whatsoever cause,
high piston speeds, short rather than long strokes, to avoid the cooling
effects of a long piston rod; but especially must we have scrupulous and
perfect protection from radiation, especially about the cylinder heads,
now oftentimes left bare.

* * * * *


[Footnote: From a recent lecture before the Franklin Institute,

By Lieut. B.A. FISKE, U.S.N.

Lieutenant Fiske began by paying a tribute to the remarkable pioneer
efforts of Colonel Samuel Colt, who more than forty years ago blew up
several old vessels, including the gunboat Boxer and the Volta, by the
use of electricity. Congress voted Colt $17,000 for continuing his
experiments, which at that day seemed almost magical; and he then blew up
a vessel in motion at a distance of five miles. Lieut. Fiske next
referred briefly to the electrical torpedoes employed in the Crimean war
and our civil war.

At the present day, an electrical torpedo may be described as consisting
of a strong, water-tight vessel of iron or steel, which contains a large
amount of some explosive, usually gun-cotton, and a device for detonating
this explosive by electricity. The old mechanical mine used in our civil
war did not know a friendly ship from a hostile one, and would sink
either with absolute impartiality. But the electrical submarine mine,
being exploded only when a current of electricity is sent through it from
ship or shore, makes no such mistake, and becomes harmless when detached
from the battery. The condition of the mine at any time can also be told
by sending a very minute current through it, though miles away and buried
deep beneath the sea.

When a current of electricity goes through a wire, it heats it; and if
the current be made strong enough, and a white hot wire thus comes in
contact with powder or fulminate of mercury in a torpedo, an explosion
will result. But it is important to know exactly when to explode the

Book of the day: