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Scientific American Supplement, No. 401, September 8, 1883 by Various

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[Illustration]

SCIENTIFIC AMERICAN SUPPLEMENT NO. 401

NEW YORK, SEPTEMBER 8, 1883

Scientific American Supplement. Vol. XVI, No. 401.

Scientific American established 1845

Scientific American Supplement, $5 a year.

Scientific American and Supplement, $7 a year.

* * * * *

TABLE OF CONTENTS.

I. CHEMISTRY.--On the Different Modifications of Silver Bromide
and Silver Chloride.

Analysis of New Zealand Coal.

On the Determination of Manganese in Steel, Cast Iron,
Ferro-manganese, etc.

Manganese and its Uses.

Ozokerite or Earth-wax. By WILLIAM L. LAY. A valuable
and instructive paper read before the New York Academy of
Sciences.--Showing the nature, sources, and applications of this
remarkable product.

On the Constitution of the Natural Fats.

II. ENGINEERING AND MECHANICS.--Improved Spring wheel
Traction Engine.--With two engravings.

An Improved Iron Frame Gang Saw Mill.--With one large
engraving.

The Heat Regenerative System of Firing Gas Retorts.--Siemens'
principle.--As operated at the Glasgow Corporation Works.--With
two engravings.

A New Gas Heated Baker's Oven.

III. TECHNOLOGY.--How to Produce Permanent Photographic Pictures
on Terra Cotta, Glass, etc.--With recipes and full directions.

How to Make Paper Photo Negatives.--Full directions.

Some of the Uses of Common Alum.

An Improved Cloth Stretching Machine.--With an engraving.

Purification of Woolen Fabrics by Hydrochloric Acid Gas.

Apparatus for Preventing the Loss of Carbonic Acid in Racking
Beer.--With an engraving.

IV. ELECTRICITY.--Application of Electricity to the Bleaching of
Vetable Textile Materials.--With figure of apparatus.

Table Showing the Relative Dimensions, Lengths, Electrical
Resistances, and Weights of Pure Copper Wires.

V. ASTRONOMY.--The Solar Eclipse of 1883.--An interesting abstract
from a report of C. S. HASTINGS (Johns Hopkins University), of
the American Astronomical Exhibition to the Caroline Islands.

VI. NATURAL PHILOSOPHY.--Recent Experiments Affecting the
Received Theory of Music.--An interesting paper descriptive of
certain experiments by President Morton, of Stevens Institute.

The Motions of Camphor upon Water.--With an engraving.

VII. ARCHITECTURE.--Suggestions in Village Architecture.--
Semidetached villas.--Bloomfield crescent.--With an engraving.

Specimens of Old Knocking Devices for Doors.--Several figures.

VIII. ARCHAEOLOGY.--A Buried City of the Exodus.--Being an account
of the recent excavations and discoveries of Pithom
Succoth, in Egypt.--With an engraving.

The Moabite Manuscripts.

IX. AGRICULTURE. HORTICULTURE, ETC.--The Queen Victoria
Century Plant.--With an engraving.

Charred Clover.

A New Weathercock.--With one figure.

X. MISCELLANEOUS.--New Monumental Statue and Landing Place
in Honor of Christopher Columbus at Barcelona, Spain.--With an
engraving.

Scenery on the Utah Line of the Denver and Rio Grande Railway.

Captain Matthew Webb.--Biographical sketch.--With portrait.

The Dwellings of the Poor In Paris.

Shipment of Ostriches from Cape Town, South Africa.--With one
page of engravings.

* * * * *

MONUMENT TO CHRISTOPHER COLUMBUS, AT BARCELONA, SPAIN.

The cultivated and patriotic city of Barcelona is about to erect
a magnificent monument in honor of Columbus, the personage most
distinguished in the historic annals of all nations and all epochs.
The City of Earls does not forget that here the discoverer of America
disembarked on the 3d of April, 1493, to present to the Catholic
monarchs the evidences of the happy termination of his enterprise. In
honoring Columbus they honor and exalt the sons of Catalonia, who also
took part in the discovery and civilization of the New World, among whom
may be named the Treasurer Santangel, Captain Margarit, Friar Benardo
Boyl, first patriarch of the Indies, and the twelve missionaries of
Monserrat, who accompanied the illustrious admiral on his second voyage.

In September, 1881, a national competition was opened by the central
executive committee for the monument, and by the unanimous voice of
the committee the premium plans of the architect, Don Cayetano
Buigas Monraba, were adopted. From these plans, which we find in _La
Ilustracion Espanola_, we give an engraving. Richness, grandeur, and
expression, worthily combined, are the characteristics of these plans.
The landing structure is divided into three parts, a central and two
laterals, each of which extends forward, after the manner of a cutwater,
in the form of the bow of a vessel of the fifteenth century, bringing to
mind the two caravels, the Pinta and Nina; two great lights occupy the
advance points on each side; a rich balustrade and four statues of
celebrated persons complete the magnificent frontage. A noble monument,
surmounted by a statue of the discoverer, is seen on the esplanade.

[Illustration: MONUMENTAL LANDING AND STATUE TO COLUMBUS, AT BARCELONA,
SPAIN.]

* * * * *

The commission appointed in France to consider the phylloxera has not
awarded to anybody the prize of three hundred thousand francs that was
offered to the discoverer of a trustworthy remedy or preventive for the
fatal grape disease. There were not less than 182 competitors for the
prize; but none had made a discovery that filled the bill. It is said,
however, that a Strasbourg physician has found in naphthaline an
absolutely trustworthy remedy. This liquid is poured upon the ground
about the root of the vine, and it is said that it kills the parasites
without hurting the grape.

* * * * *

SCENERY ON THE UTAH LINE OF THE DENVER AND RIO GRANDE.

Mr. R.W. Raymond gives the following interesting account of the
remarkable scenery on this recently opened route from Denver to Salt
Lake:

Having just made the trip from Salt Lake City to this place on the
Denver & Rio Grande line, I cannot write you on any other subject at
present. There is not in the world a railroad journey of thirty hours
so filled with grand and beautiful views. I should perhaps qualify this
statement by deducting the hours of darkness; yet this is really a
fortunate enhancement of the traveler's enjoyment; it seems providential
that there is one part of the way just long enough and uninteresting
enough to permit one to go to sleep without the fear of missing anything
sublime. Leaving Salt Lake City at noon, we sped through the fertile and
populous Jordan Valley, past the fresh and lovely Utah Lake, and up the
Valley of Spanish Fork. All the way the superb granite walls and summits
of the Wahsatch accompanied us on the east, while westward, across the
wide valley, were the blue outlines of the Oquirrh range. One after
another of the magnificent canons of the Wahsatch we passed, their
mouths seeming mere gashes in the massive rock, but promising wild and
rugged variety to him who enters--a promise which I have abundantly
tested in other days. Parley's Canon, the Big and Little Cottonwood, and
most wonderful of all, the canon of the American Fork, form a series not
inferior to those of Boulder, Clear Creek, the Platte, and the Arkansas,
in the front range of the Rockies.

Following Spanish Fork eastward so far as it served our purpose, we
crossed the divide to the head waters of the South Fork of Price River,
a tributary of Green River. It was a regret to me, in choosing this
route, that I should miss the familiar and beloved scenery of Weber and
Echo canons--the only part of the Union Pacific road which tempts one
to look out of a car window, unless one may be tempted by the boundless
monotony of the plains or the chance of a prairie dog. Great was my
satisfaction, therefore, to find that this part of the new road,
parallel with the Union Pacific, but a hundred miles farther south,
traverses the same belt of rocks, and exhibits them in forms not less
picturesque. Castle Canon, on the South Fork of the Price, is the
equivalent of Echo Canon, and is equal or superior in everything except
color. The brilliant red of the Echo cliffs is wanting. The towers
and walls of Castle Canon are yellowish-gray. But their forms are
incomparably various and grotesque--in some instances sublime. The
valley of Green River at this point is a cheerless sage-brush desert,
as it is further north. To be sure, this uninviting stream, a couple of
hundred miles further south, having united with the Grande, and formed
the Rio Colorado, does indeed, by dint of burrowing deeper and deeper
into the sunless chasms, become at last sublime. But here it gives no
hint of its future somber glory. I remained awake till we had crossed
Green River, to make sure that no striking scenery should be missed by
sleep. But I got nothing for my pains except the moonlight on the muddy
water; and next time I shall go to bed comfortably, proving to the
conductor that I am a veteran and not a tender-foot.

In the morning, we breakfasted at Cimarron, having in the interval
passed the foot-hills of the Roan Mountains, crossed the Grande, and
ascended for some distance the Gunnison, a tributary of the Grande, the
Uncompahgre, a tributary of the Gunnison, and finally a branch, flowing
westward, of the Uncompahgre. A high divide at the head of the latter
was laboriously surmounted; and then, one of our two engines shooting
ahead and piloting us, we slid speedily down to Cimarron. It is in such
descents that the unaccustomed traveler usually feels alarmed. But the
experience of the Rio Grande Railroad people is, that derailment is
likely to occur on up-grades, and almost never in going down.

From this point, comparison with the Union Pacific line in the matter
of scenery ceases. As everybody knows, that road crosses the Rocky
Mountains proper in a pass so wide and of such gradual ascent that the
high summits are quite out of sight. If it were not for the monument to
the Ameses, there would be nothing to mark the highest point. For all
the wonderful scenery on the Rio Grande road, between Cimarron and
Pueblo, the Union Pacific in the same longitudes has nothing to show.
From an artistic stand-point, one road has crossed the ranges at the
most tame and uninteresting point that could be found, and the other at
the most picturesque.

At Cimarron, the road again strikes the Gunnison, and plunges into the
famous Black Canon. In length, variety, and certain elements of beauty,
such as forest-ravines and waterfalls, this canon surpasses the Royal
Gorge of the Arkansas. There is, however, one spot in the latter (I
mean, of course, the point where the turbulent river fills the whole
space between walls 2,800 ft. high, and the railroad is hung over it)
which is superior in desolate, overwhelming grandeur to anything on the
Gunnison. Take them all in all, it is difficult to say which is the
finer. I have usually found the opinion of travelers to favor the
Gunnison Canon. But why need the question be solved at all? This one
matchless journey comprises them both; and he who was overwhelmed in the
morning by the one, holds his breath in the afternoon before the mighty
precipices of the other. To excuse myself from even hinting such folly
as a comparison of scenery, I will merely remark that these two canons
are more capable of a comparison than different scenes usually are; for
they belong to the same type--deep cuts in crystalline rocks.

Between them come the Marshall Pass (nearly 11,000 ft. above sea-level),
over the continental divide, and the Poncha Pass, over the Sangre di
Cristo range. This range contains Harvard, Yale, Princeton, Elbert,
Massive (the peak opposite Leadville), and other summits exceeding the
altitude of 14,000 ft. To the east of it is the valley of the Arkansas,
into which and down which we pass, and so through the Royal Gorge to
Canon City and Pueblo, where we arrived before dark on the day after
leaving Salt Lake.

Salt Lake, the Jordan Valley, Utah Lake, the Wahsatch, Castle Canon, the
Black Canon of the Gunnison, Marshall Pass, Poncha Pass, the Arkansas
Valley, the Royal Gorge--what a catalogue for so brief a journey! No
wonder everybody who has made it is "wild about it!" If enthusiastic
urgency of recommendation from every passenger has any influence (and I
know it has a great deal), this road will continue to be, as it is at
present, crowded with tourists. It furnishes a delightful route for
those who wish on the overland journey to see Denver (as who does not?)
and to visit Colorado Springs and Manitou. All this can be done _en
route_, without retracing the steps.

* * * * *

PHOTOGRAPHY APPLIED TO TERRA-COTTA AND OPAL GLASS.

In the natural course of things it must necessarily have occurred to
practical men to utilize photography in the case of terra-cotta, as it
has already been employed in connection with so many other wares; but I
have not to this day known of its successful application to terra-cotta.
Now this is strange, if one considers how fashionable _plaque_ and plate
painting have become of late, and the good photographic results that
are easily obtained on these as on sundry articles of this same "burnt
earth." Portraits, animals, landscapes, seascapes, and reproductions are
one and all easily transferred, whether for painting upon or to be left
purely photographic. As a matter of business, too, one fails to see
that it would not be remunerative, but rather the contrary. It was with
something of this feeling that I was led to try and see what could be
done to attain the end in view, and as I knew of no data to go by, I had
to use my own experience, or rather experiment on my own account.

Since emulsion was constantly at hand in my establishment, in the
commercial production of my gelatine dry plates, it was but natural I
should first have turned to this as a mode of obtaining the desired
results; but, alas! all attempts in that direction signally failed--the
ware most persistently refused to have anything to do with emulsion. The
bugbear was the fixing agent or hypo., which not only left indelible
marks, but, despite any amount of washing, the image on a finished plate
vanished to nothing at the end of an hour's exposure in the show window.
There was nothing left but to seek other means for the attainment of my
object. I would not have troubled the reader as to this unsuccessful
line of experiment but that I wished to put him on his guard and save
him useless researches in the same direction. To cut matters short, the
method I found best and most direct was the now old but still excellent
wet collodion transfer. I will now proceed to detail my system of
working to facilitate the matter to the inexperienced in collodion
transfer.

TERRA-COTTA PHOTOGRAPHY IN PRACTICE.

The first and indispensable operation, in the preparation of the surface
to receive the transfer, is the "sizing of the surface." It simply
consists of a solution of gelatine chrome-alumed, as follows:

Gelatine. 10 grains.
Water. 1 ounce.
A trace of chrome alum.

Coat with a soft camel's hair brush and let dry. It is needless to say
that numbers of _plaques_, plates, vases, etc., may be coated right off,
and will then be ready for use at any time.

Having settled on the subject and carefully dusted the negative, as well
as placed it _in situ_ for reproduction, the next thing required is a
suitable collodion, and the following will be found all that can be
desired:

TRANSFER COLLODION.

Cotton. 3 drachms.
Iodide of cadmium. 65 grains.
Ammonium iodide. 25 "
Bromide of cadmium. 19 "
Ammonium bromide. 11 "
Alcohol. 15 ounces.
Ether. 15 "

The plate thoroughly cleaned and coated with the collodion is now
transferred to a bath, as follows:

Nitrate of silver (common) 25 grains to the ounce.

Made slightly acid with nitric acid.

After sensitizing, the plate is exposed in the usual way and taken to
the room where pictures are ordinarily developed, and _quantum suff_. of
the following poured into the developing cup to bring out the image:

DEVELOPING SOLUTION.

A Winchester of water, i.e. 80 ounces.
Protosulphate of iron. 240 grains.
Citric acid. 240 "

Or the following may be used:

Pyro 3 grains\
Citric acid 2 " } per ounce of water.
Glacial acetic acid 30 drops /

After perfect development the picture is well washed and then fixed in a
saturated solution of hypo.; after which it is thoroughly washed.

It will now be found that the picture is not altogether satisfactory; it
lacks both vigor and color. To improve matters recourse is now had to

TONING.

Gold. 1 grain.
Water. 5 ounces.

With this a very fine depth is soon attained, and a nice picture the
result. Leave out the toning, and only a poor, sunken-looking picture
will be the outcome; but directly the toning bath is employed richness
at once comes to the fore. I have, however, known of instances where the
picture needed no toning.

OPAL PRODUCTION IN PRACTICE.

This is still a secret with some in the profession. A limited number
of workers have succeeded in bringing out good opals, and their _modus
operandi_ is kept from the many. Now this is a pity, when one considers
the great charm attached to a good picture on opal, with pure whites and
rich blacks, and in many localities the demand that might be created for
them. Apart from their beauty, another charm attaches to opals--their
absolute permanence; and this, it must be allowed, is no trifle. What,
in fact, can be more painful to the worker who values his work, and sets
store by it, than to feel it must ere long fade and pass into oblivion!
A properly executed opal will no more fade than the glass pictures so
common at one time, and which, wherever taken care of, are as perfect
now as they were when first taken.

Now, excellent pictures are to be made on opals by means of emulsion;
but I propose first taking the transfer method (mainly applicable to
ground opal and canvas) as given above for pottery, since in practice
it is found very ready, easy of manipulation, and safe. The details are
much the same as above, and necessitate double transfer.

After the picture had been obtained on the plate (ordinary glass plate),
and after thoroughly fixing, washing, and toning, the picture (and this,
remember, is the case likewise with terra-cotta) then has to be loosened
from its support, and this is done with a solution of sulphuric
acid--one drachm to fifteen ounces of water--which is made to flow
between the image and the glass, after which perfectly wash and mount.
When the image is loosened a piece of tracing paper is put on the image,
evened out, raised (assisted by some one else to hold the two opposite
corners during the operation), and with the aid of the helper the
picture is carefully centered, gently pressed out or down, and the
transfer is so far effected. But what will happen, and does happen,
in the case of vignettes, is impurity of the whites, when the picture
becomes positively objectionable. Now the way to remedy this lies simply
in the application, to the dirty-looking parts, of a solution of iodine
dissolved in iodide of potassium to sherry color; after which, well wash
and apply a weak solution of cyanide of potassium, and wash well again.
This, by the way, is equally applicable to paper transfers; and it is
to be remembered that the toning comes last of all. It is a rather
difficult matter to clean a ground opal which has been used two or three
times, and acid must then be had recourse to (nitric acid is as good as
any); but by transferring from the support on the ground surface, all
stains are at once avoided.

On the flushed glass, or on the pot metal (unground), after well
cleaning the surface it should be covered with a substratum of egg. Then
the picture is taken direct, not transferred; that is, the plate is
exposed direct in the camera, regularly proceeded with, and, when dried,
varnished with a pale negative varnish, or with dead varnish if intended
for chalk or water-color. This, when a good negative is used, gives a
remarkably fine picture, not requiring a vestige of retouching, and
having likewise the invaluable advantage of being perfectly durable
if varnished with the negative varnish. Moreover, on that, effective
pictures may be made in oil with simply tinting.

A gentleman, who has a right to be considered a good judge in all art
matters, on looking at one of these pictures transferred on flushed
glass, said it was one of the finest productions of photography. He
urged that negatives _ad rem_ should be taken most carefully, and that,
like the picture I showed him, they should be full of half-tone and
detail, and yet have plenty of vigor. They should, he said, be robust in
the high lights, have perfectly clear glass in the few points of deep
shadows, and thus have powerful relief. Moreover, the negatives should
be retouched only by a competent hand, and care taken that the likeness
shall be in no way altered, which is so frequently the case now.

If done as thus suggested there is no doubt that remarkably fine
pictures are to be produced on opal, whether ground or not. Most
artistic results are to be obtained, and, with proper care, absolute
permanency. In this age of keen competition, all have to think of what
may be really recommended to one's _clientele_, and likely to meet with
approbation from strangers and friends when the picture has once been
delivered; and I candidly think that the opal, of all, is the picture
most likely to meet with this general approbation.

I hope I have left it clearly to be understood that the class of opal
picture to which I have chiefly alluded is one that remains untouched
after the transfer--that is, absolutely unpainted upon. It is pure
photography in every sense of the word, and the resultant picture one
hardly to be surpassed in any way. I have rather laid a stress on this
point, well knowing how pictures are at times irretrievably ruined by
the barbarous hand of would-be artists, who by far exceed the true
artists in number; and the hint on retouching should not be lost sight
of, either, at a period when the tendency is to stereotype every one
in marble-like texture, or rather lack of texture, as if the face were
devoid of all fleshiness and as hard and rigid as cast-iron. It might
be wise to weigh this point carefully, and act upon it, before the
enlightened public have raised a cry against the pernicious practice
and made photographers smart for their want of applying timely remedial
measures to a decided evil.

On reading the above again, fearing lest any misconception should arise
in the mind of the reader, I deem it expedient, to clearly state that
for terra-cotta recourse is had to double transfer; that is, the picture
first taken is lifted from the support on tracing paper, put in
the right position on terra-cotta, and pressed down while wet with
blotting-paper, left to dry, and is then so far ready.

Respecting the production of pictures by means of emulsion, ground opal
being the best, the system I employ is as follows: After well cleaning
the glass, coat it with emulsion (which had better not be too thick).
When dry it is exposed and developed with the usual oxalate developer,
to which a little bromide of potassium has been added. The remainder of
the operations is as usual. Those varnished with dead varnish can be
tinted and worked up with colored crayons or black lead pencil and make
very pleasing pictures. It is needless to add that they are also to be
finished in water-colors if thought preferable.--_G. W. Martyn, in Br.
Jour. Photo_.

* * * * *

PAPER NEGATIVES.

The process of A.C.A. Thiebaut is as follows: the paper has the
following advantages:

First. The sensitive coating is regular, and its thickness is uniform
throughout the entire surface of each sheet.

Second. It can be exposed for a luminous impression in any kind of slide
as usually constructed.

Third. It can be developed and fixed as easily as a negative on glass.

Fourth. The negative obtained dries quite flat on blotting paper.

Fifth. The film which constitutes the negative can be detached or peeled
from its support or backing easily and readily by the hand, without the
assistance of any dissolving or other agent. Thus this invention does
away with all sensitive preparations on glass, which latter is both a
brittle and relatively heavy material, thus diminishing the bulk and
weight of amateur and scientific photographers' luggage when traveling;
it produces photographic negatives as fine and as transparent as those
on glass, in so much that the film does not contain any grain; and,
lastly, it admits of printing from either face of the film, as regards
the production of positives on paper or other material, as well as
plates for phototypy and photo-engraving, which latter processes require
a negative to be reversed.

For the manufacture of my sensitized film paper:

First. A gelatinized sheet of paper is properly damped with cold water,
and when evenly saturated it is placed on a glass, to which it is
attached by means of bands of paper pasted partially on the glass, and
partially on the edges of the said sheet; in this state it is allowed to
dry, whereby it is stretched quite flat.

Secondly. I coat the dry sheet with a solution of ordinary collodion,
containing from one to two per cent. cubic measure of azotic cotton (11/2
per cent. gives very good results) and from 11/2 to 21/2 per cent. of castor
oil (2 per cent. gives very good results); this coating is allowed to
dry; and,

Thirdly. The glass, with the prepared paper upward, is leveled, and then
it is coated, in a room from which all rays but red rays of light are
excluded, with a tepid emulsion of bromide of silver to the extent of
about one millimeter thick, and after leaving it in this position until
the gelatine has set (say) about five minutes, with the film paper still
attached, it is placed upright in a drying-room, where it should remain
about twelve hours exposed to a temperature of from 62 to 66 degrees
Fahrenheit; and,

Fourthly. The film paper is detached from the glass ready for exposure,
development, and fixing in the usual manner. For the purpose of
developing, oxalate of iron or pyrogallic acid answers equally well; for
the purpose of fixing, I have found that a mixture by weight, water,
1,000, hyposulphite of soda 150, and powdered alum 60, produces
excellent results, after being allowed to dry.

Fifthly. The film is peeled off the paper by hand, and can be
immediately used for producing negatives _recto_ or _verso_ as above
mentioned.

I claim as my invention:

First. The preparation or formation of gelatino-bromide film paper
for photographic negatives, in the manner and for the purposes above
described; and,

Secondly. The use for this purpose of castor oil, or any other analogous
oil, more especially with the view of peeling off the film from the
paper backing as above described.

* * * * *

SOME OF THE USES OF COMMON ALUM.

A substance very much used by photographers of late years--in fact, so
much used that no well-appointed laboratory could be considered complete
without it--is the substance known is common alum, or potash alum, being
a double sulphate of alumina and potash; but it is interesting to note
that much of the commercial alum met with at the present time is ammonia
alum, or the double sulphate of alum and ammonia. It is quite a matter
of indifference to the photographer whether he uses potash alum or
ammonia alum.

Besides its great value to the autotype, Woodburytype, and mechanical
printers as an agent for hardening the gelatine films, it has been
recommended for all sorts of ailments photographic. The silver printer
adds a small portion to his sensitizing bath to keep it in working
order, and to prevent blistering of the albumen; then, again, silver
prints are soaked in a dilute solution of alum, having for its object
the thorough elimination of the last traces of the fixing salt. A very
good proportion to use for this latter purpose is four fluid ounces of a
saturated solution, diluted with one gallon of water, the prints being
well agitated during an immersion of ten minutes.

Of all the uses to which alum is put, perhaps not in any single instance
can so much satisfaction be derived as when it is used to
arrest frilling of gelatine plates. This it has the power to do
instantaneously, and many of the most careful workers, both amateur and
professional, or at least those who do net care to run any unnecessary
risks with negatives which have cost them a good deal of anxiety and
trouble to secure, but prefer to make assurance doubly sure--such
individuals may be numbered by the hundred--make it a point in every-day
practice to immerse all their plates in a solution of alum, either
before fixing, or immediately afterward. In fact, some operators have
two alum baths in use, one a normal bath, as above mentioned, for
immersing the plates in when of the ordinary printing intensity; and the
other a saturated solution strongly acidified by means of a vegetable
acid (such as citric) or a mineral acid (such as sulphuric), for use
when there is too much printing density, since it has been found
in practice that an acid solution of alum in contact with sodium
thio-sulphate on the gelatine image (after fixing, but before washing)
not only removes the color or stain caused by the alkaline or
pyrogallol, but perceptibly reduces the strength of the image. Moreover,
the color does not again reappear after washing, as it does sometimes
when the fixing salt has been partially washed away. In cases where
there is great tendency to frill--such, for instance, as when a soft
sample of gelatine has been employed, or old decomposed emulsion worked
in with the fresh emulsion--it will in such cases be safer to put the
plates in the normal-bath for a few minutes previous to immersing them
in the acid bath.

Potash alum is obtained tolerably pure in commerce in colorless
transparent crystalline masses, having an acid, sweetish, astringent
taste. It is soluble in 18 parts of water at 60 deg. F., and in its own
weight of water at 212 deg. F.; but the excess crystallizes out upon
cooling. The solution reddens litmus paper, and, when impure, usually
contains traces of oxide of iron. Upon the addition of either caustic
soda or potash, a white gelatinous precipitate is formed (hydrate of
alumina), which is soluble in excess of the reagent employed. The
precipitate thus obtained has much of the character of the opalescent
film sometimes observed on gelatine plates, when dry, which have been
soaked in alum, and not well washed afterward.

Alkaline carbonates--such as washing soda, for instance--precipitate
hydrate of alumina, which does not dissolve in an excess of the
reagents, and carbon dioxide is evolved.

Ammonia hydrate produces a precipitate in a much finer state of divison,
which does not dissolve in excess when examined in a test-tube, it
somewhat resembles thin starch paste.

The presence of traces of iron may be known by adding a few drops of
hydrochloric acid to a small quantity of a saturated solution of alum
in a test-tube, to which add strong liquid ammonia; should any iron be
present, the mixture will have a reddish-brown tinge when examined over
a sheet of white paper. Other alums exist, such as the double sulphate
of alumina and sodium, and sodium or aluminum and ammonium; but hitherto
their uses have been confined to the experimental portion of the
community rather than the practical.--_Photo. News_.

* * * * *

CLOTH STRETCHING MACHINE.

As is well known, in the process of bleaching and dyeing, cotton cloths
become considerably contracted in the width, in consequence of carrying
on the operations when the cloth is in the form of a rope. The effect is
that, together with the tension, although slight, and the drying, the
weft partly shrinks and partly curls up, the latter, however, being
scarcely observable to the naked eye. It may almost be said that as
regards the width the shrinkage is due to a number of minute crumples
because the cloth is easily streatched again by the fingers almost to
its gray width. The main use of a stretching machine, therefore, is not
so much to make the cloth more than it is as to bring it again to its
normal or woven width after operations that tend to shrinkage have been
performed upon it. The stretching operation, therefore, is especially
useful to calico printers, as it enables them to obtain when desired a
white margin of even width, the irregularities due to bleaching being
corrected before printing.

[Illustration: IMPROVED CLOTH STRETCHING MACHINE.]

The machine now illustrated is one we have recently seen in operation in
a Salford finishing works. It is an improved form of another stretching
machine which had been turned out in considerable numbers by Mr.
Archibald Edmeston, engineer, of Salford, who makes a specialty of
calico printers' and finishers' machinery. The improvements consist
mainly of a simplification of the working parts and thoroughly
substantial construction of the machine. The principle adopted is a
well-known one. The selvages of the cloth, or more strictly the two
edges of the cloth, of a width of about two inches, are caused to pass
over and at the same time are held by the rims of two diverging pulleys.
The rims are further apart where the cloth leaves them than where they
seize it, hence the stretching is gradually, certainly, and uniformly
performed. The cloth is gripped by the pressure of an endless belt
acting against the lower half of each pulley, the edges being held
between them. In the engraving these stretching pulleys are indicated by
the letters AA; the endless leather band passes over the pulleys, CC, of
which there are a set of four provided for each stretching pulley. The
lower pair of pulleys in each case may be tightened up by a screw
for the purpose of imparting the requisite tension to the bands. The
stretching pulleys are mounted upon and driven by the same shaft, an
ingenious but simple swiveling joint in their bosses enabling them to
be set at any angle to the shaft and yet to revolve and be driven by it
without throwing any undue strain upon the working parts. The piece,
wound upon the ordinary batch shell, is placed upon the running-off
center, D; it is led off over the rails, EE, and then downward to the
nip of the bands and pulleys, AA. As explained, the selvages are here
gripped between the bands and stretching pulleys, the rims of which are
wider apart at the back than the front, and thus, in being conveyed
underneath, the piece is suitably stretched. Leaving the grip at the
back it passes over leading-off rollers, FF, and the scrimp or opening
rail, G, and thence downward to the winding-on center, which cannot be
seen. The winding-on center is driven by friction. As the batch fills
it and tends to wind faster than the machine delivers the cloth, the
driving slips. In addition to a capability of being set at an angle to
the shaft, the stretching pulleys, AA, may be slided upon, so as to
separate or bring them closer together, to allow for the treatment of
different widths of cloths. This adjustment is provided for by mounting
the stretching pulleys, AA, and the band pulleys, CC, etc., on frames,
BB, the ends of which rest, as shown, upon rails, at the back and front
of the machine. The adjustment either for width of piece or for the
angularity (extent of stretching) is easily made by the hand-wheel, L.
By the bevel wheels shown, two cross screws having nuts connected to the
ends of frames, BB, are actuated in such a way that as desired the space
between the back and front of the pulleys may be closed in or opened
out, or the two wheels, maintaining the same angularity, may be
separated or closed in, either adjustment being expeditiously made. The
wheels, HHH, are called center stretching wheels, the use of which is
sometimes advantageous. They act in conjunction with a set of stretching
pulleys, of which one, K, may be seen in illustration. By a proper
adjustment at the latter the piece is bent into a wavy form, where it
passes between the whole of them, the effect of the corrugation being
to loosen the center threads and to allow the piece to be more equally
stretched with those near the selvages and more easily. This part of the
machine may be used or not as required. The production, we observe, was
about 120 yards per minute. The machine is solidly built and well fitted
together, as was obvious to us from an inspection of some in course
of construction at the maker's works. It is also claimed to be of
considerable advantage to bleachers and finishers of white goods,
on account of the uniformity of the stretching causing but small
disturbance to the stiffening.--_Textile Manufacturer_.

* * * * *

WOOLEN FABRICS PURIFIED BY HYDROCHLORIC ACID GAS.

All known methods for chemically purifying woolen stuffs from vegetable
fibers depend on the action of acids or substances of acid reaction.
The excessive temperature, hitherto unavoidable in the operation, acts
injuriously on the woolen fibers, especially during the formation of
hydrochloric acid, with which process especially the development of an
injuriously high temperature has been hitherto unavoidable. The best
method of absorbing the heat developed is in the evaporation of the
moisture naturally present in the wool. The patentees find agitation of
the fabric and the use of an exhauster during the process of material
assistance. The operation maybe successfully performed in two
ways--either by acting on the fabric at the ordinary pressure with
constant agitation, or by saturation without agitation in a vacuum. For
the first method the patentees employ a wooden cylinder with an aperture
at one end for inserting and removing the cloth, and having apertures
all round to allow free access of air. This cylinder rests on a hollow
axle, closed at one end and perforated with holes, through which the
acid gas is passed. By the rotation of the cylinder the gas is drawn
through the material and the latter exposed to the atmosphere, whereby
it gives up a quantity of aqueous vapor. An average temperature of 30 deg.
Cent. is best suited to the operation, and it can be regulated according
to the supply of gas by opening or shutting a three-way cock between the
gas generator and the revolving cylinder. This process is assisted by
the use of an exhauster of the usual construction. When fully saturated,
the fabric is allowed to remain until the vegetable fibers are
sufficiently friable. The treatment _in vacuo_ is as follows:

The hydrochloric acid gas passes into a vessel of suitable material
provided with a perforated false bottom. From under this false bottom
a pipe connects with a second similar vessel connected itself with a
vacuum pump having a let-off pipe. As soon as the maximum vacuum is
attained, the gas is turned on through a three-way cock at a pressure of
40 mm. mercury. The gas fills the first vessel and saturates the cloth.
The warmth set free (about 500 calories per kilo, gas) is taken up
by the combined water in the wool, as, owing to the low pressure, a
quantity of vapor is formed sufficient to take up the heat. This vapor
streams through the second vessel at a temperature of 35 deg. Cent.,
penetrates the material, and passes out through the pump. After
saturating the contents of the first vessel the gas passes into the
second. AS soon as this is one-quarter or one-third saturated the first
vessel is taken out and replaced by a third, which receives the overplus
from No. 2 in like manner, and so on. This plan of working prevents gas
passing through and damaging the pump. Instead of working under reduced
pressure, the desired low temperature can be maintained by passing
alternately with the gas currents of air which absorb heat in
evaporating the moisture of the material. The cloth, after saturation by
these processes, is left from six to twelve hours in the vessels, after
which it is freely exposed to the air until the vegetable particles
are friable. As soon as this occurs, the fabrics are washed. It is
advantageous to add to the wash water powdered carbonate of baryta,
strontia, magnesia, or preferably lime, and subsequently to rinse in
pure water. Phosphate of lime containing carbonate may also be employed
for neutralizing the acid, and the residue recovered and separated from
the organic residues mixed with it.--"_H. J.," Journal of the Society of
Chemical Industry._

* * * * *

APPLICATION OF ELECTRICITY TO THE BLEACHING OF VEGETABLE TEXTILE
MATERIALS.

It is a recognized fact that chemical bodies in a nascent state are
characterized by peculiarly energetic affinities, and the results of
numerous experiments permit us to affirm that animal and vegetable
fibers are rapidly bleached when they are placed in contact with oxides
and chlorides which, when submitted to electrolysis, permit oxygen and
chlorine to disengage themselves in the nascent state.

The coloring matter that impregnates the majority of vegetable textile
substances, such as cotton, flax, and hemp, to cite only those most
generally known, is in fact completely destroyed only by the combined
action of oxygen and chlorine, which always act in the same manner,
whether the fibers be in a raw or woven state.

In the application of electrolysis to the bleaching of textile
materials, it is only necessary to have the electrodes of any
sufficiently powerful generator of electricity end in a vessel
containing in aqueous solution such decolorizing agents as the
hypochlorites in general, and chlorides, bromides, and iodides that are
capable of disengaging chlorine, and iodine or an iodide in a nascent
state. These gases perform the role of oxidizing or decolorizing agents.

The fibers that are immersed in the solution during the passage of the
electric current must necessarily remain therein for a greater or less
length of time, according to the nature of the material to be bleached,
and must, after this first operation, be washed, rinsed, and dried.

The use of an electric current for decomposing the metallic chlorides
and disengaging their elements is not new, and there have been specially
utilized for this purpose, up to the present time, the alkaline
hypochlorites that are obtained by well known processes.

In the latter case the metal is brought to the state of oxide in
presence of the water that is necessary for the reaction. But the
results obtained in practicing this method are deceiving, as far as
bleaching is concerned, and it is evidently more rational and economical
to endeavor to compound the hypochlorite directly by borrowing all its
elements from the metallic chloride itself, and from the water by means
of which such transformation is to be effected. This is a reversal of
the problem, and, _a propos_ thereof, we would call the attention of
the reader to an apparatus invented by Messrs. Naudin & Schneider for
effecting such synthesis in a simple and practical manner.

If a solution of chloride of sodium or kitchen salt, NaCl, be submitted
to electrolysis in a hermetically closed vessel containing the material
to be bleached, a formation of hypochlorite of soda is produced in the
following way:

2NaCl + 2 H_{2}O = NaCl + NaO, ClO + 4H.

In operating in this manner we shall have the advantage that results
from the nascent body through the electrical double decomposition of the
chloride of sodium and water, which puts the chlorine, the metal, the
hydrogen, and the oxygen simultaneously in presence. The chlorine and
oxygen will combine their action to decolorize the textile material.

While starting from this idea, it will nevertheless be preferable to
adopt Naudin & Schneider's arrangement.

The apparatus consists of a hermetically closed electrolyzer, A,
into the lower part of which enters the electrodes, E and F, of any
electrical machine whatever. The receptacle, A, is provided with a
safety-tube, T, that issues from its upper part and communicates with
a reservoir, B. A second tube, D, forms a communication between the
electrolyzer and the vessel, C. The liquid contained in this latter is
sucked up by a pump, P, and forced to the lower part of the vessel, A,
by means of the tubes, G and H.

The apparatus operates as follows:

The closed vessel, C, in which the material to be bleached is put, is
filled, as is also the electrolyzer, with a solution of chloride of
sodium. This solution is then submitted to the action of an electric
current, when, as a consequence of the chemical decomposition of
the chloride and the water, the elements in a nascent state form
hypochlorite of soda. When the partial or total conversion of the liquid
has been effected (this being ascertained by chlorometric tests), the
pump, P, is set rapidly in operation, and, as a consequence, draws up
the chloride of sodium from the bottom of the vessel, C, to the lower
part of the electrolyzer, A. The hypochlorite that has formed passes
through the tube, D (as a natural consequence of the elevation of the
level of the liquid in A brought about by the entrance of a new supply
of chloride), and distributes itself throughout the vessel, C, where it
acts upon the textile material.

[Illustration: APPARATUS FOR BLEACHING TEXTILE FIBERS BY ELECTRICITY.]

The safety-tube, T, which is attached to the electrolyzer, permits
of the escape of the hydrogen which is produced during the chemical
reaction, and fixes, through an alkaline solution contained in the
reservoir, B, the chloride whose escape might discommode the operator.

As may be conceived, the slow transfer of the saline solution from
the receptacle, C, to the electrolyzer, and its rapid conversion into
decolorizing chloride, as well as its prompt application upon the
materials to be bleached, presents important advantages.

While, in the present state of the industries that make use of bleaching
chlorides, the chloride of sodium is converted into hydrochloric acid,
which, in order to disengage chlorine, must in its turn react upon
binoxide of manganese, we shall be able, with this new method, to
utilize the chloride of sodium, which is derived from ordinary salt
works, and extract from it the constituent elements of the hypochlorite
by a simple displacement of molecules produced under the influence of an
electric current.

Another and very serious advantage of electric bleaching is that of
having constantly at hand a fresh solution of hypochlorite possessing a
uniform decolorizing power, which may be regulated by the always known
intensity of the current.

We must remark that the hypochlorites require a certain length of time
to permit the chlorine to become disengaged, and that, besides, all
chlorides, bromides, and iodides that are isomorphous are capable of
undergoing an analogous chemical transformation and of being employed
for the same purpose. This is especially the case with the chlorides
of potassium or barium, the bromides of strontium or calcium, and the
iodides of aluminum or magnesium. On another hand, as sea water contains
different chlorides, it results that it might serve directly as a raw
material for bleaching textile fibers. Then, when the solution of
chloride of sodium has been deprived of its chlorine by electrolysis,
there remains a solution of caustic soda which may be utilized for
scouring fibers.--_H. Danzer, in Le Genie Civil_.

* * * * *

IMPROVED SPRING TRACTION ENGINE.

Messrs. J. & H. McLaren, of the Midland Engine Works, Hunslet, Leeds,
England, for several years past have devoted considerable attention to
the question of mounting traction engines on springs. The outcome of
this is the engine in question, the front end of which is carried by a
pair of Timmis spiral springs, resting on the center pin of the front
axle, which is on Messrs. McLaren's principle, which enables it to
accommodate itself to the inequalities of the road without throwing any
undue strain on the front carriage. The chief difficulty hitherto has
been to mount the hind end on springs without interfering with the spur
gearing, which must be kept perfectly rigid to prevent breakage of the
cogs. This is entirely provided for by the new arrangement, whereby all
the spring is allowed for in the spokes of the wheel itself, which will
be clearly seen on reference to the illustrations, in which Fig. 1 is a
perspective view of the engine, while Fig. 2 shows a detail view of the
wheel. The rim of the wheel is built up in the ordinary way of strong
T-iron rings, with steel crossplates riveted on. The nave of the wheel
has wrought-iron ribs to which the spokes are bolted. These spokes are
made of the best spring steel, specially manufactured and rolled for the
purpose, 9 inches wide and 1/2 inch thick. They are bent in a pear shape,
with the narrow ends fastened to the nave, and the crown resting upon
the rim of the wheel, where they are divided, and held in their places
by means of clip fastened with bolts. When the weight of the engine
comes on these spokes, those nearest the ground are compressed and
those, at the top are elongated a little. In order to avoid any of the
driving strain passing through the springs, a strong arm is fixed on the
differential wheel and attached to the rim as shown in Fig. 2, so that
the springs have really no work to do beyond carrying the weight of the
engine. Messrs. McLaren naturally felt a certain amount of diffidence
in placing their invention before the public until they had thoroughly
tested it in practical work. This, we are informed, they have done, with
the most satisfactory results, during the last five or six months; and
they have a set of springs which ran during that time between 2,000 and
3,000 miles, besides which there are several of these spring engines in
daily use.--_Iron_.

[Illustration: FIG 1. IMPROVED SPRING TRACTION ENGINE.]

[Illustration: FIG. 2]

* * * * *

TABLE SHOWING THE RELATIVE DIMENSIONS, LENGTHS, RESISTANCES, AND WEIGHTS
OF PURE COPPER WIRE.

DIAMETER | AREA
|
B.W.G Inch. Milli- | Circu- Square Square
No. metres | lar inches. Milli-
| Mils. metres.
|
0000 .454 11.5313 | 206116 .161883 10.4435
000 .425 10.795 | 180625 .141862 9.152
00 .38 9.6518 | 144400 .113411 7.3165
0 .34 8.6358 | 115600 .0907922 5.8573
1 .3 7.620 | 90000 .070686 4.5602
2 .284 7.2134 | 80656 .0633472 4.0867
3 .259 6.5784 | 67081 .0526854 3.3989
4 .238 6.0451 | 56644 .0444881 2.8701
5 .22 5.5879 | 48400 .0380133 2.4523
6 .203 5.1561 | 41209 .0323655 2.088
7 .18 4.5719 | 32400 .0254469 1.6417
8 .165 4.1909 | 27225 .0213825 1.3794
9 .148 3.7591 | 21904 .0172034 1.1098
10 .134 3.4035 | 17956 .0141026 .9096
11 .12 3.0479 | 14400 .0113097 .7296
12 .109 2.7701 | 11881 .00933133 .60199
13 .095 2.4129 | 9025 .0070882 .4573
14 .083 2.1082 | 6889 .00541062 .34906
15 .072 1.8288 | 5184 .00407151 .2486
16 .065 1.6510 | 4225 .00331831 .21407
17 .058 1.4732 | 3364 .0026421 .17045
18 .049 1.2446 | 2401 .00188574 .12165
19 .042 1.0668 | 1764 .00138544 .0894
20 .035 0.8890 | 1225 .000962115 .06207
21 .032 0.8128 | 1024 .00080425 .05188
22 .028 0.7112 | 784 .000615753 .03972
23 .025 0.635 | 625 .00049087 .03167
24 .022 0.5588 | 484 .000380133 .02452
25 .02 0.508 | 400 .00031416 .02027

26 .018 0.4571 | 324 .000254469 .01642
27 .016 0.4064 | 256 .000201062 .01297
28 .014 0.3556 | 196 .000153938 .00993
29 .013 0.3302 | 169 .000132732 .00856
30 .012 0.3048 | 144 .000113097 .007296

LENGTH AND WEIGHT

B.W.G Pounds Pounds Pounds Pounds Feet Yards 1.000 feet Miles
No. per per per 1.000 per per lb. per lb. per lb. per lb.
foot. Yard ft. mile.

0000 .623924 1.871772 623.924 3294.32 1.60276 .534253 .00160276 .00303553
000 .54676 1.64028 546.76 2886.89 1.82895 .60965 .00182895 .0034639
00 .437105 1.311315 437.105 2307.92 2.28777 .76259 .00228777 .004333
0 .349928 1.049784 349.928 1847.62 2.85773 .9525766 .00285773 .0054124
1 .272435 .817305 272.435 1438.43 3.6706 1.22353 .0036706 .0069519
2 .244151 .732453 244.151 1289.11 4.0958 1.365266 .0040958 .0077573
3 .203058 .609174 203.058 1072.15 4.9247 1.641566 .0049247 .009327
4 .171463 .514395 171.465 905.333 5.8321 1.944033 .0058321 .0110457
5 .14651 .43953 146.510 773.56 6.8255 2.275166 .0068255 .012927
6 .124742 .374226 124.742 658.638 8.0165 2.672166 .0080165 .015183
7 .098076 .294228 98.076 517.844 10.1962 3.39873 .0101962 .019311
8 .082411 .247233 82.411 435.135 12.1345 4.04483 .0121345 .022981
9 .066305 .198915 66.305 350.089 15.0818 5.027266 .0150818 .028564
10 .054354 .163062 54.354 286.99 18.398 6.13266 .018398 .034845
11 .04359 .13077 43.590 230.152 22.9413 7.6471 .0229413 .04345
12 .035964 .107892 35.964 189.893 27.805 9.2683 .027805 .05266
13 .027319 .081957 27.319 144.245 36.6046 12.20153 .0366046 .069326
14 .020853 .062559 20.853 110.1088 47.954 15.98466 .047954 .09082
15 .015692 .047076 15.692 82.855 63.7267 21.24223 .0637261 .12069
16 .012789 .038367 12.789 67.5276 78.1902 26.0634 .0781902 .14809
17 .0101828 .0305484 10.1828 53.7665 98.202 32.734 .098203 .18589
18 .00726795 .02180388 7.26796 38.3748 137.590 45.8633 .137590 .260587
19 .00533972 .01601916 5.33972 28.1937 187.276 62.4253 .187276 .35469
20 .00370815 .01112445 3.70815 19.579 269.676 89.892 .2696676 .51075
21 .00309972 .00929910 3.09972 16.3665 322.610 107.5366 .322610 .61100
22 .00237312 .00711936 2.37312 12.5301 421.384 140.4613 .421334 .798078
23 .0018910 .0056757 1.8919 9.9892 528.570 176.190 .528570 .100108
24 .0014650 .0043950 1.4650 7.7357 682.55 227.5166 .68255 .129271
25 .00121082 .00363246 1.21082 6.39315 825.880 275.2943 .825883 .156417
26 .00098077 .00294231 .98077 5.17844 1019.61 339.870 1.01961 .193108
27 .00077492 .00232476 .77492 4.0916 1290.44 430.1466 1.29044 .24440
28 .0005933 .0017799 .5933 3.13264 1685.48 561.8266 1.68548 .31922
29 .000511571 .001534713 .511571 2.7011 1954.76 651.5866 1.95476 .370220
30 .0004359 .0013077 .4359 2.30152 2294.13 764.710 2.29413 .434496

LENGTH AND RESISTANCE

B.W.G Feet Yards 1.000 feet Miles Ohms Ohms Ohms Ohms
No. per Ohm. per Ohm. per Ohm. per Ohm. per foot. per yard. per 1.000 per mile.
foot.

0000 19966.5 6655.5 19.9665 3.7815 .000050684 .00156252 .050084 .264443
000 17497.15 5832.3833 17.49715 3.31385 .0000571522 .0001714566 .0571522 .301763
00 13988.64 4662.68 13.98804 2.64925 .000071489 .000214467 .071489 .377465
0 11198.17 3732.7333 11.19817 2.12086 .0000893002 .0002679006 .0893002 .471505
1 8718.30 2906.10 8.71830 1.6512 .00011470 .0003441 .114701 .60562
2 7813.50 2604.50 7.81350 1.47973 .00012799 .00038397 .12799 .67580
3 6498.14 2166.0466 6.49814 1.23071 .00015389 .00046167 .15389 .81254
4 5487.107 1829.0357 5.487107 1.03923 .000182245 .000546735 .182245 .962256
5 4688.51 1562.8366 4.68851 .887975 .000213287 .000639861 .213287 1.12616
6 3991.91 1330.6366 3.99191 .756045 .000250506 .000751518 .250506 1.32267
7 3138.59 1046.1966 3.13859 .59443 .000318614 .000955842 .318614 1.68228
8 2637.29 879.0966 2.63729 .499486 .000379177 .001137531 .379177 2.00206
9 2121.84 707.280 2.12184 .401864 .000471289 .001413867 .471289 2.488405
10 1739.40 579.80 1.73940 .329432 .000574911 .001724733 .574911 3.03553
11 1394.93 464.9766 1.39493 .264191 .000716882 .002150646 .716882 3.78514
12 1150.91 383.6366 1.15091 .217976 .000868875 .002606625 .868875 4.58766
13 874.252 291.4173 .874252 .165578 .00114383 .00343149 1.14383 6.03945
14 667.338 222.446 .667338 .12639 .00149849 .00449547 1.49849 7.91203
15 502.175 167.39166 .502175 .095109 .00199134 .00597402 1.99134 10.5142
16 409.276 136.42533 .409276 .077514 .00244334 .00733002 2.44334 12.9008
17 325.871 108.62366 .325871 .061718 .0030687 .0092061 3.0687 16.20274
18 232.585 77.52833 .232585 .04405 .0042995 .0128985 4.2995 22.7014
19 170.879 56.95966 .170879 .032363 .0058521 .0175563 5.8521 30.8991
20 149.3915 49.797166 .1493915 .022475 .00842703 .02528109 8.42703 44.4947
21 99.195 33.065 .099195 .018787 .01008110 .03024348 10.08116 53.2285
22 75.9461 25.315366 .0759461 .014384 .0131672 .0395016 13.1672 69.5230
23 60.54377 20.181256 .06054377 .011467 .0165170 .0495510 16.5170 87.2096
24 46.8851 15.628356 .0468851 .0088798 .02132874 .06398622 21.32874 112.616
25 38.748 12.916 .038748 .0073386 .025808 .077424 25.808 136.265
26 31.3859 10.461966 .0313859 .0059443 .03186144 .09558432 31.86144 168.229
27 24.79873 8.266243 .02479873 .0046967 .0403246 .1209738 40.3246 212.914
28 18.98653 6.328843 .01898653 .0035959 .05266892 .15800676 52.66892 278.092
29 16.3710 5.4570 .0163710 .0031006 .0610834 .1832502 61.0834 322.521
30 13.9493 4.649766 .0139493 .0026419 .07168825 .21506475 71.68825 378.514

RESISTANCE & WEIGHT

B.W.G Ohms Lbs.
No. per lb. per Ohm.

0000 .000080272 12457.5
000 .000104529 9566.7
00 .000163553 6114.24
0 .000255196 3918.58
1 .00042102 2375.18
2 .00052422 1907.59
3 .00075786 1319.50
4 .0010629 940.844
5 .0014558 686.911
6 .0020082 497.96
7 .00324863 307.822
8 .00460101 217.343
9 .00710791 140.689
10 .0105772 94.543
11 .0164462 60.842
12 .0241593 41.392
13 .0418692 23.8839
14 .0718583 13.9163
15 .126788 7.8872
16 .191045 5.2344
17 .301355 3.31835
18 .59157 1.6904
19 1.09596 .912445
20 2.27254 .44003
21 3.25229 .30748
22 5.54843 .18023
23 8.73035 .11454
24 14.5579 .068691
25 21.3142 .046917
26 32.4863 .030782
27 52.0367 .019217
28 88.7724 .011265
29 119.404 .008375
30 164.4762 .0060804

PURE COPPER weighs 555 lbs. per cubic foot. The Resistance of 1 mil.
foot at 60 deg. Fahr. is, according to Dr. Matthiessen, 10.32311 ohms. Upon
these data the above Table has been calculated.

The _Resistance_ of Copper varies with the temperature about 0.38 per
cent. per degree Centigrade, or 0.21 per cent. per degree Fahrenheit.

STRANDED WIRES.--With a conductor of a definite lenght, made of
_Stranded_ Wires, the total _weight_ is _greater_, and the _Resistance
less_ than is a similar length of Conductor with Wires _not_ Stranded.

To convert--Inches to Millimetres multiply by 25.3994
Feet to Metres " .3048
Yards to Metres " .9144
Miles to Kilometres " .6214
Pounds to Kilogrammes " .45359

PEPARED BY WALTER T. GLOVER & CO., ELECTRICAL WIRE AND CABLE MAKERS, 25,
BOOTH STREET MANCHESTER.

* * * * *

IRON FRAME GANG MILLS.

The gang mill is regarded as possessing material advantages in the rapid
and economical manufacture of lumber. Among the recent improvements
tending to perfect such mills, those which are shown in the iron frame
stock gang, manufactured by Wickes Bros., East Saginaw, Mich., are
eminently valuable. Our large engraving represents one of these mills,
constructed to be driven by belt, friction, or direct engine, as may be
desired. The important requisite in this class of mills is such design
and proportion of parts as will insure durability and continued movement
at the highest speed, safely increasing the quantity and improving the
quality of work done at a lesser feed, and admitting the use of thinner
saws than is practical in the slower moving sash. These are among the
advantages gained in the iron frame machine, overcoming the necessity
of an expensive mill frame, saving time and expense in setting up, and
avoiding the liability of decay or change of position.

[Illustration: IMPROVED IRON FRAME GANG SAW MILL.]

Many improvements have been made in the mechanism of oscillation, and
from these the builders of this mill have adopted what is known as the
Wilkin movement, which oscillates the top and bottom slides. The top
slides are pivoted at the top end, and the bottom ones from the bottom
end, both being operated by one rock shaft from the center. This
movement when properly adjusted gives an easy clearance and the easiest
cut yet obtained. It adds no extra weight to the sash, and avoids the
cumbrous rock shaft and its attendant joints, usually weighing from
three hundred to five hundred pounds, which have been found so
objectionable in many other movements. The feed is continuous, and is
made variable from 1/4 to 11/4 inch to each stroke, controllable by the
sawyer. Power is applied to the press rolls in the double screw form
with pivot point, also operated by the same hand. A special feature of
this machine is the spreading of the lower frame so that its base rests
upon an independent portion of the foundation from the main pillow block
or crank shaft. The solidity of the whole structure is thus increased,
both by the increased width at the base and the prevention of connecting
vibrations, which necessarily communicate when resting upon the same
part, as in other forms of such machines heretofore in use.

The mill shown in the perspective view is one of twenty-six saws 41/2 feet
long, sash 38 inches wide in the clear, and stroke 20 inches, capable
of making 230 strokes per minute. The crank shaft is nine inches in
diameter, of the best forged iron. The main pillow block has a base
61/2 feet long by 21 inches bearing, weighing 2,800 pounds. The cap
is secured by two forged bolts 31/2 inches in diameter, and by this
arrangement no unequal strain upon the cap is possible. A disk crank is
used with suitable counterbalance, expressly adapted to the weight and
speed of sash; a hammered steel wrist pin five inches in diameter, and a
forged pitman of the most approved pattern, with best composition boxes.
The iron drive pulley is 4 to 41/2 feet in diameter and 24 inches face;
the fly-wheel six feet in diameter, and weighing 4,700 pounds, turned
off at rim. When a wider and heavier sash is required, a proportionate
increase is made in all these parts.

In the construction of the sash the stiles are made of steel; the lower
girt and upper heads are made in one solid piece, without rivets, giving
the greatest strength possible, with the least weight. The outfit also
includes eight iron rollers for the floor, 81/2 inches in diameter, with
iron stands, and geared as live rolls when desired, a full set of
Lippencott's steel saw hangings, and gauges for one-inch lumber. The
weight of the machine here shown is 181/2 tons. They are, however, built
in larger or smaller sizes, adapted to any locality, quality or quantity
of work desired.

* * * * *

It is said that the St. Gothard Tunnel is diverting the bulk of the
Italian trade into the hands of the Belgians, Germans, and Hollanders
with startling rapidity. Without breaking bulk, early fruits are taken
from all parts of Italy to Ostend, Antwerp, and Rotterdam, whence they
are carried by fast steamers to London and other English ports. But, on
the other hand, Germany is sending into Italy large quantities of coal,
iron, machinery, copper, and other articles of which the latter received
nothing before. In two months alone, the Italians imported 1,446 tons of
paper.

* * * * *

THE HEAT REGENERATIVE SYSTEM OF FIRING GAS RETORTS.

The system of heat regeneration in the firing of gas retorts, in
accordance with the principle which Dr. C.W. Siemens has worked out in
such a variety of ways in the industrial arts, has lately been applied
with very marked success at the Dalmarnock Station of the Glasgow
Corporation Gas Works. Notwithstanding the fact that a period of about
twenty years has elapsed since Dr. Siemens successfully adapted his
system to the firing of retorts at the Paris Gas Works, it seems to have
made but little progress up to the present time; for what reasons it is
perhaps difficult to explain. It is certain, however, that so-called
regenerator furnaces of various forms have, from time to time, been
brought into use at gas works for the purpose in question both on the
Continent and in this country; and in recent years the subject has
received much attention from gas engineers, the general opinion
eventually being that the adoption of such a system of working would be
certain to result in so great an amount of economy as to put gas as an
illuminating agent on a more secure footing to compete successfully with
its modern and somewhat aggressive rival, the electric light. Of course,
it is now admitted that the mode of adapting the heat regenerative
principle at the Paris Gas Works was attended with a degree of
complexity in the structural arrangements that was so great and so
expensive as to place it practically beyond the reach of gas companies
and gas corporations generally, when the expense as well as the
scientific beauty and practical efficiency of the new mode of applying
and utilizing heat had to be considered. Fortunately, however, Dr.
Siemens was enabled two or three years ago to demonstrate that there was
no such thing as "finality" in that department of invention which he had
made almost exclusively his own. About the time mentioned he placed
his most advanced views on gas producers and on the regeneration and
utilization of heat before the world, and within that period a most
decided step in advance has been made, the structural arrangements
now required for gas producers and regenerator furnaces having been
immensely simplified and cheapened, while their practical utility has in
no way been interfered with.

Scarcely had Dr. Siemens announced his new form of gas producer and
regenerator than communication was opened with him by Mr. W. Foulis, the
general manager to the Glasgow Corporation Gas Trust, with the view of
entering into arrangements for its adoption on an experimental scale
at one of the stations under his charge. Encouraged by the hearty
co-operation of the gas committee, two or three of whose members were
well known engineers, Mr. Foulis very soon came to an understanding with
Dr. Siemens to have the regenerative system put to a thorough test at
the Dalmarnock Gas Works, situated in the extreme east end of the city,
and the largest establishment of the kind in Scotland, the total number
of retorts erected being about 750. The system in its most recent shape
was applied to four ovens, each of which had seven retorts, but which
number has since been increased to eight, owing to the space occupied
by the furnace in the ordinary settings being rendered available for
an additional retort in the new or "Siemens" setting. For each oven or
chamber of eight retorts there was erected a separate gas-producer,
so that even one set of eight retorts might alone be used if thought
necessary.

[Illustration: GAS RETORTS WITH REGENERATIVE FURNACES .--GLASGOW
CORPORATION GAS WORKS.]

In Figs. 1 and 2 of our illustrations, the general arrangement and the
relationship of the gas producer, the regenerators, and the retorts to
each other are clearly shown. It was a sort of _sine qua non_ of the new
method of firing the retorts that the producer should be in as close
proximity as possible to the place where the gaseous fuel was to be
used, and it was concluded that the most convenient situation would be
immediately in front of its own set of eight retorts, and with its top
on a level with the working floor of the retort house. To place it
in such a position meant a good deal of excavation, which was also
required, however, for the regenerator flues. The excavation was carried
down to a depth of 10 ft. below the level of the retort house floor, and
as a matter of course the operation of underpinning had to be resorted
to for the purpose of carrying down the foundations of the division
walls, which, together with the main arches and the hydraulic main, were
in no way otherwise disturbed. As in most new inventions, a good deal
of difficulty was experienced at first in connection with these gas
producers and heat regenerator furnaces; but by dint of application and
by the adoption of modifications made here and there in the arrangements
from time to time, as also by a determination not to be beaten, although
often disheartened, Mr. Foulis was ultimately rewarded with complete
success. The new system of firing being made so simple that there was
scarcely any possibility of failure likely to arise in ordinary practice
if it was superintended with but a moderate amount of care.

[Illustration: _Fig. 3._]

The results which were obtained in course of time with four ovens, or a
total of 32 retorts, were so exceedingly promising that it was forthwith
resolved to extend the new mode of firing to the whole of a double bench
of twelve ovens, now containing 96 retorts; and all the improvements
which had suggested themselves during the working experiments with the
four ovens were adopted from the first in the reconstruction of the
remaining eight ovens in the bench. More recently the regenerator system
has been applied to other 22 ovens, or 176 additional retorts, being the
whole of one of the main divisions of the retort house; and during the
very depth of the present winter, when the demand for gas was at its
greatest height, all the retorts of the converted or "Siemens" settings,
amounting to 272, were in full working activity, in which condition they
still remain. It is intended to make another very considerable extension
of the heat regenerative system of firing during the ensuing spring and
summer. The reconstruction of the present year will extend to the ovens
of seven retorts each, giving in this case eighty gas fired retorts; and
to twenty ovens of five retorts each, which will become sixteen ovens,
each having eight retorts, making 128 retorts in this division, and the
total being 208 retorts in place of 170 in the same amount of space. It
is confidently anticipated, therefore, that by the month of August of
the present year, 480 full sized retorts will be available for working
out the new method at the Dalmarnock Gas Works. Furthermore, the
confidence which has been inspired in the minds of the members of the
Glasgow Corporation Gas Committee and their engineer regarding the
actualities and possibilities of the Siemens system of firing gas
retorts, in its most improved state, is such that arrangements are
being made for starting shortly to apply it throughout at the Dawsholm
Station, which is situated in the suburban burgh of Maryhill, and some
four or five miles distant from the Dalmarnock Works in a northwestern
direction. The station just named, which is also a very large one, will
probably require two years for its conversion.

We shall now give some account of the structural arrangements adopted
for producing cheap gaseous fuel, and for turning that fuel to the
greatest advantage in firing the retorts for the purpose of carbonizing
the cannel coal used as the source of the gas.

The gas producer, which is represented in vertical section in Fig. 2, is
a cylinder of brickwork inclosed in a casing of malleable iron. It is 7
ft. 6 in. deep, and 3 ft. in diameter, which becomes reduced to 20
in. above, where it is closed by means of a cast-iron lid, which is
continuous with the floor of the retort house. There are no firebars
at the bottom, so that the fuel rests on a floor of firebrick. At the
bottom of the walls of the producer there are several holes about 1 ft.
in length by 6 in. in height. By means of these openings any clinker
that may form and the ashes of the spent fuel can readily be withdrawn.
They also allow of the admission of air to maintain the combustion in
the lower portion of the mass of fuel; and at each opening there is a
malleable iron tube for delivering a jet of steam direct from a steam
boiler. We shall subsequently explain the functions performed by the
steam.

The fuel employed is the coke or char resulting from cannel coal when it
has yielded up its hydrocarbons and other gases during the process of
carbonization in the gas retorts. Being entirely made from Scotch cannel
the coke is very poor in quality, as it contains a large percentage of
mineral matter or ash relatively to its fixed carbon. The retorts are
worked with three-hour charges, but the producer is only charged once in
every six hours For each set of eight retorts the charge of raw cannel
is about 18 cwt., and it is found in practice that the coke drawn from
five of the retorts is quite sufficient to fill up the producer to the
top. Formerly a set of seven retorts fired in the ordinary way from a
furnace underneath, required from 60 to 75 per cent. of the coke made,
but now, with eight retorts in each oven, the quantity has been reduced
to about 30 per cent., or less than one-half of what it formerly was.
Before the retorts are drawn the lid is removed from the top of the
producer, and any fuel still remaining unconsumed is touched up a bit by
way of leveling it on the surface, and as soon as it has been filled up
to the constricted portion a shovelful of soft luting is spread over the
top of the coke, and the lid is laid upon it and driven home, thereby
making a perfectly air-tight joint. The contents of the other three
retorts, as also the contents of the whole of the retorts at each
alternate drawing, are taken to the coke heap in the yard. We have
already spoken of a charge of cannel as being about 18 cwt. for each set
of eight retorts, but in connection with that matter we should mention
that it was formerly about 13 cwt. per oven containing seven retorts,
and that there is every prospect of it being increased without
increasing the length of time occupied in carbonizing the cannel of each
charge.

It may be worth while now to notice briefly what takes place among the
mass of coke in the gas producer. The atmospheric air admitted at the
several openings previously spoken of ascends through the lower layers
of the incandescent coke, the carbon of which burns to carbonic acid
gas at the expense of the oxygen of the air. Among the middle and upper
layers of the incandescent coke the carbonic acid gas takes up a further
quantity of the fixed carbon, and becomes transformed into carbonic
oxide gas (CO_{2}+C=2CO), which is an inflammable body, and possesses
considerable calorific power. Unless the carbonic acid gas is very
completely "baffled" in its ascent through the coke in the producer, a
quantity of it passes into the furnace along with the carbonic oxide,
the efficiency of which is diminished in proportion as the former
increases in quantity. Of course, also, the nitrogen associated with
the oxygen in the air admitted to the gas generator passes on with the
carbonic oxide gas, this nitrogen acting as a dilutant and being of
course absolutely useless as a generator of heat. The steam which
we previously spoke of serves two good purposes. In contact with
incandescent coke it suffers decomposition, its oxygen uniting with some
of the fixed carbon to form carbonic oxide, while the hydrogen which
is set free passes onward, and mixes with the other gases to be
subsequently consumed with them. The admission of the steam thus causes
the absorption of heat in the gas generator where the decomposition
takes place, this heat being again evolved on the subsequent combustion
of the hydrogen. Then, again, as the steam is delivered in among the
coke in a jet, or a series of jets, it has the effect of almost entirely
preventing any clinkering or slagging of the earthy and silicious
materials, which form such a large portion of the substance of the coke
obtained from Scotch cannels, sometimes as much as from 15 to 20 per
cent. It is scarcely necessary for the stokers to go down below to the
bottom of the producers to remove the ash above once in every six hours.
Referring to the composition of the gaseous fuel obtained from cannel
coke in one of these gas producers, we give the following typical
analysis on the authority of Dr. William Wallace, F.R.S.E., gas
examiner, and one of the public analysts for the city of Glasgow:

Per cent.
Hydrogen 8.7
Carbonic oxide 28.1
Carbonic acid 3.5
Oxygen 0.4
Nitrogen 59.3
-----
100.0

By again referring to Fig. 2, it will be observed that an opening is
provided for the passage of the gaseous matter as it is formed into the
mass of brickwork, the upper half of which is occupied by the retorts of
the setting and the lower by the regenerators.

Before following the gas we may first direct attention to the
arrangements for dealing with it, and with the air that has to be
admitted for the combustion of so much of it as is of a combustible
nature. It will be seen by reference to Fig. 1 that the oven proper is
occupied by eight [Inline Illustration] shaped retorts. These are 9 ft.
long (set back to back) by 18 in. by 13 in., and they are placed on
arches which are 8 ft. 6 in. wide. Underneath the level of the retort
oven there are two regenerators or regenerator chambers, which differ
very materially in form from the regenerators formerly applied by Dr.
Siemens to gas retort ovens, and which are still employed for high
temperature furnaces like those used for steel and glass melting. In
the case of these latter the regenerators are on the alternating
system--that is to say, a mass of brickwork is heated by the waste heat
of the effluent gases, and when that is made sufficiently hot, the
current of waste gases is turned into a second mass of brickwork, while
air is admitted to pass through the brickwork already heated. The system
thus briefly described entails a certain amount of attention on the part
of the workmen in the altering of the valves or dampers to reverse the
currents. The regenerator now adopted consists of an arrangement of six
zigzag flues, three on each side of the setting. These flues run the
whole length of the setting. As indicated by the arrows pointing
downward in Fig. 3, the waste gases on their way to the chimney stack
pass to and fro through the side flues, thus giving up a large portion
of their contained heat by the process of conduction or contact to the
central flue through which the incoming air passes. The air necessary
for combustion is first admitted into a large chamber in the center, and
then it is divided into two currents, which pass right and left into the
central passages of the two regenerators. As the air flue is at a very
bright heat for a considerable distance before the air leaves it, the
temperature of the air must be equally great, or nearly so. In its most
improved form one of these heat regenerative furnaces provides an amount
of heating surface extending to 234 square ft., which is exposed to the
air on its way to the combustion chamber.

Passing from the producer through the flue provided for it, the gas
enters the retort setting underneath the side retorts, where it meets
the air coming from the regenerator. It enters the setting, not by a
number of small openings, but by one large opening on each side, and
meets the air entering also by a large opening, the effect of which is
to avoid the localization of intense heat, as all the retorts of the
setting become enveloped in an intensely heating flame, due to the
combustion of the carbonic oxide and hydrogen gases.

There are various advantages attending this system of firing gas
retorts. First of all, there is already a saving of fuel to the extent
of one-half, and not unlikely there will soon be a further very decided
increase in the saving of fuel to record, inasmuch as it has been
experimentally determined within the past two or three weeks that, by
increasing its diameter to 3 ft. 4 in., one producer can be made to
provide a sufficient amount of gaseous fuel to fire two sets of eight
retorts. By the arrangement just hinted at the relative amount of fuel
used will be still further reduced. Then, again, an additional retort
can well be placed in each oven, as it occupies the position of the fire
in ordinary settings. In the third place, by the greater heat which is
obtained, the charges can be more rapidly distilled; or heavier charges
can be carbonized in a given space of time. When all the gains are put
together, the amount of coal carbonized is increased by about 40 per
cent. over any specified time. Of course, in the new or regenerator
settings there is much greater regularity of heat; and as the gaseous
fuel is perfectly free from all solid matter, and burns without any
trace of smoke, there is a total absence of deposit on the outside of
the retorts. From these two circumstances combined it is but natural to
expect that there should be greater durability of the retorts--which
is really the case. Another advantage is that, as the fuel used in
the furnaces is wholly gaseous, choking of the flues cannot by any
possibility arise. It is the confident opinion of Mr. Foulis that the
system in question can be applied with advantage to all sizes of gas
works, and that it is certainly well adapted for all works where the
summer consumption of gas is sufficiently large to give employment to
eight retorts.

As this is the first instance of the new form of gas producer and
regenerator having been adopted in any gas works, a very great amount
of scientific and practical interest attaches to it. Many persons have
visited the Dalmarnock Gas Works during their reconstruction, in order
to see the system in operation, and doubtless many more will go and do
likewise when they learn of the numerous advantages which it possesses,
and which are likely to increase rather than diminish.--_Engineering_.

* * * * *

A NEW GAS-HEATED BAKER'S OVEN.

During the past few weeks, a highly interesting experiment--and one,
moreover, destined to materially influence the development of the uses
of gas in a fresh field--has been in progress, under the guidance of Mr.
Booer, at a baker's shop in the Blackfriars Road, London. The experiment
in question is nothing less than the application of gas for heating
bakers' ovens, in a manner not hitherto attempted, and such as to bring
the system within the means of the poorest tradesman in all but the
smallest towns. It will be remembered that the success of the gas-heated
muffles for burning tiles and glass led to the attempted construction of
a model baker's oven, heated by the same fuel, which was shown in action
at the Smoke Abatement Exhibition at South Kensington in the winter
of 1881-82. This model attained considerable success; but its design
demanded either a new structure in every case, or considerable
alteration of any existing oven. In the proposed system, moreover,
the oven was heated wholly from without--a condition supposed to be
necessary to meet the objections of the bakers. It is evident, however,
that there must be considerable waste of gas in heating a mass of tiles
and brickwork, such as go to the construction of a common baker's oven,
from the outside; and the objection to handicapping such a costly fuel
as gas in this manner becomes more apparent when it is remembered that
in the usual way the oven is always heated by an internal coal fire.
When it is further considered that the coal commonly used by bakers is
of the most ordinary quality, full of dirt that would condemn it in the
estimation of a gas manager, the sentimental objection to allowing a
purified gas flame to burn in a place which this rubbish is permitted to
fill with foul smoke becomes supremely ridiculous. Consequently, when
Mr. Booer, whose work in connection with the gas muffle is well known
in England and America, seriously addressed himself to construct, upon
altogether new lines, a cheap and practical baker's oven, he wisely put
the gas inside.

There are many other conditions which Mr. Booer, after consultation with
practical bakers and others, set himself to fulfill, the observance
of which lends to the present Blackfriars experiment much of its
interesting character. Thus it was observed that, while it is not
difficult to build an oven in a given spot, and bake bread in it, this
cannot truly be called a _baker's_ oven. By this term must be understood
in particular an oven in an ordinary bakehouse, set in the usual style
and worked by a man with his living to get by it. Before the problem of
extending gas to bakers' ovens could be considered solved, it had to be
attacked from this aspect. Mr. Booer, to do him full credit, seems to
have early appreciated this fact in all its bearings. He not only saw
that it was necessary to save gas, as much as possible, by putting it
inside the oven; but he was told that, in order to meet with any general
success, the cost of converting an oven to the gas system must be
rigidly kept down to about ten or twelve guineas. The latter seems
a particularly hard condition, when it is remembered that the only
improved baker's oven in practical use at the present day is the steam
oven invented by Mr. Perkins, which costs two or three hundred pounds to
erect. Mr. Booer also had in mind the necessity that everything possible
for a coal oven must likewise be performed by a gas oven; and in this
respect he set himself to surpass the costly Perkins oven, which will
not bake the common "batch" or household bread, generally the principal
article of sale, more especially in populous and poor neighborhoods. The
peculiar efficacy of the common coal fire in this respect proceeds from
the essential principle of action of a brick oven, which is found simply
in the fact that the work is done entirely by heat previously imparted
to the tile bottom, roof, and sides of the oven, and thence radiated to
the bread. No other kind of heat will bake batch-bread--i.e., loaves
packed in contact with one another--which requires to be thoroughly
soaked by a radiant heat in a close atmosphere of its own steam. Now,
as a coal fire is eminently qualified to impart, by radiation and
otherwise, this necessary store of heat to the brickwork, it is plainly
a difficulty to effect the same purpose with a fuel which, of
itself, can scarcely radiate heat at all. The system of the gas
cooking-oven--the utilization of the heat of the combustion products as
formed--is clearly inapplicable here; for a different kind of heat is
needed, under conditions that would not sustain continuous combustion.
Therefore, there is nothing for it but to heat the bottom and sides
of the brick oven by the direct contact of powerful gas-flames; thus
supplanting the coal fire, but leaving the actual work of baking to be
done afterward by stored-up heat in the regular way.

Having settled the general principles of a system of this kind, there
still remain a number of scarcely less important details, in the dealing
with which lies the difference between practical success and failure.
Thus it is not merely sufficient to heat an oven for bread baking; it is
also necessary to heat it within the times and according to the habits
of work to which the baker has been accustomed. Work in town bakeries
begins at about midnight, or shortly after, and the condition of the
oven must conform to the requirements of the dough, which vary from day
to day and from season to season. In order to master all these niceties,
as far as a knowledge of them is necessary to his purpose, Mr. Booer
has spent many nights in the bakehouse in the Blackfriars Road; and has
thereby obtained a command over the technicalities of the work which has
served him in good stead, not merely for adjusting his gas heat, but in
answering the innumerable objections always raised when a revolution in
an immemorial trade is threatened. It is with considerable satisfaction
that we are enabled to declare, after duly weighing all the conditions
as to first cost and otherwise imposed by himself and others, that Mr.
Booer has succeeded, upon these terms, in vindicating the claims of gas
to be a cheap, efficient, and cleanly fuel for heating ovens under the
control and according to the methods of working of the baker himself.

The oven with which this success has been achieved is one of two in the
bakehouse of Mr. Loeber, of 161 Blackfriars Road. It measures 7 feet by
6 feet internally; being what is technically termed a 6 bushel oven. The
alterations made by Mr. Booer consist in the first place in the removal
of the flooring tiles, and the laying down of a new bottom, under which
run a number of flues radiating from the side furnace. The throat of the
furnace, where it enters the angle of the oven, is bricked up, and eight
pieces of 3/4-inch gun-barrel tubing project above this dwarf wall,
and radiate fan-shaped under the dome of the roof. These are the
gas-burners, which are supplied from a 11/2-inch pipe led into the old
furnace. The same pipe supplies the similar burners which are inserted
in the flues under the oven bottom. This is really all the plant
required. It should be remarked that these bottom flues are carried to
different points of the side walls, and the products of combustion are
allowed to rise upward into the oven through gaps left for the purpose.
A supplementary supply of heated air is provided to help the combustion
of the gas in these flues, which would otherwise be languid. When the
gas is turned on from the main cock in the furnace either to the top or
the bottom set of burners, a long match is used to light them from
the same point. This is effected without risk of firing back, by the
adoption of a specially constructed atmospheric nipple and shield, the
pattern of which is registered. The flame from the top burners unites in
a sheet of fire, which spreads out all over the crown of the oven, at
the same time that the burners below are doing their work, and the
products of combustion flow together through the oven to the chimney,
which is the same that was used for coal. At first, as might be
expected, there was considerable difficulty in finding the most suitable
position of the chimney damper, aggravated in this case by the fact that
the other oven worked with a coal fire into the same shaft. Finally,
however, the two flues were disconnected with the happiest results.
During the past fortnight the oven has been in regular use, and the
bread has been sold over the counter in the ordinary course of trade.
Two and three batches of bread have been baked in one day in this oven;
the economy of its use, of course, increasing with the number of loaves
turned out. As a rule the gas is lighted for about an hour before the
oven is wanted, and about 250 cubic feet are used. Then the cocks are
shut and the oven is allowed to stand closed up for ten minutes, in
which time it ventilates itself, and the heat spreads over it. Then the
batch is set, and the baking occupies from an hour to an hour and a
half, according to the different classes of loaves. Two batches are
baked with a consumption of about 620 cubic feet of gas; costing, at 2s.
10d. per 1000 cubic feet, just 11d. each batch for fuel. This cannot be
considered costly. But the system possesses many other advantages. In
the first place, it is much more cleanly than coal; for the oven never
requires wiping out, which is usually done with a bundle of old rope
called a "scuffle" and the operation is attended with a most unpleasant
odor. Then there is no smoke--a great advantage from the point of
view of the Smoke Abatement Institution. More to the purpose of the
journeyman baker, however, is the fact that there is no stoking to be
done, and he can therefore take his repose at night without having to
attend to the furnace. Besides this the master has the satisfaction of
knowing that the oven will always be hot enough if he simply attends to
the time of lighting the gas--a consideration of no small moment. It is
no mean testimony to the reality of Mr. Booer's success that Mr. Loeber,
having seen his difficulties and troubles from the beginning, and marked
how they have been overcome, is content to acknowledge that even this
first example is capable of turning out bread in a condition to be sold
over the counter. There is a good opening in this direction, for there
are 6,000 bakeries in London alone, to every one of which Mr. Booer's
system might be applied with advantage to the tradesman and his
customers. And what may be done with gas at about 3s. per 1,000 cubic
feet may certainly be done to still greater advantage in many towns
where the price is lower. Mr. Booer has entered upon his work in a
proper spirit. He has begun at the beginning, with the necessities of
the baker; and has gone plodding on quietly, until he has achieved a
noteworthy success. It may be hoped he will receive the reward which his
perseverance merits.--_Jour. of Gas Lighting_.

* * * * *

CAPTAIN MATTHEW WEBB.

Who was drowned on July 24 in attempting to swim through the whirlpool
and rapids at the foot of the Falls of Niagara, was born at Irongate,
near Dawley, in Shropshire, January 18, 1848. He was 5 feet 8 inches in
height, measured 43 inches round the chest, and weighed about 141/2 stone.
He learnt to swim when about seven years old, and was trained as a
sailor on board the Conway training-ship in the Mersey, where he saved
the life of a fellow seaman. In 1870 he dived under his ship in the Suez
Canal and cleared a foul hawser; and, on April 23, 1873, when serving on
board the Cunard steamer Russia, he jumped overboard to save the life of
a hand who had fallen from aloft, but failed, and it was an hour before
he was picked up almost exhausted. For this he received a gold and
other medals. He became captain of a merchant ship, but soon after he
relinquished the sea and devoted himself to the sport of swimming.

At long distance swimming in salt water he was _facile princeps_, but he
did not show to such advantage in fresh water. In June, 1874, he swam
from Dover to the North-East Varne Buoy, a distance of 11 statute miles.
On July 3, 1875, he swam from Blackwall Pier to Gravesend Town Pier,
nearly 18 statute miles, in 4 hours 52 minutes. On the 19th of the same
month he swam from Dover to Ramsgate, 191/4 statute miles, in 8 hours 45
minutes. On August 12, 1875, he tried to cross from England to France,
and although he failed, owing to the heavy sea, he compassed the
distance from Dover to the South Sand Head, 151/2 statute miles, in 6
hours 48 minutes. On the 24th of the same month he made another attempt,
which rendered his name famous all over the English-speaking world.
Starting from Dover, he reached the French coast at Calais, after being
immersed in the water for 21 hours 44 minutes. He had swum over 39
miles, or, according to another calculation, 451/2 miles, without having
touched a boat or artificial support of any kind. Subsequently he swam
at the Lambeth Baths, and the Westminster Aquarium, and last year, at
Boston, U.S., he remained in a tank nearly 1281/2 hours. Latterly he had
suffered from congestion of the lungs, and his health had become much
impaired.

[Illustration: CAPT. MATTHEW WEBB.]

The story of his final and fatal effort needs here but a brief
description. At two minutes past four, on July 24, Webb dived from the
boat opposite the Maid of the Mist landing, and, amid the shouts and
applause of the crowd, struck the water. He swam leisurely down the
river, but made good progress. He passed along the rapids at a great
pace, and six minutes after making the first plunge passed under the
Suspension Bridge. Immediately below the bridge the river becomes
exceedingly violent, and as the water was clear every movement of Webb
could be seen. At one moment he was lifted high on the crest of a wave,
and the next he sank into the awful hollow created. As the river became
narrower, and still more impetuous, Webb would sometimes be struck by a
wave, and for a few moments would sink out of sight. He, however, rose
to the surface without apparent effort. But his speed momentarily
increased, and he was hurried along at a frightful pace. At length he
was swept into the neck of the whirlpool. Rising on the crest of the
highest wave, he lifted his hands once, and then was precipitated into
the yawning gulf. For one moment his head appeared above the angry
waters, but he was motionless, and evidently at the mercy of the waves.
He was again drawn under the water, and was seen no more alive. Some
days later his body was found four miles below the fatal Rapids. It bore
tokens of the fearful violence of the struggle which he had undergone.
His bathing drawers were torn to fragments, and there was a deep wound
in his head. An inquest was held, and the jury returned a verdict of
"Found drowned."

Captain Webb was married about three years ago, and leaves a widow and
two children. It is understood that he risked his life in this last
fatal attempt to obtain money for the support of his family.--_London
Graphic_.

* * * * *

SEMI-DETACHED VILLAS, BROMFIELD CRESCENT, HEADINGLEY.

These houses are situated in a pleasant part of Headingley, which is
the favorite residential suburb in the locality of Leeds. As regards
accommodation, the ground-floor of each house comprises good-sized
drawing and dining rooms, each with bay windows; well-lighted entrance
halls, opening upon wooden verandas; kitchen, pantry, and scullery; on
first floor are three good bedrooms, a bathroom, and other necessary
accommodation; on second floor are two additional bedrooms. The basement
contains coal-place and larder.

In these houses an attempt has been made to produce conveniently-planned
and well-arranged habitations, combined with a pleasing and picturesque
exterior, without involving a large outlay of money. The materials used
are brick of a deep red color for facings, red terra-cotta from Messrs.
Wilcock & Co., of Burmantofts, for moulded strings, sills, etc., and a
very sparing use of stone from the Harehills Quarries. The front gables
are constructed of timber in solid scantlings, well framed, and pinned
together with oak pegs, filled in and well backed behind with brickwork;
the panels faced with cement, which, together with the cored cornice,
are finished in vellum color. The whole of the woodwork of exterior is
painted a neutral shade of peacock blue, forming an admirable contrast
with the deep red of the bricks, the sashes and casements only being
finished in cream color. The whole of the chimneypieces in the interior
are carried out from the architect's special design; those in the
drawing-rooms being of mahogany, finished in rosewood color, and those
in dining-rooms of oak, stained with ammonia and dull wax polished.

[Illustration: SUGGESTIONS IN ARCHITECTURE.--SEMI-DETACHED VILLAS,
BROMFIELD CRESCENT, HEADINGLEY, LEEDS.]

The houses, with outbuildings and boundary walls, which have been
erected for Mr. John Hall Thorp, of Bromfield, Headingley, have cost
L1,450, or thereabouts, this amount not including the price of
land. They have been carried out from the designs and under the
superintendence of Mr. William H. Thorp, A.R.I.B.A., architect, of St.
Andrew's Chambers, Park Row, Leeds.--_The Architect_.

* * * * *

THE DWELLINGS OF THE POOR IN PARIS.

In view of the possible approach of cholera, and the sanitary
precautions that even the most neglectful of authorities are constrained
to take, it is of some interest to us, says the _Building News_, to know
how the poor are housed in the city of Paris, which contains, more than
any city in the world, the opposite poles of luxurious magnificence
and of sordid, bestial poverty. The statistics of the Parisian working
classes in the way of lodgings are not of an encouraging nature, and
reflect great discredit on the powers that be, who can be stern enough
in the case of any political question, but are blind to the spectacle
of fellow creatures living the life of beasts under their very eyes. In
1880, the Prefect of Police gave licenses to 21,219 arrivals in the city
of French origin, and to 7,344 foreigners. In the succeeding year,
the former had increased to 22,061, while the latter had somewhat
diminished, being only 5,493. There was a census taken in 1881, from
which it appeared that Paris contained 677,253 operatives and 255,604
employes and clerks, while out of every 1,000 inhabitants, 322 only
were born in the city, and 565 came from the departments or the French
colonies. The foreign element in the working classes has increased
very rapidly, numbering 119,349 in 1876, to which by 1881 there was an
addition of 44,689. To every 1,000 inhabitants, Paris now numbers 75
foreigners, though in 1876 the proportion was only 60. It may not be
amiss to state that the annual increase of the Paris population is at
the rate of 56,043 persons, and that in the five years 1876-81, the city
received 280,217 additional mouths. The total population of the capital
is 2,239,928, of whom 1,113,326 are males.

Returning to the poorer classes, we find that in 1872 they were
estimated at 100,000; but that in 1873 they had risen to 113,733, and
in 1880 to 123,735. It is unfortunate to be obliged to say that the
majority of these people are housed worse in Paris than in almost any
other great city in the world. There are two classes of lodgings for the
poor--the one where the workman rents one or more rooms for his family,
and, perhaps, owns a little furniture; the other, a single room tenanted
for the night only by the unmarried man who pays for his bed in the
morning and gets his meals anywhere that he can. Readers will remember
how, under the auspices of M. Haussmann, western Paris was almost pulled
down and transformed into a series of palatial boulevards and avenues.
While the work lasted the Paris workman was well pleased; but he did
not like it quite so much when the demon of restoration and renovation
invaded his own quarters, such as the Butte des Moulins, and all that
densely populated district through which the splendid Avenue de l'Opera
now runs. The effect of all this was to drive the workman into the
already crowded quarters at the barriers, such as La Gare, St. Lambert,
Javel, and Charonne, where, according to the last statistics of the
_Annuaire_, the increase was at the rate of 415 per 1,000. Of course the
ill health that always pervaded these quarters increased also; and, from
the reports of Dr. Brouardel and M. Muller, the number of deaths from
typhoid and diphtheria were doubled in ten years. Dr. Du Mesnil, in
making his returns for 1881 of convalescents from typhoid, remarked that
the most unsanitary arrondissements were the 4th, 11th, 15th, 18th, and
19th--precisely those to which the principal migrations of laborers had
taken place. The 18th arrondissement, which in 1876 had only 601 lodging
houses with 8,933 lodgers, had, in 1882, over 850, with 20,816 inmates.
In the 19th arrondissement there were 517 houses in 1876, with 9,074
lodgers, and 752 in 1882, with 17,662 inhabitants.

It is not only the crowded condition of the poor quarters that is such a
standing menace to the health of the city, but also the shocking state
of the rooms, which the unhappy lodgers are obliged to put up with. The
owners of the property are, as happens in other places besides Paris,
unscrupulous and grasping to the last degree, and have not only divided
and subdivided the accommodation wherever possible, but have even raised
the rental in nearly all cases. Whole families are crowded into a small
apartment, icy cold in winter, an oven in summer, the only air and
daylight which reaches the interior coming from a window which looks on
to a dirty staircase or a still fouler court reeking with sewage. There
are at the present time in Paris 3,000 lodgings which have neither stove
nor chimney; over 5,000 lighted only by a skylight; while in 4,282 rooms
there are four children in each below 14 years of age; 7,199 with three
children; and 1,049 with four beds in each. The Parisian population has
augmented only 15 per cent. in seven years; but the district of poor
lodging houses has increased by twenty per cent., and the number of
lodgings by about 80 per cent. It is true that a law was passed in 1850
to provide for the sanitary supervision of this class of property; but
in Paris the law is a dead letter, and, although it is now active in the
provinces and in places like Marseilles, Lyons, Bordeaux, and Nantes, it
is applied, even there, in a jerky and intermittent manner.

Perhaps the worst of the abominable dogkennels called houses was the
group known as the Cite des Kroumirs, in the 13th arrondissement, which,
by a strange irony, was built on land belonging to the Department of
Public Assistance, which was let out by that body to a rich tenant, who
sublet it to these lodging-house owners. This veritable den of infection
and misery has now been demolished; but there are plenty of others quite
as bad. Notably, there is the Cite Jeanne d'Arc (a poor compliment to
have named it after that sturdy heroine), an enormous barrack of five
stories, which contains 1,200 lodgings and 2,486 lodgers. No wonder that
it was decimated in 1879 by smallpox, which committed terrible ravages
here. The Cite Dore is grimly known by the poor-law doctors as the
"Cemetery Gateway." The Cite Gard, in the Rue de Meaux, is inhabited
by 1,700 lodgers, although it is almost in ruins. The Cite Philippe is
tenanted by 70 chiffonniers, and anybody who knows what are the contents
of the chiffonnier's basket, or _hotte_, may easily guess at the
effluvia of that particular group of houses. A large lodging-house in
the Rue des Boulangers is tenanted by 210 Italians, who get their living
as models or itinerant musicians. Both house and tenants are declared to
be unapproachable from the vermin.

It is some satisfaction to know that these houses have lately awakened
the apathy of some of the public bodies, and that more than one
scheme is being put forward with a view of erecting proper industrial
dwellings. The Municipal Council is negotiating with the Credit Foncier
for the erection of a certain number of cheap houses, which, for the
space of twenty years, will be exempt from all taxes, such as
octroi, highway, door and window tax, etc. There are also one or
two semi-private companies, which are occupying themselves with the
question, and it is to be hoped that the rumors of the pestilence in
Egypt may hasten the much-needed reform.

* * * * *

There can be no doubt, says the _Engineer_, that the inventor who could
supply in a really portable form a machine or apparatus that could give
out two or three horse power for a day would reap an enormous fortune.
Up to the present time, however, nothing of the kind has been placed
in the market. Gas is laid on to most houses now, and gas engines are
plenty enough, yet they do not meet the want which a storage battery may
be made yet perhaps to supply.

* * * * *

RECENT EXPERIMENTS AFFECTING THE RECEIVED THEORY OF MUSIC.

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