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Scientific American Supplement, No. 430, March 29, 1884 by Various

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NEW YORK, MARCH 29, 1884

Scientific American Supplement. Vol. XVII, No. 430.

Scientific American established 1845

Scientific American Supplement, $5 a year.

Scientific American and Supplement, $7 a year.

* * * * *


I. ENGINEERING, MECHANICS, ETC.--The Iron Industry In Brazil.--By
Prof. P. FEHRAND.--Methods of obtaining iron.--Operation
of the system.--Elaboration of the ore.--Setting up a forge.--
Selling price of iron

The Steamer Churchill, built by Messrs. Hall, Russell & Co., for
service at Natal.--With full page of illustrations

Three-Way Tunnels

Falconetti's Continuously Primed Siphon.--Manner of carrying a
water course over a canal, river, or road.--With engraving

The Weibel-Piccard System of Evaporating Liquids.--
2 illustrations

II. TECHNOLOGY.--Coal Gas as a Labor--saving Agent in Mechanical
Trades.--By T. FLETCHER.--Gas as fuel.--Arrangement of burners
for disinfection, for drying glue, albumen, etc.--Best burners.
--Gas bars for furnaces, etc.

Instantaneous Photography.--Several illustrations

paper read before the Society of Arts by A. RECKENZAUN, and
discussion on the same.--Advantages of electromotive power.--
Cost of same.--Experimental electric launches

First Experiments with the Electric Light.--Sir Humphry
Davy's experiments in 1813,--With two engravings

Electrical Grapnel for Submarine Cables and Torpedo Lines.--
3 figures

Hughes' New Magnetic Balance.--1 figure

Apparatus for Measuring Small Resistances.--With engraving
and diagram

Terrestrial Magnetism.--Magnetism on railways.--Synchronous

IV. ARCHITECTURE.--Adornments of the New Post Office at Leipzig.--
2 engravings

V. NATURAL HISTORY, ETC.--Comparison of Strength of Large
and Small Animals.--By W. N. LOCKINGTON

Oil in California

VI. HORTICULTURE, BOTANY. ETC.--The Dodder.--A new parasitic
plant.--With engraving

Recent Botanical Investigations

VII. MEDICINE, HYGIENE ETC.--Nutritive Value of Condiments.--By

VIII. MISCELLANEOUS.--Mont St. Michel, Normandy.--With engraving

* * * * *


The genus _Cuscuta_ contains quite a number of species which go under
the common name of dodder, and which have the peculiarily of living as
parasites upon other plants. Their habits are unfortunately too well
known to cultivators, who justly dread their incursions among cultivated
plants like flax, hops, etc.

All parasitic plants, or at least the majority of them, have one
character in common which distinguishes them at first sight. In many
cases green matter is wanting in their tissues or is hidden by a
livid tint that strikes the observer. Such are the Orobanchaccae, or
"broomropes," and the tropical Balanophoraceae. Nevertheless, other
parasites, such as the mistletoe, have perfectly green leaves.

However this may be, the naturalist's attention is attracted every time
he finds a plant deprived of chlorophyl, and one in which the leaves
seem to be wanting, as in the dodder that occupies us. In fact, as the
majority of parasites take their nourishment at the expense of the
plants upon which they fasten themselves, they have no need, as a
general thing, of elaborating through their foliar organs the materials
that their hosts derive from the air; in a word, they do not breathe
actively like the latter, since they find the elements of their
nutrition already prepared in the sap of their nurses. The dodders,
then, are essentially parasites, and their apparent simplicity gives
them a very peculiar aspect. Their leaves are wholly wanting, or are
indicated by small, imperceptible scales, and their organs of vegetation
are reduced to a stem and filiform branches that have obtained for them
the names of _Cheveux de Venus_ (Venus' Hair) and _Cheveux du Diable_
(devil's hair) in French, and gold thread in English. Because of their
destructive nature they have likewise been called by the unpoetic name
of hellweed; and, for the reason that they embrace their host plants so
closely, they have been called love weed and love vine.

When a seed of _Cuscuta_, germinates, no cotyledons are to be
distinguished. This peculiarity, however, the plant has in common with
other parasites, and even with some plants, such as orchids, that
vegetate normally. The radicle of the dodder fixes itself in the earth,
and the little stem rises as in other dicotyledons; but soon (for the
plantlet could not live long thus) this stem, which is as slender as a
thread, seeks support upon some neighboring plant, and produces upon
its surfaces of contact one or more little protuberances that shortly
afterward adhere firmly to the support and take on the appearance and
functions of cupping glasses. At this point there forms a prolongation
of the tissue of the dodder--a sort of cone, which penetrates the stalk
of the host plant. After this, through the increase of the stem and
branches of the parasite, the supporting plant becomes interlaced on
every side, and, if it does not die from the embraces of its enemy, its
existence is notably hazarded. It is possible for a _Cuscuta_ plant to
work destruction over a space two meters in diameter in a lucern or
clover field; so, should a hundred seeds germinate in an acre, it may be
easily seen how disastrous the effects of the scourge would prove.

These enemies of our agriculture were scarcely to be regarded as
injurious not very many years ago, for the reason that their sources of
development were wanting. Lucern and clover are comparatively recent
introductions into France, at least as forage plants. Other cultures are
often sorely tried by the dodder, and what is peculiar is that there are
almost always species that are special to such or such a plant, so that
the botanist usually knows beforehand how to determine the parasite
whose presence is made known to him. Thus, the _Cuscuta_ of flax, called
by the French _Bourreau du Lin_ (the flax's executioner), and by the
English, flax dodder, grows only upon this textile plant, the crop of
which it often ruins. On account of this, botanists call this species
Cuscuta epilinum. Others, such as C. Europaea, attack by preference hemp
and nettle. Finally, certain species are unfortunately indifferent and
take possession of any plant that will nourish them. Of this number is
the one that we are about to speak of.

Attempts have sometimes been made out of curiosity to cultivate exotic
species. One of the head gardeners at the Paris Museum received
specimens of _Cuscuta reflexa_ from India about two years ago, and,
having placed it upon a geranium plant, succeeded in cultivating it.
Since then, other plants have been selected, and the parasite has been
found to develop upon all of them. What adds interest to this species
is that its flowers are relatively larger and that they emit a pleasant
odor of hawthorn. Mr. Hamelin thinks that by reason of these advantages,
an ornamental plant might be made of it, or at least a plant that would
be sought by lovers of novelties. Like the majority of dodders, this
species is an annual, so that, as soon as the cycle of vegetation is
accomplished, the plant dies after flowering and fruiting. But here the
seeds do not arrive at maturity, and the plant has to be propagated by
a peculiar method. At the moment when vegetation is active, it is only
necessary to take a bit of the stem, and then, after previously lifting
a piece of the bark of the plant upon which it is to be placed, to apply
this fragment of _Cuscuta_ thereto (as in grafting), place the bark over
it, and bind a ligature round the whole. In a short time the graft will
bud, and in a few months the host plant will be covered with it.

The genus _Cuscuta_ embraces more than eighty species, which are
distributed throughout the entire world, but which are not so abundant
in cold as in warm regions.--_La Nature_.

[Illustration: A NEW EXOTIC DODDER. (_Cuscuta Reflexa_.)]

* * * * *


It is commonly said that there is a great difference between the
transpiration and evaporation of water in plants. The former takes place
in an atmosphere saturated with moisture, it is influenced by light,
by an equable temperature, while evaporation ceases in a saturated
atmosphere. M. Leclerc has very carefully examined this question, and he
concludes that transpiration is only the simple evaporation of water. If
transpiration is more active in the plant exposed to the sun, that is
due to the heat rays, and in addition arises in part from the fact that
the assimilating action of chlorophyl heats the tissues, which in turn
raises the temperature and facilitates evaporation.

As to transpiration taking place in a saturated atmosphere, it is a
mistake; generally there is a difference in the temperature of the plant
and the air, and the air is not saturated in its vicinity. In a word,
transpiration and evaporation is the same thing.

Herr Reinke has made an interesting examination of the action of light
on a plant. He has permitted a pencil of sun rays to pass through a
converging lens upon a cell containing a fragment of an aquatic plant.
He was enabled to increase the intensity of the light, so that it should
be stronger or weaker than the direct sunlight. He could thus vary its
intensity from 1/16 of that of direct sunlight to an intensity 64 times
stronger. The temperature was maintained constant.

Herr Reinke has shown that the chlorophyl action increases regularly
with the light for intensities under that of direct sunlight; but what
is unexpected, that for the higher intensities above that of ordinary
daylight the disengagement of oxygen remains constant.

M. Leclerc du Sablon has published some of his results in his work on
the opening of fruits. The influences which act upon fruit are external
and internal. The external cause of dehiscence is drying. We can open or
shut a fruit by drying or wetting it. The internal causes are related to
the arrangement of the tissues, and we may say that the opening of fruit
can be easily explained by the contraction of the ligneous fibers under
drying influences. M. Leclerc shows by experiment that the fibers
contract more transversely than longitudinally, and that the thicker
fibers contract the most. This he finds is connected with the opening of
dry fruits.

Herr Hoffman has recently made some interesting experiments upon the
cultivation of fruits.

It is well known that many plants appear to select certain mineral soils
and avoid others, that a number of plants which prefer calcareous soils
are grouped together as _calcicoles_, and others which shun such ground
as _calcifuges_. Herr Hoffman has grown the specimen which has been
cited by many authors as absolutely calcifugic. He has obtained strong
plants upon a soil with 53 per cent. of lime, and these have withstood
the severe winter of 1879-1880, while individuals of the same species
grown on silicious ground have failed. This will modify the ideas of
agriculturists, at least in regard to this plant.

Herr Schwarz has been engaged in the study of the fine hairs of roots.
According to this author, there is a maximum and minimum of humidity,
between which there lies a mean of moisture, most favorable for the
development of these capillary rootlets, and this amount of moisture
varies with different plants. He finds that this growth of hair-like
roots is conditioned upon the development of the main root from which it
springs. In a weak solution of brine these fine roots are suppressed,
while the growth of the main root is continued. The changes of the
_milieu_ lead to changes in the form of the hairs, rendering them even

Signor Savastano has ventured to criticise as exaggerated the views of
Muller, Lubbock, and Allen on the adaptation of flowers to insects,
having noticed that bees visit numbers of flowers, and extract their
honey without touching the stigmas or pistils. He has also found them
neglecting flowers which were rich in honey and visiting others much
poorer. These observations have value, but cannot be considered as
seriously impairing the multiplied evidences of plant adaptation to
insect life.

Mr. Camus has shown that the flora of a small group of hills, the
Euganean Mountains, west of the Apennines and south of the Alps, has a
peculiar flora, forming an island in the midst of a contrasted flora
existing about it. Here are found Alpine, maritime, and exotic plants
associated in a common isolation.--_Revue Scientifique_.

* * * * *


Among the most significant of the recent discoveries in botany, is that
respecting the continuity of the protoplasm from cell to cell, by means
of delicate threads which traverse channels through the cell walls. It
had long been known, that in the "sieve" tissues of higher plants there
was such continuity through the "sieve plates," which imperfectly
separated the contiguous cells. This may be readily seen by making
longitudinal sections of a fibro-vascular bundle of a pumpkin stem,
staining with iodine, and contracting the protoplasm by alcohol.
Carefully made specimens of the soft tissues of many plants have shown
a similar protoplasmic continuity, where it had previously been
unsuspected. Some investigators are now inclined to the opinion that
protoplasmic continuity may be of universal occurrence in plants.

* * * * *


[Footnote: A recent lecture before the Society of ATM, London.]


It is not my intention to treat this subject from a shipwright's point
of view. The title of this paper is supposed to indicate a mode of
propelling boats by means of electrical energy, and it is to this motive
power that I shall have the honor of drawing your attention.

The primary object of a launch, in the modern sense of the word, lies
in the conveyance of passengers on rivers and lakes, less than for the
transport of heavy goods; therefore, it may not be out of place to
consider the conveniences arising from the employment of a motive power
which promises to become valuable as time and experience advance. In a
recent paper before the British Association at Southport, I referred to
numerous experiments made with electric launches; now it is proposed
to treat this subject in a wider sense, touching upon the points of
convenience in the first place; secondly, upon the cost and method of
producing the current of electricity; and thirdly, upon the construction
and efficiency of the propelling power and its accessories.

Whether it is for business, pleasure, or war purposes a launch should
be in readiness at all times, without requiring much preparation or
attention. The distances to be traversed are seldom very great, fifty to
sixty miles being the average.

Nearly the whole space of a launch should be available for the
accommodation of passengers, and this is the case with an electrically
propelled launch. We have it on good authority, that an electric launch
will accommodate nearly double the number of passengers that a
steam launch of the same dimensions would; therefore, for any given
accommodation we should require a much smaller vessel, demanding less
power to propel it at a given rate of speed, costing less, and affording
easier management.

A further convenience arising from electromotive power is the absence of
combustibles and the absence of the products of combustion-matters of
great importance; and for the milder seasons, when inland navigation
is principally enjoyed, the absence of heat, smell, and noise, and,
finally, the dispensing with one attendant on board, whose wages, in
most cases, amount to as much or more than the cost of fuel, besides the
inconvenience of carrying an additional individual.

I do not know whether the cost of motive power is a serious
consideration with proprietors of launches, but it is evident that if
there be a choice between two methods of equal qualities, the most
economical method will gain favor. The motive power on the electric
launch is the electric current; we must decide upon the mode of
procuring the current. The mode which first suggested itself to
Professor Jacobi, in the year 1838, was the primary battery, or the
purely chemical process of generating electricity.

Jacobi employed, in the first instance, a Daniell's battery, and in
later experiments with his boat on the river Neva, a Grove's battery.
The Daniell's battery consisted of 320 cells containing plates of copper
and zinc; the speed attained by the boat with this battery did not reach
one mile and a quarter per hour; when 64 Grove cells were substituted,
the speed came to two and a quarter miles per hour; the boat was 38
feet long. 71/2 beam, and 3 feet deep. The electromotor was invented by
Professor Jacobi; it virtually consisted of two disks, one of which was
stationary, and carried a number of electromagnets, while the other disk
was provided with pieces of iron serving as armatures to the pole pieces
of the electromagnets, which were attracted while the electric current
was alternately conveyed through the bobbins by means of a commutator,
producing continuous rotation.

We are not informed as to the length of time the batteries were enabled
to supply the motor with sufficient current, but we may infer from the
surface of the acting materials in the battery that the run was rather
short; the power of the motor was evidently very small, judging by the
limited speed obtained, but the originality of Jacobi deserves comment,
and for this, as well as for numerous other researches, his name will be
remembered at all times.

It may not be generally known that an electric launch was tried for
experimental purposes, on a lake at Pentlegaer, near Swansea. Mr. Robert
Hunt, in the discussion of his paper on electromagnetism before the
Institution of Civil Engineers in 1858, mentioned that he carried on an
extended series of experiments at Falmouth, and at the instigation of
Benkhausen, Russian Consul-General, he communicated with Jacobi upon the
subject. In the year 1848, at a meeting of the British Association at
Swansea, Mr. Hunt was applied to, by some gentlemen connected with the
copper trade of that part, to make some experiments on the electrical
propulsion of vessels; they stated, that although electricity might
cost thirty times as much as the power obtained from coal it would,
nevertheless, be sufficiently economical to induce its employment for
the auxiliary screw ships employed in the copper trade with South

The boat at Swansea was partly made under Mr. (now Sir William) Grove's
directions, and the engine was worked on the principle of the old toys
of Ritchie, which consisted of six radiating poles projecting from a
spindle, and rotating between a large electro-magnet. Three persons
traveled in Hunt's boat, at the rate of three miles per hour. Eight
large Grove's cells were employed, but the expense put it out of
question as a practical application.

Had the Gramme or Siemens machine existed at that time, no doubt the
subject would have been further advanced, for it was not merely the cost
of the battery which stood in the way, but the inefficient motor, which
returned only a small fraction of the power furnished by the zinc.

Professor Silvanus Thompson informs us that an electric boat was
constructed by Mr. G. E. Dering, in the year 1856, at Messrs. Searle's
yard, on the River Thames; it was worked by a motor in which rotation
was effected by magnets arranged within coils, like galvanometer
needles, and acted on successively by currents from a battery.

From a recent number of the _Annales de l'Electricite_, we learn that
Count de Moulins experimented on the lake in the Bois de Boulogne, in
the year 1866, with an iron flat-bottomed boat, carrying twelve persons.
Twenty Bunsen cells furnished the current to a motor on Froment's
principle turning a pair of paddle wheels.

In all these reports there is a lack of data. We are interested to
know what power the motors developed, the time and speed, as well as
dimensions and weights.

Until Trouve's trip on the Seine, in 1881, and the launch of the
Electricity on the Thames, in 1882, very little was known concerning the
history of electric navigation.

M. Trouve originally employed Plante's secondary battery, but afterward
reverted to a bichromate battery of his own invention. In all the
primary batteries hitherto applied with advantage, zinc has been used as
the acting material. Where much power is required, the consumption of
zinc amounts to a formidable item; it costs, in quantity, about 3d. per
pound, and in a well arranged battery a definite quantity of zinc is
transformed. The final effect of this transformation manifests itself in
electrical energy, amounting to about 746 watts, or one electrical horse
power for every two pounds of this metal consumed per hour. The cost of
the exciting fluid varies, however, considerably; it may be a solution
of salts, or it may be dilute acid. Considering the zinc by itself, the
expense for five electrical or four mechanical horse power through an
efficient motor, in a small launch, would be 2s. 6d. per hour. Many
persons would willingly sacrifice 2s. 6d per hour for the convenience,
but a great item connected with the employment of zinc batteries is
in the exciting fluid, and the trouble of preparing the zinc plates
frequently. The process of cleaning, amalgamating and refilling is so
tedious, that the use of primary batteries for locomotive purposes is
extremely limited. To recharge a Bunsen, Grove, or bichromate battery,
capable of giving six or seven hours' work at the rate of five
electrical horse power, would involve a good day's work for one man; no
doubt he would consider himself entitled to a full day's wages, with the
best appliances to assist him in the operation.

Several improved primary batteries have recently been brought out, which
promise economical results. If the residual compound of zinc can be
utilized, and sold at a good price, then the cost of such motive power
may be reduced in proportion to the value of those by-products.

For the purpose of comparison, let us now employ the man who would
otherwise clean and prepare the primary cells, at engine driving. We let
him attend to a six horse power steam engine, boiler, and dynamo machine
for charging 50 accumulators, each of a capacity of 370 ampere hours, or
one horse power hour. The consumption of fuel will probably amount to 40
lb. per hour, which, at the rate of 18s. a ton, will give an expenditure
of nearly 4d. per hour. The energy derived from coal in the accumulator
costs, in the case of a supply of five electrical horse power for seven
hours, 2s. 9d.; the energy derived from the zinc in a primary battery,
supplying five electrical horse power for seven hours, would cost 17s.

It is hardly probable that any one would lay down a complete plant,
consisting of a steam or gas engine and dynamo, for the sole purpose of
charging the boat cells, unless such a boat were in almost daily use, or
unless several boats were to be supplied with electrical power from one
station. In order that electric launches may prove useful, it will be
desirable that charging stations should be established, and on many of
the British and Irish rivers and lakes there is abundance of motive
power, in the shape of steam or gas engines, or water-wheels.

A system of hiring accumulators ready for use may, perhaps, best satisfy
the conditions imposed in the case of pleasure launches.

It is difficult to compile comparative tables showing the relative
expenses for running steam launches, electric launches with secondary
batteries, and electric launches with primary zinc batteries; but I
have roughly calculated that, for a launch having accommodation for a
definite number of passengers, the total costs are as 1, 2.5, and 12
respectively, steam being lowest and zinc batteries highest.

The accumulators are, in this case, charged by a small high pressure
steam engine, and a very large margin for depreciation and interest on
plant is added. The launch taken for this comparison must run during
2,000 hours in the year, and be principally employed in a regular
passenger service, police and harbor duties, postal service on the lakes
and rivers of foreign countries, and the like.

The subject of secondary batteries has been so ably treated by Professor
Silvanus Thompson and Dr. Oliver Lodge, in this room, that I should
vainly attempt to give you a more complete idea of their nature. The
improvements which are being made from time to time mostly concern
mechanical details, and although important, a description will scarcely
prove interesting.

A complete Faure-Sellon-Volckmar cell, such as is used in the existing
electric launches, is here on the table; this box weighs, when ready
for use, 56 lb.; and it stores energy equal to one horse power for one
hour=1,980,000 foot pounds, or about one horse power per minute for each
pound weight of material. It is not advantageous to withdraw the whole
amount of energy put in; although its charging capacity is as much as
370 ampere hours, we do not use more than 80 per cent., or 300 ampere
hours; hence, if we discharge these accumulators at the rate of 40
amperes, we obtain an almost constant current for 71/2 hours: one cell
gives an E.M.F. of two volts. In order to have a constant power of one
horse for 71/2 hours, at the rate of 40 amperes discharge, we must have
more than nine cells per electrical horsepower; and 47 such cells will
supply five electrical horse power for the time stated, and these 47
cells will weigh 2,633 lb.

We could employ half the number of cells by using them at the rate of
80 amperes, but then they will supply the power for less than half the
time. The fact, however, that the cells will give so high a rate of
discharge for a few hours is, in itself, important, since we are enabled
to apply great power if desirable; the 47 cells above referred to can
be made to give 10 or 12 electrical horse power for over two hours, and
thus propel the boat at a very high speed, provided that the motor is
adapted to utilize such powerful currents.

The above mentioned weight of battery power--viz., 2,632 lb., to
which has to be added the weight of the motor and the various
fittings--represents, in the case of a steam launch, the weight of
coals, steam boiler, engine, and fittings. The electro motor capable of
giving four horse power on the screw shaft need not weigh 400 lb. if
economically designed; this added to the weight of the accumulators, and
allowing a margin for switches and leads, brings the whole apparatus up
to about 28 cwt.

An equally powerful launch engine and boiler, together with a maximum
stowage of fuel, will weigh about the same. There is, however, this
disadvantage about the steam power, that it occupies the most valuable
part of the vessel, taking away some eight or nine feet of the widest
and most convenient part, and in a launch of twenty-four feet length,
requiring such a power as we have been discussing, this is actually
one-third of the total length of the vessel, and one-half of the
passenger accommodation; therefore, I may safely assert that an electric
launch will carry about twice as many people as a steam launch of
similar dimensions.

The diagram on the wall represents sections of an electric launch built
by Messrs. Yarrow and Company, and fitted up by the Electrical Power
Storage Company, for the recent Electrical Exhibition in Vienna. She has
made a great number of successful voyages on the River Danube during the
autumn. Her hull is of steel, 40 feet long and 6 feet beam, and there
are seats to accommodate forty adults comfortably. Her accumulators are
stowed away under the floor, so is the motor, but owing to the lines of
the boat the floor just above the motor is raised a few inches. This
motor is a Siemens D2 machine, capable of working up to seven horse
power with eighty accumulators.

In speaking of the horse power of an electro motor, I always mean the
actual power developed in the shaft, and not the electrical horse power;
this, therefore, should not be compared to the indicated horse power of
a steam engine.

I am indebted to Messrs. Yarrow for the principal dimensions and other
particulars of a high pressure launch engine and boiler, such as would
be suitable for this boat. From these dimensions I prepared a second
diagram representing the steam power, and when placed in position it
will show at a glance how much space this apparatus will occupy. The
total length lost in this way amounts to 12 feet, leaving for testing
capacity only 15 feet, while that of the electric launch is 27 feet
on each side of the boat; thus the accommodation is as fifteen to
twenty-seven, or as twenty-two passengers to forty, in favor of the
electric launch.

Comparing the relative weights of the steam power and the electric power
for this launch, we find that they are nearly equal--each approaches 50
cwt; but in the case of the steam launch we include 10 cwt. of coals,
which can be stowed into the bunkers, and which allow fifteen hours
continuous steaming, whereas the electric energy stored up will only
give us seven and a half hours with perfect safety.

I have here allowed 8 lb. of coal per indicated horse power per hour,
and 10 horse power giving off 7 mechanical horse power on the screw
shaft; this is an example of an average launch engine. There are launch
engines in existence which do not consume one-half that amount of fuel,
but these are so few, so rare, and so expensive, that I have neglected
them in this account.

Not many years ago, a steam launch carrying a seven hours supply of fuel
was considered marvelous.

Our present accumulaton supplies 33,000 foot pounds of work per pound of
lead, but theoretically one pound of lead manifests an energy equal to
360,000 foot pounds in the separation from its oxide; and in the case of
iron, Prof. Osborne Reynolds told us in this place, the energy evolved
by its oxidation is equivalent to 1,900,000 foot pounds per pound of
metal. How nearly these limits may be approached will he the problem
of the chemist; to prophesy is dangerous, while science and its
applications are advancing at this rapid rate.

Theoretically, then, with our weight of fully oxidized lead we should be
able to travel for 82 hours; with the same weight of iron for 430 hours,
or 18 days and nights continually, at the rate of 8 miles per hour, with
one change. Of course, these feats are quite impossible. We might as
well dream of getting 5 horse power out of a steam engine for one pound
of coal per hour.

While the chemist is busy with his researches for substances and
combinations which will yield great power with small quantities of
material, the engineer assiduously endeavors to reconvert the chemical
or electrical energy into mechanical work suitable to the various needs.

To get the maximum amount of work with a minimum amount of weight, and
least dimensions combined with the necessary strength is the province
of the mechanical engineer--it is a grand and interesting study; it
involves many factors; it is not, as in the steam engine and hydraulic
machine, a matter of pressures, tension and compression, centrifugal and
static forces, but it comprises a still larger number of factors, all
bearing a definite relation to each other.

With dynamo machines the aim has been to obtain as nearly as possible
as much electrical energy out of the machine as has been put in by the
prime mover, irrespective of the quantity of material employed in its
construction. Dr. J. Hopkinson has not only improved upon the Edison
dynamo, and obtained 94 per cent. of the power applied in the form of
electrical energy, but he got 50 horse power out of the same quantity of
iron and copper where Edison could only get 20 horsepower--and, though
the efficiency of this generator is perfect, it could not be called an
efficient motor, suitable for locomotion by land or water, because it
is still too heavy. An efficient motor for locomotion purposes must not
only give out in mechanical work as nearly as possible as much as the
electrical energy put in, but it must be of small weight, because it has
to propel itself along with the vehicle, and every pound weight of
the motor represents so many foot pounds of energy used in its own
propulsion; thus, if a motor weighed 660 pounds, and were traveling at
the rate of 50 feet per minute, against gravitation, it would expend
33,000 foot pounds per minute in moving itself, and although this
machine may give 2 horse power, with an efficiency of 90 per cent.
it would, in the case of a boat or a tram-car, be termed a wasteful
machine. Here we have an all-important factor which can be neglected,
to a certain extent, in the dynamo as a generator, although from an
economical point of view excessive weight in the dynamo must also be
carefully avoided.

The proper test for an electro-motor, therefore, is not merely its
efficiency, or the quotient of the mechanical power given out, divided
by the electrical energy put in, but also the number of feet it could
raise its own weight in a given space of time, with a given current, or,
in other words, the number of foot pounds of work each pound weight of
the motor would give out.

The Siemens D2 machine, as used in the launch shown in the diagram on
the wall, is one of the lightest and best motors, it gives 7 horse power
on the shaft, with an expenditure of 9 electrical horsepower, and it
weighs 658 lb.; its efficiency, therefore, 7/5 or nearly 78 per cent.;
but its "coefficient" as an engine of locomotion is 351--that is to say,
each pound weight of the motor will yield 351 foot pounds on the shaft.
We could get even more than 7 horse power out of this machine, by either
running it at an excessive speed, or by using excessive currents; in
both cases, however, we should shorten the life of the apparatus.

An electro-motor consists, generally, of two or more electro-magnets so
arranged that they continually attract each other, and thereby convey
power. As already stated, there are numerous factors, all bearing a
certain relationship to each other, and particular rules which hold
good in one type of machine will not always answer in another, but the
general laws of electricity and magnetism must be observed in all cases.
With a given energy expressed in watts, we can arrange a quantity of
wire and iron to produce a certain quantity of work; the smaller the
quantity of material employed, and the larger the return for the energy
put in, the greater is the total efficiency of the machine.

Powerful electro-magnets, judiciously arranged, must make powerful
motors. The ease with which powerful electro-magnets can be constructed
has led many to believe that the power of an electro-motor can be
increased almost infinitely, without a corresponding increase of energy
spent. The strongest magnet can be produced with an exceedingly
small current, if we only wind sufficient wire upon an iron core. An
electro-magnet excited by a tiny battery of 10 volts, and, say,
one ampere of current, may be able to hold a tremendous weight in
suspension, although the energy consumed amounts to only 10 watts, or
less than 1/75 of a horse power, but the suspended weight produces no
mechanical work. Mechanical work would only be done if we discontinued
the flow of the current, in which case the said weight would drop; if
the distance is sufficiently small, the magnet could, by the application
of the current from the battery, raise the weight again, and if that
operation is repeated many times in a minute, then we could determine
the mechanical work performed. Assuming that the weight raised is 1,000
lb., and that we could make and break the current two hundred times
a minute, then the work done by the falling mass could, under no
circumstances, equal 1/75 of a horse-power, or 440 foot-pounds; that is,
1,000 lb. lifted 2.27 feet high in a minute, or about one-eighth of an
inch for each operation: hence the mere statical pull, or power of the
magnet, does in no way tend to increase the energy furnished by the
battery or generator, for the instant we wish to do work we must have
motion--work being the product of mass and distance.

Large sums of money have virtually been thrown away in the endeavor
to produce energy, and there are intelligent persons who to this day
imagine that, by indefinitely increasing the strength of a magnet, more
power may be got out of it than is put in.

Large field-magnets are advantageous, and the tendency in the
manufacture of dynamo machines has been to increase the mass of iron,
because with long and heavy cores and pole pieces there is a steady
magnetism insured, and therefore a steady current, since large masses
of iron take a long time to magnetize and demagnetize; thus very slight
irregularites in the speed of an armature are not so easily perceived.
In the case of electro-motors these conditions are changed. In the first
place, we assume that the current put through the coils of the magnets
is continuous; and secondly, we can count upon the momentum of the
armature, as well as the momentum of the driven object, to assist us
over slight irregularities. With electric launches we are bound
to employ a battery current, and battery currents are perfectly
continuous--there are no sudden changes; it is consequently a question
as to how small a mass of iron we may employ in our dynamo as a motor
without sacrificing efficiency. The intensity of the magnetic field
must be got by saturating the iron, and the energy being fixed, this
saturation determines the limit of the weight of the iron. Soft wrought
iron, divided into the largest possible number of pieces, will serve
our purpose best. The question of strength of materials plays also an
important part. We cannot reduce the quantity and division to such a
point that the rigidity and equilibrium of the whole structure is in any
way endangered.

The armature, for instance, must not give way to the centrifugal forces
imposed upon it, nor should the field magnets be so flexible as to yield
to the statical pull of the magnetic poles. The compass of this paper
does not permit of a detailed discussion of the essential points to be
observed in the construction of electro-motors; a reference to the main
points, may, however, be useful. The designer has, first of all, to
determine the most effective positions of the purely electrical and
magnetic parts; secondly, compactness and simplicity in details;
thirdly, easy access to such parts as are subject to wear and
adjustment; and, fourthly, the cost of materials and labor. The internal
resistance of the motor should be proportioned to the resistances of the
generator and the conductors leading from the generator to the receiver.

The insulation resistances must be as high as possible; the insulation
can never be too good. The motor should he made to run at that speed
at which it gives the greatest power with a high efficiency, without
heating to a degree which would damage the insulating material.

Before fixing a motor in its final position, it should also be tested
for power with a dynamometer, and for this purpose a Prony brake answers
very well.

An ammeter inserted in the circuit will show at a glance what current is
passing at any particular speed, and voltmeter readings are taken at the
terminals of the machine, when the same is standing still as well as
when the armature is running, because the E.M.F. indicated when the
armature is at rest alone determines the commercial efficiency of the
motor, whereas the E M.F. developed during motion varies with the speed
until it nearly reaches the E.M.F. in the leads; at that point the
theoretical efficiency will be highest.

Calculations are greatly facilitated, and the value of tests can be
ascertained quickly, if the constant of the brake is ascertained; then
it will be simply necessary to multiply the number of revolutions and
the weight at the end of the lever by such a constant, and the product
gives the horse power, because, with a given Prony brake, the only
variable quantities are the weight and the speed. All the observations,
electrical and mechanical, are made simultaneously. The electrical horse
power put into the motor is found by the well known formula C x E / 746;
this simple multiplication and division becomes very tedious and even
laborious if many tests have to be made in quick succession, and to
obviate this trouble, and prevent errors, I have constructed a horse
power diagram, the principle of which is shown in the diagram (Fig. 1).

Graphic representations are of the greatest value in all comparative
tests. Mr. Gisbert Kapp has recently published a useful curve in the
_Electrician_, by means of which one can easily compare the power and
efficiency at a glance (Fig. 2).

The speeds are plotted as abscissae, and the electrical work absorbed
in watts divided by 746 as ordinates; then with a series-wound motor we
obtain the curve, EE. The shape of this curve depends on the type of
the motor. Variation of speed is obtained by loading the brake with
different weights. We begin with an excess of weight which holds the
motor fast, and then a maximum current will flow through it without
producing any external work. When we remove the brake altogether, the
motor will run with a maximum speed, and again produce no external work,
but in this case very little current will pass; this maximum speed is om
on the diagram. Between these two extremes external work will be done,
and there is a speed at which this is a maximum. To find these speeds we
load the brake to different weights, and plot the resulting speeds and
horse powers as abscissae and ordinates producing the curve, BB. Another

e = B/E

made with an arbitrary scale, gives the commercial efficiency; the speed
for a maximum external horse power is o a, and the speed for the highest
efficiency is represented by o b. In practice it is not necessary to
test a motor to the whole limits of this diagram; it will be sufficient
to commence with a speed at which the efficiency becomes appreciable,
and to leave off with that speed which renders the desired power.

I have now to draw your attention to a new motor of my own invention, of
the weight of 124 lb., which, at 1,550 revolutions, gives 31 amperes and
61.5 volts at terminals. The mechanical horse power is 1.37, and the
coefficient 373.

Armature resistance 0.4 w.
Field-magnet resistance 0.17 w.
Insulation resistance 1,500,000 w.

This motor was only completed on the morning before reading the paper;
it could not, therefore, be tested as to its various capacities.

We have next to consider the principle of applying the motive power to
the propulsion of a launch. The propellers hitherto practically applied
in steam navigation are the paddle-wheel and the screw. The experience
of modern steam navigation points to the exclusive use and advantage of
the screw propeller where great speed of shaft is obtainable, and the
electric engine is pre-eminently a high-speed engine, consequently the
screw appears to be most suitable to the requirements of electric boats.
By simply fixing the propeller to the prolonged motor shaft, we complete
the whole system, which, when correctly made, will do its duty in
perfect order, with an efficiency approaching theory to a high degree.


Draw a square, A B C D--divide B C into 746 parts, and C D into 1,000
parts, or, generally, let a division on C D be 0.746 of a division on B
C, so that we can use the horizontal lines cutting A B as a horse power
scale. A B, in the above diagram, gives 1,000 horse power, if the line
B C represents 746 volts, and C D 1,000 amperes. Let x = any number of
volts, y the amperes, and h the horse power, then

h/x = y/100 :. h = xy/746

A fine wire or thread stretched from o as a center to the required
division on C D will facilitate references.]

Whatever force may be imparted to the water by a propeller, such force
can be resolved into two elements, one of which is parallel, and the
other in a plane at right angles to the keel. The parallel force alone
has the propelling effect; the screw, therefore, should always be so
constructed that its surfaces shall be chiefly employed in driving the
water in a direction parallel to the keel from stem to stern.

[Illustration: Fig. 2--KAPP'S DIAGRAM.]

It is evident that a finely pitched screw, running at a high velocity,
will supply these conditions best. With that beautiful screw lying on
this table, and made by Messrs. Yarrow, 95 per cent. of efficiency
has been obtained when running at a speed of over 800 revolutions per
minute--that is to say, only 5 per cent was lost in slip.

Reviewing the various points of advantage, it appears that electricity
will, in time to come, be largely used for propelling launches, and,
perhaps, something more than launches.

In conclusion, quoting Dr. Lardner's remarks on the subject of steam
navigation of nearly fifty years ago, he said:

"Some, who, being conversant with the actual conditions of steam
engineering as applied to navigation, and aware of various commercial
conditions which must affect the problem, were enabled to estimate
calmly and dispassionately the difficulties and drawbacks, as well as
the disadvantages, of the undertaking, entertained doubts which clouded
the brightness of their hopes, and warned the commercial world against
the indulgence of too sanguine anticipation of the immediate and
unqualified realization of the project. They counseled caution and
reserve against an improvident investment of extensive capital in
schemes which still be only regarded as experimental, and which might
prove its grave. But the voice of remonstrance was drowned amid the
enthusiasm excited by the promise of an immediate practical realization
of a scheme so grand.

"It cannot," he continues, "be seriously imagined that any one who
had been conversant with the past history of steam navigation could
entertain the least doubt of the abstract practicability of a steam
vessel making the voyage between Bristol and New York. A steam vessel,
having as cargo a couple of hundred tons of coals, would, _caeteris
paribus_, be as capable of crossing the Atlantic as a vessel
transporting the same weight of any other cargo."

Dr. Lardner is generally credited with having asserted that a steam
voyage across the Atlantic was "a physical impossibility," but in the
work from which I took the liberty of copying his words he denies the
charge, and says that what he did affirm was, that long sea voyages
could not at that time be maintained with that regularity and certainty
which are indispensable to commercial success, by any revenue which
could be expected from traffic alone.

The practical results are well known to us. History repeats itself, and
the next generation may put on record our week attempts, our doubts and
fears of this day. Whether electricity will ever rival steam, remains
yet to be proved; we may be on the threshold of great things. The
premature enthusiasm has subsided, and we enter upon the road of steady

Mr. Wm. H. Preece, the chairman, in inviting discussion, said that no
doubt those present would like to know something about the cost of such
a boat as Mr. Reckenzaun described, and he hoped that gentleman would
give them some information on that point.

Admiral Selwyn thought Mr. Reckenzaun was a little below the mark when
he talked about the dream of getting 5 horse power for one pound--he
would not say of coal, but of fuel. For some months he had seen 1/2 lb. of
fuel produce 1 horse power, and he knew it could be done. That fuel was
condensed concentrated fuel in the shape of oil. When this could be
done, electrical energy also could be obtained much cheaper, but if it
were extended to yachts, he thought that would be as far as any one now
present could be expected to see it go. Still he thought there was a
future for it, and that future would be best advanced by considering the
question on which he had touched. First, the employment of a cheaper
mode of getting the power in the steam engine; and, secondly, a cheaper
and higher secondary battery. In a railway train weight was a formidable
affair, but in a floating vessel it was still more important. He did
not think, however, that a light secondary battery was by any means an
impossibility. Mr. Loftus Perkins had actually produced by improvements
in the boiler and steam engine two great things: first, one indicated
horse power for a pound of fuel per hour, and next he had devised a
steam engine of 100 horse power, of a weight of only 84 lb. per horse
power, instead of 304 lb., which was about the average. Those were two
enormous steps in advance, and under a still more improved patent law he
had no doubt things would be brought forward which would show a still
greater progress. Within the last fifteen days, nearly 2,000 patents
had been taken out, as against 5,000 in the whole of the previous year,
which showed how operative a very small and illusory inducement had been
to encourage invention. He had long been known as an advocate of patent
law reform, and, therefore, felt bound to lose no opportunity of calling
attention to its importance. Invention was in the hands of the inventor,
the creator of trade. If, without robbing anybody, one wished to produce
property, it must be done by improving manufactures as a consequence
of inventions. In one instance alone it bad been proved that a single
invention had been the means of introducing twenty millions annually,
upon which income tax was paid.

Mr. Crampton said he did not think steam could ever compete with
electricity, under certain circumstances; but, at the same time, it
would be a long time before it was superseded. He should like very much
to see the compressed oil, one-sixth of a pound of which would give 1
horse power per hour.

Admiral Selwyn said he had seen a common Cornish boiler doing it years

Mr. Crampton said it had never come under his notice, and he had no
hesitation in saying that no such duty ever was performed by any oil,
because he never heard of any oil which evaporated more than eighteen to
twenty-two pounds of water per pound. However, he was delighted to hear
of such progress being made, and though he had been for so many years
connected with steam, he never expected it would last forever. He was
now making experiments for some large shipowners, for the purpose of
facilitating feeding and doing away with dust, but let him succeed to
what extent he might, steam would never compete with electricity for
such small vessels as these launches.

The Chairman asked if he rightly understood Admiral Selwyn that he had
recently seen an invention in which one-sixth of a pound of condensed
fuel would give 1 horse power per hour.

Admiral Selwyn said it was now some years ago since he saw this going
on, but the persons who did it did not know how or why it was done.
He had studied the question for the last ten years, and now knew the
_rationale_ of it, and would be prepared shortly to publish it. He knew
that 22 was the theoretical calorific value of the pound of oil, and
never supposed that oil alone would give 46 lb., which he saw it doing.
He had found out that by means of the oil forming carbon constantly in
the furnace, the hydrogen of the steam was burned, and that it was a
fallacy to suppose that an equal quantity of heat was used in raising
steam, at a pressure of, say, 120 lb. to the square inch, as the
hydrogen was capable of developing when properly burned. There were,
however, conditions under which alone that combustion could take
place--one being that the heat of the chamber must be 3,700 deg., and that
carbon must be constantly formed.

Mr. Gumpel said with regard to the general application of electricity to
the propulsion of vessels as well as to railway trains, he believed that
many of those present would live to see electricity applied to that
purpose, because there were so many minds now applied to the problem,
that before long he had no doubt we should see coal burned in batteries,
as it was now burned in steam boilers. The utmost they could do, then,
would be about 50 per cent. less than Admiral Selwyn said could be
accomplished with condensed fuel. He could not but wonder where Admiral
Selwyn obtained his information, knowing that a theoretically perfect
heat engine would only give 23 per cent. of the absolute heat used,
and that a pound of the best coal would give but 8,000 and hydrocarbon
13,000 heat units, while hydrogen would give 34,000; and calculating it
out, how was it possible to get out of one-sixth of a pound of carbon,
or any hydrocarbon, the amount of power stated? No doubt, when Admiral
Selwyn applied the knowledge which physicists would give him of the
amount of power which could be got out of a certain amount of carbon and
hydrogen, he would find that there was a mistake somewhere.

Mr. Reckenzaun, in reply, said it would be very difficult to answer
the question put by the Chairman, as to the cost of an electric
launch--quite as difficult as to say what would be the cost of a steam
launch. It depended on the fittings, the ornamental part, the power
required, and the time it was required to run. If such a launch were
to run constantly, two sets of accumulators would be required, one to
replace the other when discharged. This could be easily done, the floor
being made to take up, and the cells could be changed in a few minutes
with proper appliances. As to Admiral Selwyn's remarks about one-sixth
of a pound of fuel per horse power, he had never heard of such a thing
before, and should like to know more about it. Mr. Loftus Perkins'
new steam engine was a wonderful example of modern engineering. A
comparatively small engine, occupying no more space than that of a steam
launch of considerable dimensions, developed 800 horse power indicated.
From a mechanical point of view, this engine was extremely interesting;
it had four cylinders, but only one crank and one connecting rod; and
there were no dead centers. The mechanism was very beautiful, but would
require elaborate diagrams to explain. Mr. Perkins deserved the greatest
praise for it, for in it he had reduced both the weight of the engine
and the consumption of fuel to a minimum. He believed he used coke and
took one pound per horse power. He should not like to cross the Channel
in the electric launch, if there was a heavy sea on, for shaking
certainly did not increase the efficiency of the accumulators, but a
fair amount of motion they could stand, and they had run on the Thames,
by the side of heavy tug boats causing a considerable amount of swell,
without any mishap. Of course each box was provided with a lid, and the
plates were so closely packed that a fair amount of shaking would not
affect them; the only danger was the spilling of the acid. Mr. Crohne
had remarked that a torpedo boat of that size would have 100 indicated
horse power, but then the whole boat would be filled with machinery.
What might be done with electricity they had, as yet, no idea of. At
present, they could only get 33,000 foot pounds from 1 lb. of lead and
acid, though, theoretically, they ought to get 360,000 foot pounds. Iron
in its oxidation would manifest theoretically 1,900,000 foot pounds
per lb. of material. As yet they had not succeeded in making an iron
accumulator; if they could, they would get about six or seven times
the energy for the same weight of material, or could reduce the
weight proportionately for the same power, and in that way they might
eventually get 70 horse power in a boat of that size, because the weight
of the motor was not great. With regard to the formation of a film on
the surface, no doubt a film of sulphate of lead was formed if the
battery stood idle, but it did not considerably reduce its efficiency;
as soon as it was broke through by the energy being evolved from it, it
would give off its maximum current. They knew by experience that, with
properly constructed accumulators, 80 per cent. of the energy put into
them was returned in work. It was quite certain, as Mr. Crampton said,
that it would be a long time before steam was superseded: he did not
prophesy at all; and he entitled his paper "Electric Launches," because
it would be presumptuous to speak of anything more until larger vessels
had been made and tried. With regard to Mr. Gumpel's remark on the
friction of the propeller, he would say that it was constructed to run
900 revolutions; if it were driven by a steam engine, and the speed
reduced to 300, not only would the pitch have to be altered, but the
surface would have to be larger, which would entail more friction. Mr.
Crohne would bear him out that they lost only 5 per cent. by slip and
friction combined, on an average of a great number of trials, both with
and against the current.

The Chairman in proposing a vote of thanks to Mr. Reckenzaun, said he
rejoiced to find that that gentleman had proved, to one man at least,
that his views had been mistaken. He found in these days of the
practical applications of electricity, that the ideas of most practical
men were gradually being proved to be mistaken, and every day new facts
were being discovered, which led them to imagine that as yet they were
only on the shore of an enormous ocean of knowledge. It was quite
impossible to say what these electric launches would lead to. Certain
points of great importance had been pointed out; they gave great room
and they were always ready. For lifeboat and fire engine purposes, as
Captain Shaw pointed out at Vienna, this was of great consequence.

At first they were led to believe that there was great stability, but
that idea had been a little shaken, not as to the boat itself, but as
to the influence of the motion of the water upon the constancy of the
cells. But these boats were only intended for smooth water, and if
they could not be adapted for rough water, he feared Admiral Selwyn's
suggestion of the application of this principle to lifeboats would fall
to the ground; but if secondary batteries were not calculated as yet
to stand rough usage, it only required probably some thought on Mr.
Reckenzaun's part to make them available even in a gale. Enormous
strides were being made with regard to these batteries. No one present
had been a greater skeptic with regard to them at first than be himself;
but after constant experiments--employing them, as he had done for many
months, for telegraphic purposes--he was gradually coming to view them
with a much more favorable eye. The same steps which had rendered all
scientific notions practicable, had gradually eliminated the faults
which originally existed, and they were now becoming good, sound,
available instruments. At present, he could only regard this electric
launch as a luxury. He had hoped that Mr. Reckenzaun would have been
able to say something which would have enabled poor men to look forward
to the time when they might enjoy themselves in them on the river; but
he was told at Vienna, when he enjoyed two or three trips in this boat
on the Danube, that her cost would be about L800, which was a little too
much for most people. They wanted something more within their reach,
so that at various points on the river they might see small engines
constantly at work supplying energy to secondary batteries, and so that
they might start on a Friday evening, and go up as far as Oxford, or
higher, and come down again on Monday morning. He must congratulate Mr.
Reckenzaun on the excellent diagrams he had constructed. The trouble of
calculating figures of this sort was very great when making experiments;
and the use of diagrams and curves expedited the labor very much. At
present they were passing through a stage of electrical depression;
robbery had been committed on a large scale; the earnings of the poor
had been filched out of their pockets by sanguine company promotors; an
enormous amount of money had been lost, and the result had been that
confidence was, to a great extent, destroyed; but those who had been
wise enough to keep their money in their pockets, and to read the papers
read in that room, must have seen that there was a constant steady
advance in scientific knowledge of the laws of electricity and in their
practical applications, and as soon as some of these rotten, mushroom
companies had been wiped out of existence, they might hope that real
practical progress would be made, and that the day was not far distant
when the public would again acquire confidence in electrical enterprise.
They would then enable inventors and practical men to carry out their
experiments, and to put electrical matters on a proper footing.

* * * * *


Electric lighting dates back, as well known; to the celebrated
experiment of Sir Humphry Davy, which took place in 1809 or 1810, but
the date of which is often given as 1813. There exist however, some
indications that experiments on the production of the electric spark
between carbons had been performed before the above named date.

Mr. S.P. Thompson has given the following interesting details in regard
to this subject: In looking over an old volume of the _Journal de
Paris_, says he, I found under date of the 22d Ventose, year X.
(March 12, 1802), the following passage, which evidently refers to an
exhibition of the electric arc:

"Citizen Robertson, the inventor of the phantasmagoria (magic lantern),
is at present performing some interesting experiments that must
doubtless advance our knowledge concerning galvanism. He has just
mounted metallic piles to the number of 2,500 zinc plates and as many of
rosette copper. We shall forthwith speak of his results, as well as of a
new experiment that he performed yesterday with two glowing carbons.


"The first having been placed at the base of a column of 120 zinc and
silver elements, and the second communicating with the apex of the pile,
they gave at the moment they were united a brilliant spark of an extreme
whiteness that was seen by the entire society. Citizen Robertson will
repeat this experiment on the 25th."

The date generally given for the invention of the electric light by Sir
Humphry Davy is 1809, but previous mentions of his experiment are
found in Cuthberson's "Electricity" (1807) and in other works. In the
_Philosophical Magazine_, vol. ix., p. 219, under date of Feb. 1, 1801,
in a memoir by Mr. H. Moyes, of Edinburgh, relative to experiments made
with the pile, we find the following passage:

"When the column in question had reached the height of its power, its
sparks were seen by daylight, even when they were made to jump with a
piece of carbon held in the hand."


In the _Journal of the Royal Institution_, vol. i. (1802), Davy
describes (p. 106) a few experiments made with the pile, and says:

"When, instead of metals, pieces of well calcined carbon were employed,
the spark was still larger and of a clear white."

On page 214 he describes and figures an apparatus for taking the
galvano-electric spark into fluid and aeriform substances. This
apparatus consisted of a glass tube open at the top, and having at the
side a tube through which passed a wire that terminated in a carbon.
Another wire, likewise terminating in carbon, traversed the bottom and
was cemented in a vertical position.

But all these indications are posterior to a letter printed in
_Nicholson's Journal_, in October, 1800, p. 150, and entitled:
"Additional Experiments on Galvanic Electricity in a Letter to Mr.
Nicholson." The letter is dated Dowry Square, Hotwells, September 22,
1800, and is signed by Humphry Davy, who at this epoch was assistant to
Dr. Beddoes at the Philosophical Institution of Bristol. It begins thus:

"Sir: The first experimenters in animal electricity remarked the
property that well calcined carbon has of conducting ordinary galvanic
action. I have found that this substance possesses the same properties
as metallic bodies for the production of the spark, when it is used for
establishing a communication between the extremities of Signor Volta's

In none of these extracts, however, do we find anything that has
reference to the properties of the arc as a continuous, luminous spark.
It was in his subsequent researches that Davy made known its properties.
It will be seen, however, that the electric light had attracted
attention before its special property of continuity had been observed.

It results from these facts that Robertson's experiment was in no wise
anterior to that of Davy. The inventor of the phantasmagoria did not
obtain the arc, properly so called, with its characteristic continuity,
but merely produced a spark between two carbons--an experiment that had
already been made known by Davy in 1800. The latter had then at his
disposal nothing but a relatively weak pile, and it is very natural
that, under such circumstances, he produced a spark without observing
its properties as a light producer.

It was only in 1808 that he was in a position to operate upon a larger
scale. At this epoch a group of men who were interested in the progress
of science subscribed the necessary funds for the construction of a
large battery designed for the laboratory of the Royal Institution. This
pile was composed of 2,000 elements mounted in two hundred porcelain
troughs, one of which is still to be seen at the Royal Institution. The
zinc plates of these elements were each of them 32 inches square, and
formed altogether a surface of 80 square meters. It was with this
powerful battery that Davy, in 1810, performed the experiment on the
voltaic arc before the members of the Royal Institution.

The carbons employed were rods of charcoal, and were rapidly used up
in burning in the air. So in order to give longer duration to his
experiment, Davy was obliged, on repeating it, to inclose the carbons in
a glass globe like that used in the apparatus called the electric egg.
The accompanying figure represents the experiment made under this form
in the great ampitheater of the Royal Institution at London.--_La
Lumiere Electrique_.

* * * * *



All those who are acquainted with the cable-lifting branch of submarine
telegraphy are well aware how important a matter it is in grappling
to be certain of the instant the cable is hooked. This importance
increases, of course, with the age and consequent weakness of the
material, as the injury caused by dragging a cable along the bottom is
obviously very great.


It is easy also to understand the fact that in nearly all cases the most
delicate dynamometers must fail to indicate immediately the presence
of the cable on the grapnel, more especially in those cases where a
considerable amount of slack grapnel rope is paid out. In many cases,
therefore, the grapnel will travel through a cable without the
slightest indication (or at least reliable indication) occurring on the
dynamometer, and perhaps several miles beyond the line of cable will be
dragged over, either fruitlessly, or to the peril of neighboring cables;
whereas, should the engineer be advised of the cable's presence on the
grapnel, the break will probably be avoided and the cable lifted; at any
rate, the position of the cable will be an assured thing.

My own knowledge of cable grappling has convinced me of these facts; and
I am well assured that those engineers at least who have been engaged
in grappling for cables in great depths, or for weak cables in shallow
water, will heartily agree with me.

In addition to the foregoing remarks re the insufficiency of the
dynamometer as an instrument for indicating the presence of a cable on
the grapnel, I might remind engineers of the troubles and perplexities
which occur incessantly in dragging over a rocky bottom. The grapnel
hooks a rock, a large increase of strain is indicated on the
dynamometer, and it becomes doubtful whether the cable as well is hooked
or not. Again, it frequently happens in grappling over a rocky bottom
that one or more prongs are broken off, the grapnel thus becoming
useless, great waste of time being thus occasioned. Fully realizing all
the difficulties herein enumerated, it occurred to me that a grapnel
might be constructed in such a manner as to automatically signal by
electrical means the hooking of the cable, while it would ignore all
strain that external causes might bring to bear on it, and thereby
obviate the uncertainties attached to the use of the grapnels at present
in vogue. To effect this, I designed early in 1881 a grapnel fitted in
each prong with an insulated conducting surface, and a plunger and pin
so arranged that the cable, when hooked, should, by the pressure that
it would bring to bear on any of the plungers, cause the pin to come in
contact with the conducting surface, itself in electrical communication
with any suitable current detecter and battery on board the repairing
ship, and thereby complete the circuit. This grapnel was successfully
used on the Anglo-American Telegraph Company's repairing steamer Minia
in the summer of 1881.

Subsequently, in discussing the construction of the grapnel with
Captain Troot, we concluded that something was yet wanted to render
the successful working in deep water absolutely sure, and we decided,
consequently, to make certain alterations.

This improved form may be constructed, either with a contact-plate in
each prong, or with one contact-plate common to all the prongs; the
latter is somewhat simpler, and is therefore the plan that we usually
adopt. Both forms are shown in the accompanying diagrams. The form
of grapnel in Diagram No. 1 has one advantage over the other in this
respect, viz., that should a prong be ruptured so as to render it
useless, the fact would immediately be known on board. A circuit formed
in such a manner, by the breaking off of a branch lead, would have
greater resistance than that formed by the contact resulting from
pressure of cable on the plungers; this difference would be manifested
on the indicator (of low resistance) placed in circuit with the
alarm-bell, or, if any doubt remained, a Wheatstone's bridge, or simpler
still, a telephone might be made use of.

In some cases we may protect the plungers from the pressure of ooze,
etc., by guards fitted to the stem of the grapnel, but in practice we
have not found these to be necessary.

The water is allowed free access around and about each separate part, in
order that its pressure shall be equal on all sides. This arrangement
renders the grapnel as effectual in the deepest as in the shallowest

By making the plungers in two pieces, with a rubber washer or its
equivalent between them, we prevent mud or ooze from getting behind and
interfering with their working. As the hole in the rubber surrounding
the contact-plate, by caused the passage of the pin through it, closes
up as soon as the pressure is removed, leaving in the rubber a fault of
exceedingly high resistance, the rubber does not require renewing.

In the rubber in which we embedded the contact-plate, we place a layer
or more of tinfoil or other easily pierced conducting surface, through
which the pin passes on its way to the contact-plate proper. This method
we have adopted in order to make the assurance of contact doubly sure.

The grapnel just described we had in use on the Minia since April last.
We have tried it severely, and have never known it to fail. No swivel
has been used with the rope, in the heart of which is the insulated
wire, as it would allow the grapnel to turn over on the bottom, and
would be apt to twist and break the wire short off. As a matter of
fact, the grapnel will turn, and does turn, with the rope; a swivel is
therefore of no value. We are perfectly awake, however, to the fact that
a grappling-rope should be made in a manner that will not allow it to
kink; and engineers should avail themselves of such rope, especially in
deep water. Patents have lately been granted to Messrs. Trott &
Hamilton for the invention of a form of rope or cable answering all the
requirements of this work.

A small type of grapnel fitted in the manner I have described may be
very advantageously used for searching purposes, to ascertain the
position either of telegraph or torpedo lines; by towing at a quick rate
much time may be saved. The position being ascertained, if it be not
desired to lift the cable, the grapnel can be released and hove on board
by a tripping line, which can always be attached when such work is
contemplated. The great importance of being able to localize an enemy's
torpedo lines without raising an alarm will be readily seen by engineers
engaged in torpedo work.


a, stem of the grapnel containing core; b, flukes; c, recess for
insulated contact-plate connected to core; d, covering plate screwed on
bottom of grapnel; e, button of plug; f, rubber washer and button; g,
metal-plate; h, stem of plug, on which in the under counter-sink, U is
a small metal disk which prevents the fittings from fallings out; i,
needle; j, spring; k, counter-sink for head of plug; l, counter-sink for

* * * * *


A new magnetic balance has been described before the Royal Society
by Prof. D. E. Hughes, F.R.S., which he has devised in the course of
carrying out his researches on the differences between different kinds
of iron and steel. The instrument is thus described in the _Proceedings
of the Royal Society_:

"It consists of a delicate silk-fiber-suspended magnetic needle, 5 cm.
in length, its pointer resting near an index having a single fine black
line or mark for its zero, the movement of the needle on the other
side of zero being limited to 5 mm. by means of two ivory stops or


When the north end of the needle and its index zero are north, the
needle rests at its index zero, but the slightest external influence,
such as a piece of iron 1 mm. in diameter 10 cm. distant, deflects the
needle to the right or left according to the polarity of its magnetism,
and with a force proportional to its power. If we place on the opposite
side of the needle at the same distance a wire possessing similar
polarity and force, the two are equal, and the needle returns to zero;
and if we know the magnetic value required to produce a balance, we know
the value of both. In order to balance any wire or piece of iron placed
in a position east and west, a magnetic compensator is used, consisting
of a powerful bar magnet free to revolve upon a central pivot placed
at a distance of 30 or more cm., so as to be able to obtain delicate
observations. This turns upon an index, the degrees of which are
marked for equal degrees of magnetic action upon the needle. A coil of
insulated wire, through which a feeble electric current is passing,
magnetizes the piece of iron under observation, but, as the coil itself
would act upon the needle, this is balanced by an equal and opposing
coil on the opposite side, and we are thus enabled to observe the
magnetism due to the iron alone. A reversing key, resistance coils, and
a Daniell cell are required."

The general design of the instrument, as shown in a somewhat crude form
when first exhibited, is given in the figure, where A is the magnetizing
coil within which the sample of iron or steel wire to be tested is
placed, B the suspended needle, C the compensating coil, and M the
magnet used as a compensator, having a scale beneath it divided into
quarter degrees.

The idea of employing a magnet as compensator in a magnetic balance is
not new, this disposition having been used by Prof. Von Feilitzsch in
1856 in his researches on the magnetizing influence of the current. In
Von Feilitzsch's balance, however, the compensating magnet was placed
end on to the needle, and its directive action was diminished at will,
not by turning it round on its center, but by shifting it to a greater
distance along a linear scale below it. The form now given by Hughes to
the balance is one of so great compactness and convenience that it
will probably prove a most acceptable addition to the resources of the
physical laboratory.--_Nature_.

* * * * *


Cast iron may be hardened as follows: Heat the iron to a cherry red,
then sprinkle on it cyanide of potassium and heat to a little above red,
then dip. The end of a rod that had been treated in this way could not
be cut with a file. Upon breaking off a piece about one-half an inch
long, it was found that the hardening had penetrated to the interior,
upon which the file made no more impression than upon the surface. The
same salt may be used to caseharden wrought iron.

* * * * *


The accompanying engraving shows a form of Thomson's double bridge, as
modified by Kirchhoff and Hausemann. The chief advantage claimed for
this instrument consists in the fact that all resistances of defective
contact between the piece to be measured and the battery are entirely
eliminated--an object of prime importance in measuring very small
resistances. By the use of this instrument resistances can be measured
accurately down to one-millionth of a Siemens unit.

The general arrangement of the instrument is shown in Fig. 1; Fig. 2
being a diagram of the electrical connections.


The piece of metal to be measured, M, is placed in the measuring forks,
gg, in such a manner that the movable fork is removed as far as possible
from the stationary one; if the weight of the piece be insufficient to
secure a good connection, additional weights may be placed upon it. The
main circuit includes the battery, B (Fig. 2), consisting of from two to
four Bunsen cells, the key, T, the German silver measuring wire, N, and
the piece of metal resting on the forks, all being joined in series. The
German silver wire, N, is traversed by two movable knife-edge contacts,
cc, as shown. Connections are made between these contacts, cc, the
resistance box, the prongs, k and l, of the forks, gg, and the
reflecting galvanometer, as shown in Fig. 2. A resistance of ten units
is inserted at o and n, while at m and p twenty units or one thousand
units are inserted. The positions of cc are then varied until the
galvanometer shows no deflection when the key, T, is depressed.


When such is the case, the ratio of resistances n/m is equal to o/p;
letting M equal the resistance of the metal bar between the points, h
and i, and N equal to the resistance between the points, cc, on the
measuring wire, N, then we shall have

M = N (n/m) = N (o/p).

Knowing the cross section in millimeters, Q, of the bar, and observing
the temperature, t, in degrees Centigrade, its conductivity, x, as
compared with mercury can be determined. If L be the distance, h l or k
i, in meters, then

x = (1/m) (L/Q) (1 + at).

For pure metals the value of a may be taken at 0.004; but alloys have a
different coefficient. The instrument is made by Siemens and Halske,
and is accompanied by a table giving resistances per millimeter of the
measuring wire, N.--_Zeitsch. fuer Elektrotechnik_.

* * * * *


[Footnote: For a full account of experiments relating to magnetism on
railways in New York city, see SCIENTIFIC AMERICAN, January 19,1884.]

_To the Editor of the Scientific American_:

An item has appeared recently in several papers, stating that New York
is a highly magnetized city--that the elevated railroad, Brooklyn Bridge
cables, etc., are all highly magnetized. As this might convey to the
general reader the impression that the magnetism thus exhibited was
peculiar to New York city, and as many of your subscribers look
anxiously for your answers to numerous questions put for the elucidation
of apparent, scientific mysteries, I have thought that perhaps a
statement in plain language of experiments made at various times, to
elucidate this subject, might, in conjunction with a diagram, serve to
explain even to those who have not made a special study of science a few
of the interesting phenomena connected with


Some of the first experiments I made, while professor at the Indiana
State University, were detailed in the March and August numbers,
1872, of the _Journal_ of the Franklin Institute, and I think showed
conclusively that the earth, by induction, renders all articles of iron,
steel, or tinned iron magnetic; possessing for the time being polarity,
after they have been in a settled position for a short time.

In Dr. I. C. Draper's "Year Book of Nature" for 1873, mention is made
of the experiments in which I found every rail of a N. and S. railroad
exhibiting polarity.

The same statements were repeated in one of a series of articles sent by
me to the _Indianapolis Daily Journal_, dated Jan. 20, 1877, in which I
used the following language:

"Every article of iron or steel or tinned iron, by the earth's
induction, becomes magnetic. Thus, if we examine our stoves, or a
doorlock, or long vertical hinge, or even a high tin cup, by holding a
delicate magnetic needle in the hand near those objects, we find the
earth has, by induction, attracted to the lower end of the stove
utensils, etc., the opposite magnetism from its own; and repelled to the
upper end of the stove, etc., the same magnetism which exists in our
northern hemisphere. Consequently, the bottom of the stove, or of the
hinge, cup, etc., will attract the south (or unmarked end) of our
needle; while the top of the stove, etc., attracts the north, or marked
end of our magnetic needle. If we apply our needle to the T rails of a
N. and S. railroad, we not only find that the lower flange of the rail
attracts the S. end of our needle, while the upper flange attracts the
N. end of our needle, but we also find, where the two rails come nearly
together (say within two inches), that the N. end of the rail attracts
the S. end of our needle, while the S. end of the rail attracts the N.
(or marked) end of our magnetic needle."


Quite recently, being anxious to see the effect produced on the needle
by rails laid E. and W., I experimented on some recently laid here;
starting from a S. terminus, in the town of New Harmony, and gradually
curving northeast, until the road pursues a due east course to
Evansville. There is, however, a branch road of about half a mile, which
starts from the Wabash River, at a _west_ terminus, and runs due east
to join the other, near where that main track commences its northeast
curve. The results (more readily understood by an inspection of the
diagram) were as follows:

1. At the south terminus of the railroad, the rails on the east side of
the track as well as those on the west side attracted at their south
ends the marked end of a small magnetic needle, both at the upper and
lower flange; the usual vertical induction being in this case overcome
by the greater lateral induction. Whenever, on progressing north, the
rails were at least about two inches apart, the upper flange of the
north end of any rail would attract the unmarked, while the south end
of its neighbor or any other of the north and south laid rails would
attract the marked end.

2. The same results were obtained from rails laid all around the
northeast curve, and even after they had acquired a due west to east
course; showing that each rail acquired the same magnetic polarity which
would be exhibited by any magnetic needle oscillating freely in our
northern hemisphere, dipping also at its north end considerably downward
if suspended at its center of gravity.

3. Applying the needle at the _west_ terminus, a few anomalies were
observed; but, especially nearer the junction, the rails all gave the
normal result found on the main track.

4. The wheels of the cars standing on the north and south track followed
the same law, exhibiting both vertical and lateral induction, so that
the lower rims and the forward or north part of the periphery attracted
the unmarked end of the needle, while the upper and rear, or south
portions of the periphery of the wheel attracted the marked end.

5. The wheels of cars standing on the east and west road exhibited
the following modification. The lowest rim of all the wheels, whether
standing on the _north_ rails or on the _south_ rails of said track,
in consequence of vertical induction attracted the unmarked end of the
needle, and the upper rims attracted the marked end of the needle; but
the middle portions of the periphery, both anterior and posterior, of
the wheels standing on the north rail, attracted the unmarked end, while
similar middle portions of wheels standing on south rails attracted the
marked end; in consequence of horizontal induction, the wheels being
connected by iron axles, and thus presenting considerable extension
_across_ the track, viz., from south to north.

Magnetite seems to have acquired its polarity in the same manner,
namely by the earth's induction, when the ore contains a large enough
percentage of pure iron. A large specimen (6 in. long by 31/2 deep and
weighing 51/2 lb.) which I obtained from near Pilot Knob, Missouri,
exhibits polarity, not only at its lateral ends, but also vertically,
as the lower surface attracts the unmarked end of a needle, while the
plane, which evidently occupied the upper surface in its native bed,
attracts the marked end of the needle.

Iron fences invariably exhibit only the polarity by vertical induction;
so also small buckets, bells, etc. But in the case of a bell about 3 ft.
in diameter at its base, and over two feet deep, tapering to about a
foot in diameter at the top, I found that although the top attracted the
marked end of the needle, the bottom attracted the unmarked end of the
needle only around the northerly half of the circumference, while
the southern portion of this lower rim attracted the marked end in
consequence of lateral induction, as in N. and S. rails.

Thus, upon a comparison of all these facts, it would appear that, if
the magnetism induced by the earth is due to so-called currents of
electricity, those currents must be _underneath_ the rails, and must
move from west to east, under the south to north rails, and from south
to north under the west to east laid rails, as indicated by the arrows
in the diagram.

This accords perfectly with what we should theoretically expect, in our
northern hemisphere, if the electricity in the earth's crust is due to
thermo-electrical currents from east to west, namely, from the more
heated to the less heated portion, on any given latitude, while the
earth revolves from west to east; as well as also from electrical
currents trending from tropical to Arctic regions.

As the network of iron rails spreads from year to year more extensively
over our continent, it will be interesting to observe whether or not
any effect is produced, meteorological, agricultural, etc., by this
diffusion of magnetism.

It may further interest some of your readers to have attention called to
facts indicating


The year recently closed furnishes interesting corroborative testimony
of an apparent law regarding the propagation of earthquake movements
_most readily_ along great circles of our globe, as well as evidence
that these seismic movements are frequently transmitted along belts
(approximating to great circles) coincident sometimes with continental
trends, at other times with fissures which emanate in radii at every
30 deg., around the pole of the land hemisphere in Switzerland, as described
in one of my papers, read at the Montreal meeting of the A.A.A.S.

The terms synchronism or synchronous, as here used, are not designed to
imply absolute simultaneity (although that is sometimes the case with
disturbances 180 deg. apart), but are rather intended to indicate the
tendency presented by these phenomena to exhibit this internal activity,
during successive days, weeks, or even months, along a given great
circle of the earth, especially one or more of those connected with the
land center; perhaps most of all along the great circle which forms the
prime vertical, when the center of land is placed at the zenith.

In order to test the above, let us examine the record of the most
prominent earthquakes or volcanic eruptions for the year 1883.

Late in Dec., 1882, and early in Feb., 1883, shocks occurred in New
Hampshire; on Jan. 11, 1883, also at Cairo, Illinois, and about the same
time at Paducah, Ky.; Feb. 27 at Norwich, Conn., and early in Feb. at
Murcia, Spain.

These, by examination of any good globe, will be found on a belt forming
one and the same great circle of the earth.

Late in March and during part of April the volcano of Ometeke in Lake
Nicaragua was active (after being long dormant); Panama, portions of
the U.S. of Colombia, and of Chili; also, in May, Helena, M.T.; and,
in June, Quito (with Cotopaxi active) were all more or less shaken by
earthquakes; and are all found on one belt of a great circle.

The principal record for the remainder of the year comprised:

An earthquake at Tabreez in North Persia, early in May, 1883.

The awful destruction in Ischia, July 29 (with Vesuvius active).

The fearful eruption in the Straits of Sunda, 25th Aug. and later.

Shocks in Sumatra and at Guayaquil, about same date or early in Sept.

Shocks at Dusseldorf, according to a Berlin paper of 5th Sept.

Shocks at Santa Barbara and Los Angeles, early in Sept.

Shocks at Gibraltar and Anatolia in October.

Shocks at Malta, Trieste, and Asia Minor in October.

Azram shaken late in Sept., and great destruction between Scios and

Lastly, the formation of a new island in the Aleutian Archipelago. Date
of outburst, early in October, 1883.

Besides these, there were several other less severe disturbances, the
records of which are chiefly obtained from Nature, and which will-be
referred to below.

If the globe be so placed as to have the land center at the zenith, the
exact position of the new island, near Unnok, will be found under the
brazen meridian, while Agram, Tabreez, Sunda, Sumatra, Quito, and
Guayaquil are all on the prime vertical.

Vesuvius and Hecla were both active early in the year, and they, with
the ever restless Stromboli, are situated on the great circle which
forms with the land center at Mount Rosa, the radius running S. 30 deg. E.,
and which would embrace the chief disturbances up to the middle of the
year, including as we go north Malta, Sicily, Rome, region of the Po,
Bologna, and in the Western Continent, after passing Hecla, Helena in
Montana Territory, reaching in Washington Territory and Oregon the belt
of it. American volcanoes: Mounts Baker, Rainier, St. Helens, Hood, and

Still another seismic belt, starting from the ever active Fogo, and
passing through Teneriffe (at that time erupted), would include the
regions disturbed in Oct. and Nov., namely, Cadiz, Gibraltar, Malaga
(Murcia and Valencia somewhat earlier); it then traversed the center of
land, caused the earthquakes at Olmutz in Moravia, and even tremors felt
at Irkutsk, as the seismic war moved along said great circle to the
volcanic region of S. Japan.

Again, the belt which covers the meridian of land center (about 8 deg.-10 deg.
E. long) covers also the region of a disturbanced area in Norway, as
well as that portion of Algeria, viz., Bona, in which a mountain 800
meters high, Naiba, is gradually sinking out of sight. About 100 geo.
miles E. of Bona is where Graham's Island appeared in the Mediterranean,
and a few months later disappeared in deep water.

Another highly seismic belt extends from the volcanoes of Bourbon, N.
Madagascar, and Abyssinia to Santoria and the oft disturbed Scios,
Smyrna, and Anatolia region; and along the same great circle were shaken
Patra in Greece on the 14th Nov., and Bosnia on the 15th; while shocks
had been felt at Trieste and Muelhouse about the 11th, and at Styria on
the 7th, and disturbances at Dusseldorf in Sept. Finally, on the 28th
Dec. S. Hungary (near the confluence of the Drave with the Danube) was
visited by seismic movements along this same great circle, which passes
through the extinct volcanic region of the Eifel, the oft shaken Comrie
in Perthshire, Scotland, the volcanic Iceland, our National Park with
its thousands of geysers, the cataclysmic region of Salt Lake and the
Wahsatch Mountains (so graphically described by the geologists of the
U.S. Geol. Survey), giving rise in Sept. to the earthquakes of Los
Angeles and Santa Barbara, and finally reaching the volcanic islands of
the Marquesas group.

Thus the seismic efforts of 1883 may be seen to have expended their
force partly along the great backbone of the S. and N. American
Cordillera, but more especially from the center of land E. and W. along
its prime vertical from Sunda to Quito, also southwesterly by the E.
coast of Spain, as well as due S. through Algeria, and S. 30 deg. E. through
Rome, Naples, Sicily, etc. Finally, the autumnal catastrophes at and
near Scios, Anatolia, etc., seem to have been caused by a seismic wave,
propagated along the great circle, which often agitates Janina, and
produces earthquakes at Agram, where this great circle crosses the prime


New Harmony, Ind., 27 Feb., 1884.

* * * * *



By Prof. P. FERRAND.

Up to the present time, the methods employed in the province of Minas
Geraes (Brazil) for obtaining iron permit of manufacturing it direct
from the ore without the intervening process of casting. These methods
are two in number:

1. The _method by cadinhes_ (crucibles), which is the simpler and
requires but little manipulation, but permits of the production of but a
small quantity of metal at a time.

2. The _Italian method_, a variation of the Catalan, which requires
more skill on the part of the workmen and yields more iron than the

As these methods seem to me of interest, from the standpoint of their
simplicity and easy installation, I propose to describe them briefly, in
order to give as faithful and general an _apercu_ as possible of their
application. At present I shall deal with the first one only, the one
called the method by _Cadinhes_.


The province of Minas Geraes ocupies a vast extent in the empire
of Brazil, its superficies being about 900,000 square kilometers,
representing nearly a third of the total surface.

The population is relatively small and is disseminated throughout a much
broken country, where the means of communication are very few. So it is
necessary to succeed in producing what iron is needed by means that are
simple and that require but quickly erected works built of such material
as may be at hand. The iron ore is found in very great abundance in this
region and is very easily mined.

In the center of a mass of quartzites that seem lo constitute the upper
level of the eruptive grounds of the province, there are found strata of
an ore of iron designated as _itabirite_--a mixture of oxide of iron and
quartz. These strata are of great thickness, and have numerous outcrops
that permit of their being worked by quarrying.

These itabirites present themselves under two very distinct aspects and
offer a certain difference in their composition. Some are essentially
friable, and are called by the vulgar name of _jacutingaes_. It is
this variety (which is the one most easily mined) that is principally
consumed in the forges. The others, on the contrary, are compact.
Their exploitation is more difficult, and before putting them into the
furnaces it is necessary to submit them to breakage and screening; so
the use of them is more limited.

The first variety contains less iron and more gangue, but, _per contra_,
possesses much oxide of manganese. The second, on the contrary, is
formed almost wholly of oxide of iron with but little gangue and only
traces of oxide of manganese. The following are analyses of these two
varieties of ore:

_Friable Ore_.

Fe_{2}O_{2}.................................. 84.9
Oxide of manganese........................... 9.2
Water........................................ 1.9
Quartz....................................... 4.1

_Compact Ore_.

Fe_{2}O_{3} and traces of manganese.......... 99.6
Quartz....................................... 1.1

_Situation of the Forges_.--A forge is usually placed on the bank of
a brook, or rather of a torrent, which supplies the fall of water
necessary for the motive power by means of a flume about a hundred
meters in length. In most cases the forge is surrounded on all sides
with a forest which yields the wood necessary for the manufacture of the
charcoal, and is in the vicinity of the iron quarry, so as to reduce the
expense of hauling the ore as much as possible. The neighboring
rocks furnish the foundation stones and stones for the furnaces; the
decomposed schist gives the cement and refractory coating, and the
forest provides the wood necessary for the construction of the road,
sheds, etc. The head of the trip hammer, the anvils, and the tools are
the only objects that it is necessary to procure, and even these
the master of the forge often manufactures in part, after beginning
production with an incomplete set.


_General Arrangement of a Forge_.--A forge usually consists of one or
two furnaces of three or four crucibles (the one shown in plan in Fig.
1 has only one four crucible furnace, A); 1 or 2 two fire reheating
furnaces, B; 1 trip hammer, C, actuated by a hydraulic wheel, D;
2 tromps which drive the wind, one of them, E, into the cadinhes
(crucibles), and the other, F, into the reheating furnace; 2 anvils,
G and H, placed near the furnace, for working delicate pieces; and
finally, the different tools that serve for maneuvering the bloom and
finishing the bars. The charcoal is preserved from rain under a shed, l.
The ore, which is brought in as needed, is dumped in a pile at M, in
the vicinity of the crucibles. The buildings are set back against the
mountain, and the water is led in by a double flume, L and N, made of
planks, and empties on one side into the wheel and into the tromp, F,
and on the other into the tromp, E, and then runs into a double waste
channel, P and Q, which carries it to the stream.

[Illustration: FIG 2.--FOUR-CRUCIBLE FURNACE; (PLAN).]

_Four Crucible Furnace_ (Fig. 2).--The arrangement of a furnace is very
simple. It consists of a cube of masonry containing several cylindrical
apertures with elliptic bases, whose large axis is paralleled with the
smaller side of the masonry. This form recalls that of a crucible;
and these cavities are, moreover, so named. In the front part of each
cadinhe there is a rectangular aperture that gives access to the bottom
of the crucible and facilitates the removal of the bloom therefrom. At
the back part there is a small aperture for the introduction of the
tuyere, and which permits, besides, of the nozzle of the latter being
easily got at so as to see whether the blast is working properly.

The sides of the crucibles are covered with a thin layer of refractory
clay, and their bottoms have a spherical concavity to hold the bloom.
The tuyere, which is fitted to a wooden conduit of square section
that runs along the back of the masonry, is placed in the axis of the
cadinhes and enters the masonry at a few centimeters from the bottom
in such away that its nozzle comes just flush with the surface of the
refractory lining. This arrangement prevents the tuyere from getting
befouled by scoriae during the operation of the furnace and thus
interfering with the wind.

_Tromp_.--The tromp which furnishes the necessary wind to the cadinhes
consists of a hollow wooden conduit, a (Fig. 3), of square section,
which enters a chamber, b, along a length of 0.1 m. This conduit, which
is about 7 meters in height, receives the water from the flume through
the intermedium of an ajutage of pyramidal form, which serves to choke
the vein of liquid, and the extremity of which is at a few centimeters
from the conduit in order to facilitate the entrance of the air; the
latter being attracted by an ill defined action that is supposed to
be due to its being carried along by the water, and to a depression
produced by choking the flow of the liquid.

[Illustration: FIG. 3.--THE TROMP.]

Since the air that is sucked in during the operation has constantly same
pressure, there is no valve for regulating the entrance of the water
into the vertical conduit. Upon issuing from the latter, the mixture of
air and water strikes the surface of the water in the chamber, b,
and the violence of the shock upon the bottom is deadened by the
interposition of a stone. While the water is escaping through a lateral
aperture in the chamber, b, the air is reaching the tuyeres through a
wooden conduit of square section which is fitted to an aperture in the
upper part of the chamber. This sorry arrangement, which obliges the
mixture of air and water to penetrate the water at the bottom of the
upright conduit, a, retards the separation of the two fluids, and
results in damp air being forced into the crucibles.

_The Trip Hammer_.--Fig. 4 shows the general arrangement of the
apparatus that go to make up the forging mill. The hammer and cam shaft
have their axes parallel, and the latter is placed in the prolongation
of the axis of the wheel. The hammer consists of a roughly squared beam,
4 meters in length, and of 0.25 m. section. The head, A, consists of a
mass of iron weighing 150 kilos, including the weight of the straps
that surround the beam on every side of the piece of iron. The axis of
rotation is situated at the other extremity of the beam, B. The cam
shaft which serves to maneuver the trip hammer is provided with four
cams which lift the beam at a point near the hammer. The length of this
shaft (to the extremity of which is adapted the water wheel) is 4.75 m.,
and its diameter is 0.50 m. The wheel is an _overshot_ one, 3.25 m. in
diameter by 1 m. in width. The water, which is led to it by a flume,
acts upon it by its weight and impact, and is retained in the buckets
and kept from overshooting the mark by a jacket made of planks.

[Illustration: FIG. 4.--THE TRIP HAMMER.]

The anvil upon which the hammer strikes is surrounded by a bed of stones
(quartzites) derived from the neighboring rocks. It is a mass of iron,
75 kilogrammes in weight. In order to prevent vibrations in the trip
hammer when it is lifted, and increase the number of blows, there is
established a spring beam, which is formed of unsquared timber, which
is firmly fastened at one of its extremities, and which receives at the
other end the shock of the hammer head when the latter reaches the end
of its upward travel.

_Reheating Furnace_.--This is a double fire furnace, like those used in
our smithies, except that the wind, instead of being forced into it by
means of a bellows, is supplied by a tromp which receives water from the
same channel as the wheel. The two furnace tuyeres are arranged exactly
like those of the cadinhes, upon a wooden conduit which starts from the
wind chamber (Fig. 5). This furnace serves to prevent the cooling of
such blooms as are awaiting their turn to be shingled, and of such bars
of finished iron as are being made into tools.


A forge like the one whose plan we give, may be run with 1 workman at
the cadinhes, 1 assistant, 1 workman at the hammer; total, 3 men.

_Furnace_.--The work lasts about twelve hours per day, and three
operations of three to four hours are performed in each cadinhe, thus
making twelve per day. At each operation, 22.5 kilos. of ore and 45 of
charcoal are used. From this there is obtained a bloom of 15 kilos. The
operation is performed as follows:

While the assistant has gone to put the bloom of the preceding operation
under the hammer, the workman prepares at the bottom of the crucible a
bed consisting of a mixture of sand and very fine charcoal, and then
fills the crucible up to its edge with charcoal. At the end of a quarter
of an hour, the fuel being thoroughly aglow, the workman puts in the
first charge of ore in powder (_jacutingue_), about 2 kilos, and covers
it with charcoal.

Starting from this moment, he goes on charging every five or ten minutes
with 1.5 to 2 kilos of ore, taking care in doing so to keep the crucible
stuffed with charcoal, which the assistant places in piles around each
cadinhe. This lasts about two and one-half hours. At the end of this
time he stops putting in charcoal, and standing upon the masonry, walks
from one cadinhe to another, carrying a large rod, in order to study the
lay of the bloom. Then, the fire being entirely out, he scrapes out the
bed of sand and charcoal that closes the opening in the bottom of the
crucible, removes the mass of ferruginous scoriae which forms a hard
paste and surrounds the bloom, and takes this latter out by means of a

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