Scientific American Supplement No. 822 by Various

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SCIENTIFIC AMERICAN SUPPLEMENT NO. 822

NEW YORK, October 3, 1891

Scientific American Supplement. Vol. XXXII, No. 822.

Scientific American established 1845

Scientific American Supplement, $5 a year.

Scientific American and Supplement, $7 a year.

* * * * *

TABLE OF CONTENTS.

I. ANTHROPOLOGY.--The Study of Mankind.--A review of Prof.
Max Muller's recent address before the British Association. 13141

II. CHEMISTRY.--Standards and Methods for the Polarimetric
Estimation of Sugars.--A U.S. internal revenue report on
the titular subject.--2 illustrations. 13138

The Formation of Starch in Leaves.--An interesting
examination into the physiological _role_ of leaves.--1
illustration. 13138

The Water Molecule.--By A. GANSWINDT.--A very interesting
contribution to structural chemistry. 13137

III. CIVIL ENGINEERING.--Demolition of Rocks under Water
without Explosives.--Lobnitz System.--By EDWARD S.
CRAWLEY.--A method of removing rocks by combined
dredging and ramming as applied on the Suez Canal.--3
illustrations. 13128

IV. ELECTRICITY.--Electrical Standards.--The English Board of
Trade commission's standards of electrical measurements. 13129

The London-Paris Telephone.--By W.H. PREECE,
F.R.S.--Details of the telephone between London and
Paris and its remarkable success.--6 illustrations. 13131

The Manufacture of Phosphorus by Electricity.--A new
industry based on dynamic electricity.--Full details. 13132

The Two or Three Phase Alternating Current Systems.--By
CARL HERING.--A new industrial development in electricity
fully described and graphically developed.--15
illustrations. 13130

V. GEOGRAPHY AND EXPLORATION.--The Grand Falls of
Labrador.--The Bowdoin College exploring expedition and
its adventures and discoveries in Labrador. 13140

VI. MECHANICAL ENGINEERING.--Improved Changeable Speed
Gearing.--An ingenious method of obtaining different speeds
at will from a single driving shaft.--2 illustrations. 13129

Progress in Engineering.--Notes on the progress of the last
decade. 13129

VII. MEDICINE AND HYGIENE.--Eyesight.--Its Care during Infancy
and Youth.--By L. WEBSTER FOX, M.D.--A very timely
article on the preservation of sight and its deterioration
among civilized people. 13135

The Use of Compressed Air in Conjunction with Medicinal
Solutions in the Treatment of Nervous and Mental
Affections.--By J. LEONARD CORNING.--The enhancement of
the effects of remedies by subsequent application of
compressed air. 13134

VIII. MINERALOGY.--A Gem-Bearing Granite Vein in Western
Connecticut.--By L.P. GRATACAP.--A most interesting
mineral fissure yielding mica and gems recently opened. 13141

IX. NATURAL HISTORY.--Ants.--By RUTH WARD KAHN.--An
interesting presentation of the economy of ants. 13140

X. NAVAL ENGINEERING.--Armor Plating on Battleships--France
and Great Britain.--A comparison of the protective systems
of the French and English navies.--5 illustrations. 13127

The Redoutable.--An important member of the French
Mediterranean fleet described and illustrated.--1
illustration. 13127

XI. TECHNOLOGY.--New Bleaching Apparatus.--A newly invented
apparatus for bleaching pulp.--2 illustrations. 13133

* * * * *

THE REDOUTABLE.

The central battery and barbette ship Redoutable, illustrated this
week, forms part of the French Mediterranean squadron, and although
launched as early as 1876 is still one of its most powerful ships.
Below are some of the principal dimensions and particulars of this
ironclad:

Length 318 ft. 2 in.
Beam 64 " 8 "
Draught 25 " 6 "
Displacement 9200 tons.
Crew 706 officers and men.

[Illustration: THE FRENCH CENTRAL BATTERY IRONCLAD REDOUTABLE.]

The Redoutable is built partly of iron and partly of steel and is
similar in many respects to the ironclads Devastation and Courbet of
the same fleet, although rather smaller. She is completely belted with
14 in. armor, with a 15 in. backing, and has the central battery
armored with plates of 91/2 in. in thickness.

The engines are two in number, horizontal, and of the compound two
cylinder type, developing a horse power of 6,071, which on the trial
trip gave a speed of 14.66 knots per hour. Five hundred and ten tons
of coal are carried in the bunkers, which at a speed of 10 knots
should enable the ship to make a voyage of 2,800 knots. Torpedo
defense netting is fitted, and there are three masts with military
tops carrying Hotchkiss revolver machine guns.

The offensive power of the ship consists of seven breechloading rifled
guns of 27 centimeters (10.63 in.), and weighing 24 tons each, six
breechloading rifled guns of 14 centimeters (5.51 in.), and
quick-firing and machine guns of the Hotchkiss systems. There are in
addition four torpedo discharge tubes, two on each side of the ship.
The positions of the guns are as follows: Four of 27 centimeters in
the central battery, two on each broadside; three 27 centimeter guns
on the upper deck in barbettes, one on each side amidships, and one
aft. The 14 centimeter guns are in various positions on the
broadsides, and the machine guns are fitted on deck, on the bridges,
and in the military tops, four of them also being mounted on what is
rather a novelty in naval construction, a gallery running round the
outside of the funnel, which was fitted when the ship was under
repairs some months ago.

There are three electric light projectors, one forward on the upper
deck, one on the bridge just forward of the funnel, and one in the
mizzen top.--_Engineering._

* * * * *

ARMOR PLATING ON BATTLESHIPS: FRANCE AND GREAT BRITAIN.

The visit of the French squadron under Admiral Gervais to England has
revived in many a nautical mind the recollection of that oft-repeated
controversy as to the relative advantages of armored belts and
citadels. Now that a typical French battleship of the belted class has
been brought so prominently to our notice, it may not be considered an
inappropriate season to dwell shortly upon the various idiosyncrasies
of thought which have produced, in our two nations, types of war
vessels differing so materially from each other as to their protective
features. In order to facilitate a study of these features, the
accompanying sketch has been prepared, which shows at a glance the
relative quantities of armored surface that afford protection to the
Nile, the Camperdown, the Marceau, the Royal Sovereign, and the Dupuy
de Lome; the first three of these vessels having been actually present
at the review on the 21st of August and the two others having been
selected as the latest efforts of shipbuilding skill in France and
Great Britain. Nothing but the armored surface in each several class
is shown, the same scale having been adhered to in all cases.

[Illustration: Armored Surface for Various Ships]

Two impressions cannot fail to be made upon our minds, both as to
French and British armor plate disposition. These two impressions, as
regards Great Britain, point to the Royal Sovereign as embodying the
idea of two protected stations with a narrow and partial connecting
belt; and to the Nile as embodying the idea of a vast and absolutely
protected raft. For France, we have the Marceau as representing the
wholly belted type with four disconnected but protected stations; and
the Dupuy de Lome, in which the armor plating is thinned out to a
substance of only 4 in., so as entirely to cover the sides of the
vessel down to 5 ft, below the water line; this thickness of plating
being regarded as sufficient to break up upon its surface the dreaded
melinite or guncotton shell, but permitting the passage of
armor-piercing projectiles right through from side to side; provision
being made to prevent damage from these latter to engines and vitals
by means of double-armored decks below, with a belt of cellulose
between them. Thus, as we have explained, two prominent ideas are
present in the disposition of armor upon the battleships of Great
Britain, as well as in that of the battleships of France. But, while
in our country these two ideas follow one another in the natural
sequence of development, from the Inflexible to the Royal Sovereign,
the citadel being gradually extended into two redoubts, and space
being left between the redoubts for an auxiliary battery--this latter
being, however, singularly placed above the armored belt, and _not
within its shelter_--in France, on the other hand, we find the second
idea to be a new departure altogether in armored protection, or rather
to be a return to the original thought which produced the Gloire and
vessels of her class. In point of fact, while we have always clung to
the armored citadel, France has discarded the belt altogether, and
gone in for speed and light armor, as well as for a much lighter class
of armament. Time alone, and the circumstances of actual warfare, can
prove which nation has adopted the wisest alternative.

A glance at the engraving will show the striking contrast between the
existing service types as to armored surface. The Marceau appears
absolutely naked by the side of the solidly armed citadel of the Nile.
The contrast between the future types will be, of course, still more
striking, for the reasons given in the last paragraph. But while
remarking upon the paucity of heavy plating as exhibited in the
service French battleships, we would say one word for the angle at
which it is placed. The receding sides of the great vessels of France
give two very important attributes in their favor. In the first place,
a much broader platform at the water line is afforded to secure
steadiness of the ship and stable equilibrium, and the angle at which
the armor rests is so great as to present a very oblique surface to
the impact of projectiles. The trajectory of modern rifled guns is so
exceedingly flat that the angle of descent of the shot or shell is
practically _nil_. Were the sides of the Royal Sovereign to fall back
like those of the Marceau or Magenta, we seriously doubt whether any
projectile, however pointed, would effect penetration at all. We
conclude, then, that a comparison of the Marceau with the Nile as
regards protective features is so incontestably in favor of the
latter, that they cannot be classed together for a moment. In speed,
moreover, though this is not a point under consideration, the Nile has
the advantage. It is impossible, however, to avoid the conviction that
the Dupuy de Lome would be a most powerful and disagreeable enemy for
either of the eight great ironclads of Great Britain now building to
encounter on service. The Hood and Royal Sovereign have many
vulnerable points. At any position outside of the dark and light
colored portions of armor plate indicated in our drawing, they could
be hulled with impunity with the lightest weapons. It is true that gun
detachments and ammunition will be secure within the internal
"crinolines," but how about the other men and _materiel_ between
decks? Now, the Dupuy de Lome may be riddled through and through bf a
131/2 in. shell if a Royal Sovereign ever succeeds in catching her; but
from lighter weapons her between decks is almost secure. We cannot
help feeling a sneaking admiration for the great French cruising
battleship, with her 6,300 tons and 14,000 horse power, giving an easy
speed of 20 knots in almost any weather, and protected by a complete 4
in. steel panoply, which will explode the shells of most of our
secondary batteries on impact, or prevent their penetration. In fact,
there is little doubt that the interior of the Trafalgar, whether as
regards the secondary batteries or the unarmored ends, would be
probably found to be a safer and pleasanter situation, in the event of
action with a Dupuy de Lome, than either of the naked batteries or the
upper works of the Royal Sovereign. This is what Sir E.J. Reed was so
anxious to point out at the meeting of naval architects in 1889, when
he described the modern British battleship as a "spoiled Trafalgar."
There was perhaps some reason in what he said.--_The Engineer._

* * * * *

DEMOLITION OF ROCKS UNDER WATER WITHOUT EXPLOSIVES-LOBNITZ SYSTEM.[1]

[Footnote 1: Read before the Engineer's Club, Philadelphia. Translated
from _Nouvelles Anodes de la Construction,_ March, 1890.]

By EDWIN S. CRAWLEY.

The methods of demolishing rocks by the use of explosives are always
attended by a certain amount of danger, while at the same time there
is always more or less uncertainty in regard to the final result of
the operation. Especially is this the case when the work must be
carried on without interrupting navigation and in the vicinity of
constructions that may receive injury from the explosions.

Such were the conditions imposed in enlarging the Suez Canal in
certain parts where the ordinary dredges could not be used.

Mr. Henry Lobnitz, engineer at Renfrew, has contrived a new method of
procedure, designed for the purpose of enlarging and deepening the
canal in those parts between the Bitter Lakes and Suez, where it runs
over a rocky bed. It was necessary to execute the work without
interrupting or obstructing traffic on the canal.

The principle of the system consists in producing a shattering of the
rock by the action of a heavy mass let fall from a convenient height,
and acting like a projectile of artillery upon the wall of a fortress.

From experiments made in the quarry of Craigmiller, near Edinburgh,
with a weight of two tons shod with a steel point, it was found that
with a fall of about 5.5 meters (18.04 ft.) there was broken up on an
average more than 0.113 cubic meter (0.148 cubic yard) of hard rock
per blow. The first blow, delivered 90 centimeters (2 ft. 111/2 in.)
from the wall face, produced an almost imperceptible rent, a second or
a third blow applied at the same place extended this opening often to
a length of 1.50 meters (4 ft. 11 in.) and to a depth of from 90 to
120 centimeters (2 ft. 11 in. to 3 ft. 11 in.) The next blow opened
the fissure and detached the block of rock.

The application of the same system under water upon an unknown surface
would obviously modify the conditions of the experiment. Nevertheless,
the results obtained with the "Derocheuse," the first dredging machine
constructed upon this principle, have realized the hopes of the
inventor.

This dredging machine was launched on the Clyde and reached Port Said
in twenty days. It measures 55 meters (180 ft. 5 in.) in length, 12.20
meters (40 ft. 1 in.) in breadth, and 3.65 meters (12 ft.) in depth.
Its mean draught of water is 2.75 meters (9 ft. 21/2 in.) It is divided
into eighteen watertight compartments. Five steel-pointed battering
rams, each of four tons weight, are arranged in line upon each side of
the chain of buckets of the dredging machine. See Figs. 1 and 2. The
battering rams, suspended by chains, are raised by hydraulic power to
a height varying from 1.50 to 6 meters (4 ft. 11 in. to 19 ft. 8 in.),
and are then let fall upon the rock. The mechanism of the battering
rams is carried by a metallic cage which can be moved forward or
backward by the aid of steam as the needs of the work require. A
series of five battering rams gives from 200 to 300 blows per hour.

[Illustration: FIG. 1.--LONGITUDINAL SECTION.]

[Illustration: FIG. 2.--PLAN]

A dredging machine combined with the apparatus just described, raises
the fragments of rock as they are detached from the bottom. A guide
wheel is provided, which supports the chain carrying the buckets, and
thus diminishes the stress upon the axles and bearings. With this
guide wheel or auxiliary drum there is no difficulty in dredging to a
depth of 12 meters (39 ft. 4 in.), while without this accessory it is
difficult to attain a depth of 9 meters (29 ft. 6 in.)

A compound engine, with four cylinders of 200 indicated horse power,
drives, by means of friction gear, the chain, which carries the
buckets. If the buckets happen to strike against the rock, the
friction gear yields until the excess of resistance has disappeared.

Fig. 3 indicates the manner in which the dredge is operated during the
work. It turns alternately about two spuds which are thrust
successively into the bottom and about which the dredge describes a
series of arcs in a zigzag fashion. These spuds are worked by
hydraulic power.

A three ton hand crane is placed upon the bridge for use in making
repairs to the chain which carries the buckets. A six ton steam crane
is placed upon the top of the cage which supports the hydraulic
apparatus for raising the battering rams, thus permitting them to be
easily lifted and replaced.

The dredging machine is also furnished with two screws driven by an
engine of 300 indicated horse power, as well as with two independent
boilers. Two independent series of pumps, with separate connections,
feed the hydraulic lifting apparatus, thus permitting repairs to be
made when necessary, without interrupting the work. A special machine
with three cylinders drives the pumps of the condenser. An accumulator
regulates the hydraulic pressure and serves to raise or lower the
spuds.

At the end of the Suez Canal next to the Red Sea, the bottom consists
of various conglomerates containing gypsum, sandstone and sometimes
shells. It was upon a bed of this nature that the machine was first
put to work. The mean depth of water, originally 8.25 meters (26 ft. 3
in.), was for a long time sufficient for the traffic of the canal; but
as the variations in level of the Red Sea are from 1.8 to 3 meters (5
ft. 11 in. to 9 ft. 10 in.), the depth at the moment of low water is
scarcely adequate for the constantly increasing draught of water of
the steamers. Attempts were made to attack the rocky surface of the
bottom with powerful dredges, but this method was expensive because it
necessitated constant repairs to the dredges.

[Illustration: FIG. 3.--DREDGE MOVEMENT.]

These last, although of good construction, seldom raised more than 153
cubic meters (200 cubic yards) in from eight to fifteen days. Their
daily advance was often only from sixty to ninety centimeters (about 2
to 3 ft.), while with the "Derocheuse" it was possible to advance ten
times as rapidly in dredging to the same depth. The bottom upon which
the machine commenced its work was clean and of a true rocky nature.
It was soon perceived that this conglomerate, rich in gypsum,
possessed too great elasticity for the pointed battering rams to have
their proper effect upon it. Each blow made a hole of from fifteen to
sixty centimeters (6 in. to 2. ft.) in depth. A second blow, given
even very near to the first, formed a similar hole, leaving the bed of
the rock to all appearances intact between the two holes. This result,
due entirely to the special nature of the rock, led to the fear that
the action of the battering rams would be without effect. After some
experimentation it was found that the best results were obtained by
arranging the battering rams very near to the chain of buckets and by
working the dredge and battering rams simultaneously. The advance at
each oscillation was about 90 centimeters (about 3 ft.)

The results obtained were as follows: At first the quantity extracted
varied much from day to day; but at the end of some weeks, on account
of the greater experience of the crew, more regularity was obtained.
The nature of the conglomerate was essentially variable, sometimes
hard and tenacious, like malleable iron, then suddenly changing into
friable masses surrounded by portions more elastic and richer in
gypsum.

During the last five weeks at Port Tewfik, the expense, including the
repairs, was 8,850 francs ($1,770.00) for 1,600 cubic meters (2,093
cubic yards) extracted. This would make the cost 5.52 francs per cubic
meter, or $0.84 per cubic yard, not including the insurance, the
interest and the depreciation of the plant.

After some improvements in details, suggested by practice, the machine
was put in operation at Chalouf upon a hard rock, from 1.50 to 3
meters (4 ft. 11 in. to 9 ft. 10 in.) thick. The battering rams were
given a fall of 1.80 meters (5 ft. 11 in.). To break the rock into
fragments small enough not to be rejected by the buckets of the
dredge, the operations of dredging and of disintegration were carried
on separately, permitting the battering rams to work at a greater
distance from the wall face. The time consumed in thus pulverizing the
rock by repeated blows was naturally found to be increased. It was
found more convenient to use only a single row of battering rams. The
production was from about seven to eleven cubic meters (9.2 to 14.4
cubic yards) per hour. Toward the close of September, after it had
been demonstrated that the "Derocheuse" was capable of accomplishing
with celerity and economy the result for which it was designed, it was
purchased by the Suez Canal Company.

During the month of September, an experiment, the details of which
were carefully noted, extending over a period of sixteen days, gave
the following results:

Crew (33 men), 140 hours. 2,012.50 francs $402.50
Coal, @ 87.50 francs ($7.50) per ton 787.50 francs 157.50
Oil and supplies 220.00 francs 44.00
Fresh water, 16 days 210.00 francs 42.00
Sundries 42.50 francs 8.50
---------------- ---------
Total expense for removing 764
cubic meters (999.2 cubic yards), 3,272.50 francs $654.50

Average, 4.28 francs per cubic meter ($0.65 per cubic yard).

This result cannot be taken as a universal basis, because after a
year's use there are numerous repairs to make to the plant, which
would increase the average net cost. This, besides, does not include
the cost of removal of the dredged material, nor the depreciation, the
interest and the insurance.

It should be added on the other hand, however, that the warm season
was far from being favorable to the energy and perseverance necessary
to carry on successfully experiments of this kind. The temperature,
even at midnight, was often 38 deg. C. (100.4 deg. F.). Still further, the work
was constantly interrupted by the passage of ships through the canal.
On an average not more than forty minutes' work to the hour was
obtained. Notwithstanding this, there were extracted at Chalouf, on an
average, 38.225 cubic meters (50 cubic yards) per day without
interrupting navigation. At Port Tewfik, where there was much less
inconvenience from the passage of ships, the work was carried on from
eight to eleven hours per day and the quantity extracted in this time
was generally more than 76 cubic meters (99.4 cubic yards).

In most cases the system could be simplified. The engine which works
the dredge could, when not thus employed, be used to drive the pumps.
The propelling engine could also be used for the same purpose.

The results obtained at Suez indicate the appreciable advantages
arising from the application of this system to the works of ports,
rivers and canals, and ever, to the work of cutting in the
construction of roads and railroads.

* * * * *

PROGRESS IN ENGINEERING.

Mr. T. Forster Brown, in his address to the Mechanical Science Section
of the British Association, said that great progress had been made in
mechanical science since the British Association met in the
principality of Wales eleven years ago; and some of the results of
that progress were exemplified in our locomotives, and marine
engineering, and in such works as the Severn Tunnel, the Forth and Tay
Bridges, and the Manchester Ship Canal, which was now in progress of
construction. In mining, the progress had been slow, and it was a
remarkable fact that, with the exception of pumping, the machinery in
use in connection with mining operations in Great Britain had not, in
regard to economy, advanced so rapidly as had been the case in our
manufactures and marine. This was probably due, in metalliferous
mining, to the uncertain nature of the mineral deposits not affording
any adequate security to adventurers that the increased cost of
adopting improved appliances would be reimbursed; while in coal
mining, the cheapness of fuel, the large proportion which manual labor
bore to the total cost of producing coal, and the necessity for
producing large outputs with the simplest appliances, explained the
reluctance with which high pressure steam compound engines, and other
modes embracing the most modern and approved types of economizing
power had been adopted. Metalliferous mining, with the exception of
the working of iron ore, was not in a prosperous condition; but in
special localities, where the deposits of minerals were rich and
profitable, progress had been made within a recent period by the
adoption of more economical and efficient machinery, of which the
speaker quoted a number of examples. Reference was also made to the
rapid strides made in the use of electricity as a motive power, and to
the mechanical ventilation of mines by exhaustion of the air.

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