Page images
PDF
EPUB

spindles. The process adopted by the author Such a vessel, he contended, could be constructed was ventilated by means of a copper fan, of large for the detection of sulphur is very simple. on a displacement but little different from that of diameter, suspended horizontally under the deck, He merely digested the oil for some hours at a the "Bellerophon," and it would not only be im- and driven by a small donkey-engine, bolted to gentle heat with a small piece of potassium. penetrable now, but would probably remain so the deck beams. The fan, which was not enThe metal became coated with a reddish crust, for some years. He considered it had been shown, closed in a casing, drew the air, which it sent and there was a slight evolution of hydrogen. by ample experience, that such vessels were sea- into the engine-room, through a pipe or cylin After the digestion water was added, and the worthy, afforded comfortable accommodation for drical trunk, 4ft. in diameter and 8in. thick, the crew, were healthful, and popular with sailors. carried high above the deck. The air thus aqueous solution was tested with nitro-prusside In the common ironclad, as the armour had to forced into the engine-room passed thence into of sodium. The result was a deep purple- be spread over a high side, it was necessarily the boiler-room, to maintain the combustion in coloured solution, which showed the presence thin and weak; whereas in the monitor system, the furnaces, which was also aided by two of a considerable amount of sulphur. On dis- the sides being very low, the area to be protected Dimpfel blowers, each 78in. diameter, applied tilling the oil, the author also obtained sul-was reduced to a minimum, so that with the same under the turret, through the top of which the phurous acid. Dr. Vohl is of opinion that displacement the armour might be made of great air was drawn. The sides of the ship were only when the raw oil is treated with concentrated thickness, such as would be impenetrable by the 16in: above the water line, and were defended sulphuric acid in the refining process, some heaviest existing ordnance. The "Kalamazoo" by armour 6ft. deep and 4ft. thick, 104in. of sulphur compounds are formed which are not class of monitors had side armour 14in. thick this thickness being of iron, and the remainder backed by several feet of oak, and these vessels of oak. The turret was of iron, 24ft. inside removed by the subsequent treatment with an alkali at the ordinary temperature. Paraffin Possessed great facility of evolution, as they diameter, 9ft. 6in, high, and 15in, thick. The were fitted with balanced rudders and twin screws. vessel tapered to a point at each end, the side oils are sometimes bleached by treatment with In both the armour and the guns, the broadside armour being continued so as to form a ram both chlorine and chlorine compounds; and, as system was one of diffusion, the turret or monitor at the stem and at the stern; and by this projec the presence of these in a lubricator would system one of concentration. The former had tion at the stern both the screw and the rudder also be objectionable, Dr. Vohl examined the been adopted in France and in England, the latter were effectually protected. The weight of each oils for them, but obtained only a trace of chlo- in America, where about sixty vessels of this class shot discharged by the 15-inch gun was 425lb. rine in one. Hydrofluoric acid also bleaches had already been built, and recently by Russia and and the quantity of powder burnt every charge parafin oil, and greatly modifies the odour of some other continental powers. In the broadside was 60lb. ita We have never heard of the practical system the only material innovation on the model Comparing the destructive and resisting powers use of this agent, but Dr. Vohl states that he of the old men-of-war was in the application of of such a vessel as the "Dictator" with an iron. has found it in a lubricating and also in a burn-iron armour to the sides. In some cases the clad like the "Bellerophon," the latter carrying armour was not extended to the bow and the on each broadside five guns of 10in. bore, ing oil. In the former it is highly objection- stern, but only the central part of the sides and besides two guns at the bow and three at the able, since the oil quickly attacks metals; and a belt at the water line were protected, and stern of 7in. bore, it was contended that none of in the latter it is no less so, for in the combus-armour bulkheads were carried across the ship, these guns could pierce the iron turret, or low tion it gives rise to the formation of a highly before and behind the protected portions of the sides of the former, or the deck, composed as it irritating vapour, which causes inflammation sides, so as to form the central part of the vessel was of oak planks, 9in, thick, covered with 2in. of the eyes, destroys colours, and acts on into a rectangular fort. This was the principal of iron, and that all the parts of the vessel were glass. on which the "Bellerophon" and other recent equally strong to resist the forces that might be vessels had been built, and its advantage was brought to bear against them. It might be that it enabled thicker armour to be applied. In supposed that the Dictator" would be easily the monitor system, the guns, which were of run down by the "Bellerophon," but this was large calibre, were carried in one or two cylin- argued to be impossible, even if the former were drical towers of iron, and the weight of the broad-stationary, nor did it agree with experience, for side was concentrated in one or two enormous the "Merrimac," when she encountered the first shot, which had momentum enough to go through the armour of any of the broadside vessels of the Royal Navy of Great Britain.

Dorlac and Samimi, in a paper on the manufacture of lime in the Department of Mayenne, assert that chalk parts with its carbonic acid more easily in a current of steam. They state, in fact, that 100 parts of chalk lost in steam 3.1 parts more carbonic acid than in air, and thus produced a stronger lime. Another assertion of the authors is, that chalk increases onetenth in volume when burnt into lime. It is generally stated that a decrease of volume takes place, but the authors seem to have made their experiments very carefully.

There were certain points of dissimilarity between the turret ships of Captain Coles and those of Captain Ericsson, the most material being that the sides were not nearly so low in the former as Dr. Jacobsen gives a very ready test for the in the monitors, and the armour of the sides and detection of rancidity in oils. Dry rosaniline displacement. be made so hick; nor would it be the turrets could not consequently, with any given is completely insoluble in neutral fats; but if possible, wi h safety to reduce the height of the the smallest proportion of a tatty acid is pre-sides, owing to the turrets being carried on rollers sent, the rosaniline dissolves, giving a colour on the lower deck, thus passing through openings in proportion to the amount of the acid present. in the upper deck, which it was difficult to keep The test may also be useful in the examina- tight without jambing the turrets; the openings tion of animal and vegetable oils intended for to the engine-room were also merely covered use as lubricators. with gratings, or were otherwise similarly unprotected. In the monitors, on the contrary, the deck, and all the openings to the interior of the turrets revolved upon a metal ring, on the upper vessel were through the top of the turret, or through shot-proof trunks or pipes, so that even if the deck were washed by the waves, water could not enter the vessel so long as the deck remained watertight. Captain Coles's vessels had been but little tested in actual war, and therefore the objections urged against his system had yet to be proved. On the other hand the monit rs had been found, during a war of unprec magnitude, to be both shotworthy and seaworthy; they were confessedly unequalled in their power of penetrating other vessels and of resisting penetration themselves.

Dr. Wiederhold gives a receipt for a glazing free from lead, and adapted for ordinary pottery, and especially for cooking utensils. It is a mixture of silicate of soda or potash and borate of lime-the ordinary boro-calcite from South America answers. The two have only to be mixed together so as to form a thin paste, and can then be used in the ordinary way. The inventor, we are bound to say, speaks doubtfully of the value of the glaze, but the process deserves a trial.

INSTITUTION OF CIVIL ENGINEERS.
Ta meeting of the above institution held on

[ocr errors]

structure monitor

As an illustration of the main features of the

monitor and tried to run over her, suffered far
more damage from the attempt than her oppo.
nent. It was, however, by the power of the
guns and by the thickness of the armour, that
the issue of the contest would be mainly deter
mined; and while the guns of the "Bellerophon"
would be powerless against the armour of the
"Dictator," even if fired in converging salvos,
armour of her adversary.
the "Dictator's" guns would easily pierce the

The main point connected with the structure of the monitors, which had provoked controversy among naval men, was whether it was possible to make heavy vessels, so low in the water a the monitors were, safe at sea. Even if this should be doubted, the necessity for the employ. ment of monitors for the protection of ports, harbours, and estuaries, was not the less exigent, seaworthiness and height of side were indissolubly But although, in the nautical mind, the ideas of associated, it was believed that it would not be difficult to show that there was no necessary connection between these conditions. In the monitors, the deck was as tight as the bottom, and the only openings to the interior were through towers which the waves could not enter. Moreover, such vessels did rise to the sea, and it was found in practice, that towers of the deight of those of the "Dictator" were quite

Gregory, Esq., vice-president, in the chair, the was given of the American war-steamer "Dic-
paper read was on Ships of War," by Mr. John tator," built by contract under Ericsson. Her
Bourne. The author stated that, in his opinion, length was 314ft., beam 50ft., and draught of
the only vessels capable of carrying sufficient water 20ft., with 800 tons of coals, and when
thickness of armour to resist modern ordnance fully equipped, she was fitted with a single
were those built on the monitor or turret sys- turret, carrying two Rodman guns, each of 15in.
tem, the invention of Captain John Ericsson, of bore; Ericsson maintaining that one turret was
New York. He maintained that, although broad-superior to several. She was propelled by a pair
side vessels might be useful and even necessary, of engines with cylinders 100in. diameter and 4ft.
and he could imagine cases where they might al-stroke. The diameter of the screw was 21ft.
most be indispensable, yet that no broadside fleet 8in., with four blades, and 34ft. pitch. Steam
would be safe unless accompanied by a flotilla of was supplied to the engines by six boilers, with
monitors. It was simply a question of prepon- a double tier of furnaces, numbering fifty-six in
derance of forces; and in any future maritime
war, the strongest armour and the heaviest guns
must necessarily prevail. He proposed that any
monitors now to be built should have side armour
18in. thick backed by 4ft. of oak, and a turret 24in.
thick carrying two 20-inch wrought-iron guns.

all. The heating surface of the boilers was
34,000 square feet, and the grate area 1,120
square feet. The chimney was 10ft. in diameter,
and 8in. thick at the base, and was provided
with a shell-proof grating, placed about 6ft.
above the level of the deck. The engine-room

equate to enable the vessel to encounter with safety the heaviest seas to which any vessel could be subjected. During the two years the monitors were exposed, on a stormy coast, to all kinds of weather, they proved to be both shotworthy and seaworthy, and the healthiest vessels.

of the "Monadnock" round Cape Horn, and of the "Miantonomoh" across the Atlantic, had caused the most plausible of the objections to the system to be abandoned. Various other objections were noticed, as, for instance, the want of liveliness imputed to the monitors, but this it was argued was a material advantage in any vessel requiring to take an aim with heavy guns, since it must make the aim more sure. In conclusion, the author said, what it concerned the Government and the country to know was, that in the Royal Navy there were vessels of at least equal powers in guns and in armour to those possessed by any other nation, so that in the event of a naval war, the broadside fleet might not be disabled or captured, from the want of a flotilla of protecting monitors, whose function it would be to encounter any similar vessels belonging to the enemy.

A

SELF-EXTINGUISHING SAFETY.LAMP.

FEELING has long existed that many lamentable explosions in collieries would be prevented by the exclusive use of a safety-lamp which, whilst affording an abundance of light, should remain securely closed so long as the flame is unextinguished. To obtain an abundance of light, no lamps are equal to those of the Clanny or Mueseler pattern, but in this country there has usually been a great objection to it, owing to the existence of a fear that the glass would get damaged, and deprive the lamp of its advantages, notwithstanding the fact that

scarcely one, if any, instance is known of an explosion caused through the failure of a glass in the whole of Belgium, although the Mueseler lamp has been almost exclusively used there for many years. The recent calamities having caused fresh attention to be directed to the prevention of explosions, the subjoined description of an ingenious self-extinguishing safety. lamp will be generally interest

[blocks in formation]

For a

similar reason the liquid particles adjacent to
these last pass into the solid state at a tempera-
ture still higher; and thus the process continues
until, at last, all the ice formed and the surround-
ing water are raised to the temperature of 32 deg.
Fah. The process of course would terminate
here if the vessel containing the liquid were a
perfect non-conductor of heat, but as this condi
tion is unattainable, the reduced value in water
of the vessel must be found, and this included in
the given quantity of water.

As the consecutive portions of ice are formed
at different temperatures varying according to a
complicated law, which depends on the conduc-
tibility of water, its latent heat, and the
specific heat of ice, the exact determination
of the quantity of ice formed would at first sight
appear to be of considerable difficulty; this diffi-
culty, however, as I shall presently show, is only

ing. The object of the invention, which, says the solid state, this transition takes place at a tem-
Mining Journal, has been patented by Messrs.perature higher than the initial one.
Hall and Cooke, of Birmingham, is to prevent
the miner opening his lamp, as, if he does
attempt it, either the light is extinguished or the
lamp cannot be opened. In the engraving, fig. 1
is the lower part of a Clanny lamp, to which the
invention is best adapted; a is the body, or oil
vessel; b is the body-ring, which is screwed on
the body; this ring has a slot or recess, which is
cut out opposite the extinguisher foot c', in fig. 2.
The extinguisher c is shown down on the wick
in figs. 1 and 3, and when the lamp is required
for use it is trimmed and lighted. The bottom,
or oil vessel, is then taken in the left hand, the
spring d is held back with the thumb, the extin-
guisher is then lifted with the right hand, and
the foot is turned to the position of c, fig. 2. The
lamp is then screwed together, and the small wire
, which passes through the body of the lamp, is
turned towards the foot of the extinguisher, and
pushes it into the slot or recess in the body-ring.
It cannot then be opened without forcing the
extinguisher upon the light; and should anyone
place the pushing or pricker-wire f between the
fame and the extinguisher, the foot of the ex-
tinguisher cannot then pass under the spring d,
and the said spring d is forced into the before-
mentioned recess, and effectually prevents open-
ing until the wire is removed. The same takes
place should the person in charge place the wick
an extra height, so as to retain a flame after the
extinguisher has fallen upon the burner. The
lamps are very little more costly than the ordinary
Clanny lamps.

apparent.

Before proceeding to the consideration of the problem itself I shall establish the following theorem:-If A denote the latent heat of water at the temperature 32 deg.-t, deg., A the latent heat of water at 32 deg. and c the mean specific heat of ice at the temperature 32 deg.- t,

then

[ocr errors]

To prove this, consider one pound weight of water at the temperature 32 deg. t, deg., and sup. pose it (1) converted into ice at the same tempe rature, then (2) raised as ice in temperature to 32 deg., then (3) converted into water at 32 deg., and finally (4) cooled down again as water to 32 deg. — t1 deg., and consequently brought back to its original state. Now since ON THE FREEZING OF WATER AT LOW the quantity of heat latent and sensible in the

TEMPERATURES.*

BY ARTHUR HILL CURTIS, LL.D.

WHEN water which has been reduced in temperature below the ordinary freezing point without becoming solidified is agitated, it is well known that a portion of it becomes frozen; and the question immediately arises, how much? This question has been already answered, and the result arrived at tested by experiment. In obtaining the result, however, it has been assumed that all the ice is formed either at the temperature of 32 deg. Fah., or at the initial temperature of the water. Now a little consideration will show that neither of these assumptions is true. The congelation commences at some one point, or at a certain finite number of points; certain small particles of ice are formed at these certres of congelation, a large quantity of heat is given out by each particle, and as water is a bad conductor of heat, this is principally communicated to the adjacent particles of water, and when immediately after wards these particles pass from the liquid to the

Communicated by the author to the Philosophical

Magazine.

pound of water is the same at the commencement
and end of the process, it is evident that the sum
of the two quantities given out by it in the stages

(1) and (e)) met be in the stages (2) of 103).
communicated to it in the stages (2) and (3).
This consideration at once gives the equation-

[ocr errors]

&c., while W- (91 + 9a +93 + &c.), is heated as
water through t deg., by equating the quantity
of latent heat rendered sensible to the quantity
of heat spent in raising the temperature of the
whole we obtain the following equation :-
A1 91 +λ2 92 + λ3 93+ &c. = t (W
qs — &c.) + 91 (t—t,) + q2 (t—t2) + 93 (t—t3)
+ &c. + ai gi ti + cz q2 t2 + c3 q3 t3 + &o.
Or, substituting for AL, A · (1 — c1) t1, for λ2 A —
(1-c3) t2, and similarly for A3, &c., we obtain
λ (9, +92 +93 + &c.) =tW,

or

[blocks in formation]

The quantity which is here denoted by λ is the
number of units of heat requisite to convert a
pound of ice at the temperature of 32 deg. Fah.
into a pound of water at the same temperature,
the unit of heat being that quantity which is
sufficient to raise the temperature of a pound of
water through 1 deg. Fah. The value of λ,
according to the experiments of Provostaye,
Desains, and Regnault, is 142-65; so that a =
t
If instead of measuring change of tem-
142.65'
perature by the Fahrenheit scale we employ the
Centigrade, and define the unit of heat to be the
quantity of heat requisite to raise a pound of
water through 1 deg. of that scale, we have s =
where deg. denotes the temperature

0

79.25'

of the water in its initial state, as determined by
the Centigrade thermometer. If we adopt the
measure of the latent heat of ice at 32 deg. Fah.,
or zero Centigrade, deduced from the experi
ments of Person, the above expressions will be-
t
come and respectively.
144 80

BOILER EXPLOSIONS NOT ALWAYS
MYSTERIOUS.

T

quency, the readers of our public journals intervals, recurring with terrible freare startled and shocked-if familiarity has not indeed bred callousness-by accounts of steam boiler explosions, attended always with loss of property, and often with loss of life or limb. To no other subject is the old adage, "in too much discussion the truth is lost," more applicable than to that of boiler explosions. The cause of these catastrophes has been so muddled by wordy dissertations, mysterious theories, and senseless conjectures that few think of looking directly at the facts of each individual case and deciding each on its own evidence. Mysterious agencies, ander the names of contraction," "expansion," "electricity," "development of explosive gases," and others, figure conspi. cuously in the reports of committees of inquiry. The causes which are most obvious, or could be most easily ascertained, are overlooked, and the investigators go prowling about among unknown or not understood forces, to find that which fre quently is before their eyes. Braces originally too weak, corroded, or improperly located; plates running longitudinally instead of circum. ferentially; defective riveting; plates weakened

66

by large holes not filled with thpor iron, ciency in the thickness of plate; poor iron, and carelessness in calking, are overlooked, to say firing, or neglected water feed, and incompetent nothing of corrosion from impure water, hard attendants. Sometimes, in riveting, the holes in the plates diverge half their diameter, and they are reamed to a circular form, or enough to admit the ordinary rivet, which cannot fill the space, and depends for its security wholly on the juxta position of the heads with the surface of the plates. Heat expands the iron, loosening the rivets, the water works through, and, if containing salts, oxidises the iron, opening the way for a rupture. The careless use of the calking chisel sometimes cuts into the plate or of its thickness, so that when an explosion occurs the line of the fracture follows the channel thus made, as the breaking of glass follows the dia. mond scratch.

λ1+t1 =λ+c1 t1, or λ1 = λ — (1 — c1) t1. (1) It may be remarked that no assumption is here made about the specific heat of ice being constant for different temperatures; c, t, is, in fact, only a symbol for the entire quantity of heat necessary to raise one pound weight of ice from 32 deg. t, deg. to 32 deg. This being established, I shall now proceed to consider the question proposed. Let W denote the weight in pounds of the given quantity of water inclusive of the containing vessel reduced, 32 deg.—t deg. its temperature, and Q the weight of the ice formed; let q, denote the weight of any particle of ice, ti the temperature at which it was formed, A, A, C being as above; let qa, ta, Aa, ca be similarly related to a second particle, q3, t3, A3, c3, to a third, and so on; then, as qi, q2, &c., are respectively heated as water through t deg. ta deg., &c., and as ice through t, deg., tz deg., only a few months ago, by which a number of t1 deg., t deg.

[blocks in formation]

persons lost their lives. An investigation was had before the coroner's jury, which resulted in a perfect mystification. Yet the cause or causes should have been apparent in several facts which were ascertained. First, that part of the boiler that gave way was so deficient in substance, that, at the maximum working pressure, the iron was strained to nearly its rupturing limit; the factor of safety, instead of being 5 or 6, being hardly above 0. Second, the sheets, instead of being placed circumferentially so that the joints would not be so long in the direction of the length of the cylinder, and so that each would support the adjacent ones, were placed with the long diameter running lengthwise. Third, the calking iron had injured the iron along the seams nearly 20 per cent., and the braces were placed in an improper manner. It can scarcely be contended that this was an exceptional case. It is to be feared that many of our boilers would not stand a thorough scrutiny on these points. Mr. Edward B. Martin, an eminent engineer of Stourbridge, England, recently read before the Institution of Mechanical Engineers a paper which exhibited the following facts:-During the present century there have been 1,045 boiler explosions in England, causing the death of 4,076 persons and injuries to 2,903. Of the 1,045 explosions, 397 were "uncertain" as to cause; 137 were from over-pressure, from the wedging or over-weighting of safety valves, or from other facts of carelessness; 119 from collapse of internal flues; 114 from shortness of water, or from incrustations, and 9 from extraneous causes not immediately connected with the boiler. From these facts Mr. Martin expressed himself as opposed to all ideas of internal detonation, spontaneous generation of explosive gases, or other mysteries. If this is approximately a correct exhibit of the causes of boiler explosions in England, need we look for some mysterious and unknown agency to account for similar occurrences here? It is well known that English mechanics and engineers are held to strict accountability by the laws, much more so than in this country. It may be claimed that the tenacity of American boiler plate is superior, and such extreme caution as is enforced in England is unnecessary here;

AGRICULTURAL CONDITION OF

FRANCE.

As a test of this quality it may be stated that this light can be seen through the flame of coal gas as a white image on a yellow ground; and, as

[ocr errors]

proof-light constancy, the inventor has had a lamp a-light for two weeks night and day, a duration impossible to be attained with lamps of any other kind.

THE Government commission of inquiry into
the condition of agriculture in France has
reported three interesting facts, which are thus
stated in the Star:1. For many years indus-
trial progress has been more rapid than agricul- of the patentee, and is a composite volatile oil,
The pyrogenic oil is made under the direction
tural progress, which has produced the result of free from all glutinous or resinous principles,
drawing to the factories too many arms in pro- inexplosive, and not spontaneously combustible.
portion to those which remain for agricultural It is sufficiently fixed to keep for any length of
labour. 2. The immense development of works time unchanged, and has no excessive imflam-
of luxury at Paris and other great cities has in- mability or corrosive quality. Its elements are
jured the interests of agriculture, in contributing solely carbon and hydrogen in the exact propor-
to the depopulation of the rural districts. 3. tion for evolving by heat a vapour identical in
Agriculture has remained too much a stranger to composition with olefiant gas-the most con-
public instruction; which has had too serious densed and powerful illuminant known. In the
results-there are too few positions of distinction lamp it is elevated by its own ascensional power,
in the agricultural career, and there is an absence converted into gas by self-engendered heat, and
of knowledge and of interest in agricultural sub- projected by its own expansive force through the
jects among the mass of society. The tendency perforations of the burner, giving without a
of the agricultural population to the towns exists chimney a most perfect light. The advantages
in England as well as in France, and can hardly of this system claim to be in superseding the
be a cause of much regret, since machines are use of chimneys, wicks, oxidators, and regulators,
able to supply the place of manual labour in keeping the lamps dry and clean outside, entire
almost every branch of agricultural work. It avoidance of smoke and smell, combined with
would probably be an advantage to French agri- general economy. The very equable heat given
culture to be forced by any motive to introduce by this light has now rendered possible that
machinery. In any event the tendency is not often-abandoned invention, the "incubator,"
likely to cease so long as labour is better paid in Mr. Crook, of Forest Hill, having successfully
the towns. The commission has unquestionably used it for that purpose on an extended scale.
touched the want of the agricultural population This light has been employed for increasing the
in France, as well as elsewhere, in its reference take of fish, and the patentee is now engaged for
to the absence of instruction in farming subjects the London, Brighton, and South Coast Railway
in schools and colleges.
in experiments to light the carriages of that line,
and likewise a portion of the signals also. In
preventing collisions between ships at sea it pro-
mises to be very useful. Several interesting
experiments with this light are pending, the re-
sult of which we shall probably place before

THE PYROGENIC OIL GAS LIGHT.
N the year 1852 Mr. Samuel Holmes introduced
IN
to public notice a peculiar distillate of vola-
tile hydrocarbons, which he called pyrogenic oil,
since sold by him for burning in lamps he sup
plied. The light given by his lamps of that
period being suitable for small purposes only,
he endeavoured to produce a lamp capable of
giving a larger light, so as to extend the use of

our readers.

THE USE OF STEEL FOR BRIDGES
AND SHIPS.

THE

but in this matter as in others it is "better to be his principle to the lighting of ships, railway Board of Trade have issued circulars and

foolishly careful than foolishly careless." We believe that a rigid examination of boilers and a thorough oversight and testing during the process of manufacture, as well as after completion, enforced by legislative penalties, would prevent some, at least, of the destructive explosions which we are too often called upon to deplore. -Scientific American.

THE EIDOSCOPE.

carriages, &o.; and in 1864 he patented further
improvements in these lamps. Having paid
great attention to the subject of lighting, Mr.
Holmes now claims to have overcome most of
the evils attendant on the use of lamps as hereto-
fore constructed. He contends that any lamp
having a chimney is imperfect; that any lamp
requiring machinery for raising the oil is
undesirable, on account of being easilydisordered;
that any light depending on a wick cannot give
a really constant light for six hours; and, finally,

have obtained several replies as to the probable effect of the use of steel in the construction of bridges and ships. The replies generally are favourable to its use, but it is not recommended that the weight of steel employed should be so much reduced as would be due to the proportion in which its tensile strength exceeds that of iron. It is also recommended that further experiments should be made. A certain thickness is no doubt felt to be required to provide for wear and the action of the weather, over that which might be theoretically necessary to withstand the strains

THE eidoscope is among the most recent novel- and liable at any moment to explode is a danger to which the structures may be subjected. The

ties at the Polytechnic Institution, having been introduced there at the last Christmas session by Professor Pepper, to whom, we believe, the contrivance was first suggested by Professor Wheatstone. This ingenious invention can be made a most valuable accessory to the magic lantern, and it is matter of much surprise that such novel and beautiful effects should be obtained by means of a mechanical contrivance of such extreme simplicity. Unlike the kaleidoscope, invented by Sir David Brewster, in 1814, in which symmetrical effects were evolved by reflection from a number of irregularly shaped objects the eidoscope produces geometrical figures of exquisite beauty by a simple revolution of two perforated metal discs on their own axes. As the discs are slowly revolved, new and infinitely varied forms are created, together with the most delicate gradations of tone. It is a remarkable feature that while these changes are in progress, one perforation, and one only, on the upper plate, will be found perfectly coincident with another on the lower, while all the rest are irregular and form different combinations. When, however, for the magic lantern the discs are put into more rapid motion the greatly accelerated velocity, instead of producing geometrical figures, flashing rays of light appear and are projected on the screen with the most extraordinary results. By employing variously coloured dises of glass or other material in connection with the eidoscope the most gorgeous effects of colour may be obtained.

Board of Trade have laid it down as a rule that ous nuisance. How he proposes to remove this the material of a structure, whether this material catalogue of deficiencies will be seen by a be of iron or steel, shall not be subjected to description of his lamp and oil. In all cases a greater strain than five tons per square inch. As reservoir of glass or metal contains the oil; a it is well known, says the Scientific Review, that wide tube closed at the bottom descends nearly steel will bear a much greater tensile strain than to the bottom of the reservoir and displaces a iron, this rule of the Board of Trade operates central column of the oil. Into and through the as a great restriction on the use of steel in bottom of this closed tube is fixed the burner, bridges, &c. The experiments which we at prewhich is a tube of smaller diameter, containing sent possess on the strength of steel are neither a cotton conductor, whereby the oil is raised to sufficiently numerous nor authoritative to fix defi. near the top of the burner. Above this is a gas nitely the number of tons per square inch which chamber, which is perforated with a double row will express as a rule the strains to which steel of holes for the escape of the gas to burn. Now may safely be subjected. It is therefore very de. the heat generated in burning is, by the conduc- sirable that trustworthy experiments on this subtion of the burner tube, constantly carried down-ject should be made, and continued from time to ward, but the current of fresh cold oil constantly rising upward intercepts the descending heat and employs it in its own vaporisation. Thus the whole of the heat generated is used for intensify ing the light, and none of it is allowed to communicate by conduction to the general bulk of oil in the reservoir a condition of twofold advantage, ensuring conservation of heat to increase the quantity of gas, and preservation of a low temperature to the bulk of the oil below, by the perfect detachment of the burner, throughout its whole length, from all connection with the reservoir containing it. The burner, thus increased in vapour-generating power by its isolation and differential action, provides for combustion at the highest possible temperature by projecting horizontally into the air its in gas from two tiers of jets, arranged one above another, each jet falling in the interstice between two jets in the next row, and their The damage done to Plymouth breakwater by the proximity is such as to allow the best proportion late gales is estimated at £40,000. of air between each for producing a white light.

flamed

time, as improvements are made in the manu facture of steel. Above all, uniformity in tensile strength should, if practicable, or, at least, as far as may be practicable, be rigidly enforced on manufacturers. It would be a great boon not only to the engineering profession, but to the public generally, were it possible to ascertain definitely the tensile strength of a specimen of iron or steel with the same facility as the density may be ascer tained, and without the expensive and laborious, and, after all, uncertain, operation of the proving machine. We hope it will not be long before the progress of science will enable us to attain to this result.

The Sand Patch Tunnel on the Pittsburgh and Connelsville Railroad is at last cut through. Its total length is 4,750ft., being 1,000ft. more than the long tunnel on the Pennsylvania Central Railroad through the Alleghanies between Altoona and Cresson. It is intended for a double track, and is 22ft. wide by 19ft, in height.

[subsumed][subsumed][subsumed][subsumed][merged small][graphic][ocr errors][subsumed][subsumed][subsumed][subsumed][merged small][graphic][graphic]

ΜΕ

[ocr errors]
[ocr errors]

been sufficiently reduced is bolted or sifted, while
that which has not been sufficiently reduced
issues at the lower end of the riddle and may be
returned to the mill. They do not in all cases
fit the ring B so as to revolve; for operating on
some substances they prefer it to be fixed or
stationary and ribbed inside.

IMPROVEMENTS IN GRINDING MILLS. reduced to powder, into a pipe L, from which it
the mill drives the substance, after having been
TESSRS. THOMPSON and STATHER, of passes to an inclined cylindrical riddle M, shown
Kingston-upon-Hull, engineers, have just in fig. 4, and also in elevation in fig. 5, through
patented some improvements in mills for grind. the sides of which riddle that portion which has
ing corn and other hard substances, and which
are illustrated in the above engraving. Inside
an outer circular casing or drum, as shown at A
in vertical section in fig. 1, in transverse section
in fig. 2, and in plan in fig. 3, is placed a ring B
formed on its outer periphery with teeth, into
which the teeth of a pinion C, fitted between the
ring B and the outer casing A, gear; the part of
the casing A where this pinion is fitted is enlarged
as shown to receive it. The ring B is formed at
both sides or edges with a projecting rib or
fillet D, which takes into a corresponding circular
groove in the oasing A, so that the ring B is
steadied in its revolution, while the ribs D at the
same time prevent the reduced substance es-
caping from within the ring, except through the
pipe hereafter mentioned. Within the ring B
upon a central shaft E, to which rotary motion
is communicated from a pulley F or otherwise,
are fitted four or other convenient number of
arms G, the outer ends of which are by preference
faced with steel and reach to within a short
distance of the inner periphery of the ring.

The material to be operated upon is fed through an opening H in the side of the outer casing A, and the revolving arms G grind or crush it against the inside of the ring B, to which a slower rotary motion is simultaneously imparted by means of the pinion C, which is mounted on a shaft I. For operating upon substances of large size the inventors employ ribbed rollers or orackers K K, as shown in the plan view, fig. 4, or other breaking apparatus in proximity to the mill before described, so that the substances may be broken up before entering the mill; these rollers or apparatus may also serve to feed the substance regularly to the mill.

The blast created by the revolving arms G in

AR

ORNAMENTAL GRILLING APPARATUS.
RT and science now enter so largely into
most of the ordinary matters of life that
it is not surprising to note that of late their
services have been largely enlisted on behalf of
culinary operations. Their most recent appli-
cations in this direction are embodied in a grilling
apparatus, which are fast multiplying. The latest
of these, which we have just inspected, was de-
signed and manufactured by Messrs. Jeakes and
Co., of 51, Great Russell-street. It is classic in de-
sign, and manufactured to combine the largest
amount of elegance that is possible with the great-
est utility. It is arranged to cook thirty chops or
steaks at once on the "grid," which is provided
with the necessary power of elevation and de-
pression both at back and front, adjustable to the
greatest nicety to suit its position to the heat of the
are. The spare or spent heat of the fire is used to
provide a plentiful supply of boiling water; it also
works a hot closet for plates on the left of the fire,
while on the right an oven is provided, capable
of cooking 1 bushel of potatoes per hour, at the
cost of 14d. per bushel, by a very perfect gas ar-
rangement on an improved principle. The pedi-
ment of the apparatus is constructed to form a
perfect ventilating chamber, for the purpose of
carrying off any vapours generated by the cooking

room in which it is placed. At the back of the and for the general ventilation of the dining fire there is provided a self-acting arrangement, which effectually prevents the boiler flue becoming choked, and also for adjusting the ascending draught of the fire until the proper current has been obtained. The "grid" is manu. factured of polished steel thickly coated with silver, the part not in contact with the fire being solid silver, while the general design of the whole apparatus is carried out in bright steel, ormolu, and metallic electro, in such a way as to harmonise with the highly decorated style of a first-class public dining-room. It has been manufactured for a restaurant in Liverpool, where it will be despatched in a few days. Messrs. Jeakes are the originators of these handsome apparatus for dining-rooms, the "grills" at the Victoria and Ludgate Hill Stations, and the Exchange Buildings Birmingham, being amongst their productions.

While upon this subject we may notice an im proved steam closet for cooking potatoes, which is constructed to cook 3 cwt. of potatoes in an hour. It consists of two compartments, one for wet steam and one as a hot closet for drying off after cooking. There is an outer steam jacket formed over the whole which is heated by the spent steam after leaving the wet compartment, and before being collected into a condenser under the apparatus. The whole process of cooking and heating the closet is carried on with steam at a less pressure than 1lb. per square inch, and the potatoes are perfectly cooked in 15 minutes, and thus the greatest economy is secured. A steamtight joint is effectually made for the doors by a simple contrivance, and the whole is under the most perfect control by regulating valves to the different parts and safety valves for the indication of too great pressure. The apparatus is mounted on an open cast-iron stand, with a provision for carrying off the condensed water that necessarily runs from the doors when opened.

FIG. 4.

FIG. 3.

VAN BRUYSSEL'S ELECTRIC CLOCK.

ELECTRIC CLOCKS.

[ocr errors]

FIG. I.

BL

FIG. 2.

hydraulic test, to be so rigid as to prevent the
valve's rising sufficiently to admit of a free escape
of steam. A compression of a little more than
1-8in. raised the load
upon the valve
from a pressure
of 80lb. on the square
inch to 200lb., in addition to which the two nuts
by which the spring was held down were loose,
and neither guarded nor looked in any way, while
the pillar bolts that carried them had neither
stop collars nor ferrules to prevent their being
oversorewed, so that the valve could at any time
be tampered with, or the engine-man, in re-
placing the valve after taking it out as he would
have to do occasionally for cleaning, &o., might
easily put on 100lb. more than the ordinary
pressure, without knowing it. Indeed, it was a
matter of perfect haphazard whether he loaded
the valve to 1001b, or to 200lb. There was only
a turn of the nut between safety and explosion,
or a single thread between life and death. Such
a valve was indeed no safety-valve at all, but only
a delusion and a snare, totally unfit to be put on
any boiler whatever, but more especially so on a
small portable one, which from the fact of these
boilers not always being in the hands of the most
skilled attendants, should be the more carefully
contrived for simplicity and safety.

The boiler burst at the unguarded manhole, eight rents starting from it, which ripped up the shell into fragments, and tore them away from the furnace tube, which was left uninjured. The manhole cover, which faced towards the stern of the ship before the explosion, was shot through negative current, and as their positions with re the sides of a poop cabin in that direction, spect to the springs of each pair with which they while the main portion of the shell recoiled to. come into contact are alternately reversed, a posi-wards the bow, and embedded itself in a deck. tive and a negative current will be alternately house, the domed crown plate of the shell being transmitted to the distant time indicators. We thrown upwards, and afterwards found on the have recently inspected a number of clocks which deck of a neighbouring vessel, while the bulwarks and from the simplicity of construction and cer- appearance of having been in action. Added to are working upon M. Van Bruyssel's principle, were so splintered that they presented the tainty of action of the whole system, we think this, five men were laid dead on the deck, and it is one which deserves the attention of those two others blown overboard, while another was who have the regulation of public time, whilst so seriously injured that he lingered but a day or it only requires to be better known to come into se before he died. The sight of the dead bodies general use. laid out on deck, and the boiler plates bathed in their blood, is described as perfectly sickening; and reference to these facts is made that the disCONSTRUCTED STEAM astrous consequences may be appreciated of turning out improperly-finished boilers, the im

A NEW system of working clock with great
accuracy by means of an electric current
has been recently introduced from Brussels by
M. E. Van Bruyssel. The pith of the invention
is a novel arrangement of apparatus to be em.
ployed in connection with a a regulating pen-
dalam clock for indicating simultaneously at
numerous and even distant points in any given
town, district, or country the time of the day in
hours and minutes upon clock dials. The ar-
rangements by which this end is effected are
shown in the accompanying engraving. Con.
nected with a regulating clock (the pendulum of
which beats seconds) is the shaft of a com. IMPROPERLY
mutator, shown in front elevation and in plan
view at figs. 1 and 2. The commutator shaft
carries a pinion that gears into a wheel on

the arbor of the minute wheel. This gearing
serves to rotate the shaft once in two minutes.
The commutator shaft carries at its extremity
an ivory cylinder 6, by which the currents
of electricity employed to actuate the clocks
or time indicators will be constantly and al-
ternately changed from positive to negative and
vice versa. The ivory cylinder is fitted with two
insulated metal disos c and d, which are set concen-
trio therewith and dip respectively into one of two
mercury cups e e placed below them and brought
into connection with the opposite poles of a bat-
tery. Platinum wires ff from these discs are
led to one end of the cylinder and laid parallel
to the axis of the cylinder and at opposite sides
of its periphery. Set around this cylinder and
bearing upon its periphery at the part where the
wires are exposed is a series of springs g made
of rolled brass. These springs are affixed to the
back board A of the commutator, and they number
double the number of the groups or sections of
clocks or time indicators intended to be worked
by the regulator clock. These springs g g are
ased in pairs, and each pair is connected by
insulated wires with their respective time indi.
eators. The springs of each pair are so disposed
that they will both be in contact with the wires f f
of the ivory cylinder b at the same time; the one
with the wire of the near disc and the other with
that of the more distant. As, therefore, the cy.
linder rotates the circuit will be opened through
the several pairs of springs g with the several
indicators in regular succession, and the required
impulse will thereby be given through electro-
magnetic apparatus to the hands of the indi.
cators. Fig. 3 shows one of these indicators in
front view, the face being broken away to expose
the hidden mechanism. Fig. 4 is a plan of the
electro-magnets used to actuate the clockwork.
Between the poles of the electro-magnets is a
permanent magnet, carried by a vibrating forked
arm which embraces an ordinary escape wheel,
and at each vibration drives it forward the
distance of one tooth.
This motion is, by
ordinary clock gearing, communicated to the
hour and minute hands of the indicator.
But inasmuch as the platinum wires ff trans-
mit the one the positive and the other the

BOILERS.

consideration of the direction in which the fragments of the boiler were thrown, the manhole portion of the shell recoiling in the other, if cover being shot in one direction, and the main taken in conjunction with the original position of the boiler prior to explosion, as well as with the eight rents which radiated from the unguarded manhole, prove incontestably that it was at that unguarded manhole the boiler first gave way.

N his last report, the portance of which is so sadly overlooked. A Manchester Boiler Assefatngineer of the following interesting particulars relative to the explosion which occurred in one of our large commercial ports at about three o'clock on the afternoon of Tuesday, October 9th, to a small portable boiler employed on board a sailing vessel in driving a winding engine for hauling on board the cargo. This explosion is of a most melancholy character, not simply from the fact of eight persons having been killed, but from their deaths being perfectly gratuitous, since they arose from the improper construction and equipment of the boiler, which might easily have been corrected; while two other men were killed as recently as the 21st of April last by a similar boiler, which was turned out by the same maker, and burst from a precisely similar cause. The boiler, which was not under the inspection of the association, was of about 4-horse power and of vertical construction, baving an internal conical firebox containing two horizontal water tubes running across it. Its size was quite diminutive, which it is important to notice in connection with the very fatal results of the explosion, since the danger of small boilers is apt to be overlooked. Its height was only about 5ft. 6in., while the diameter in the shell was but 2ft. 6in. and in the internal furnace 2ft. at the bottom and 6in. at the top, the thickness of the plates being in. in the shell and 3-8in. in the furnace tube, while the working pressure was about 1001b. on the square inch, the bursting strain, as stated by the makers, being as high as 500lb.

The cause of the explosion was made a matter of the most searching investigation by the coro. ner, who indefatigably pursued the inquiry for three entire days. Neither the makers of the boiler, however, nor the intermediate party who had sold it to the shipowners, were present at the inquest, both excusing themselves on the plea of illness, but the makers were represented by their lawyer, as well as by their manager. In their defence they attempted, as is usual in these cases, to throw all the blame upon the poor engineman who had been killed by the explosion. The legal gentleman tried hard to prove that the engine. man had allowed the furnace tube to be laid bare and overheated, through neglecting his feed, and that water must then have been dashed upon the hot plates, either from the sudden introduction of the feed, or starting of the engine, in conse. quence of which an excessive and uncontrollable pressure of steam had been instantaneously generated, which burst the boiler into fragments with the force of an ignited charge of gunpowder. It may be questioned whether such consequences would have resulted even if the furnace tube had The equipments of this boiler were defective been overheated as supposed, since the feed water both in the case of the manhole and safety-valve. was pumped into the boiler at the bottom, or nearly The manhole, which measured 13in. horizon. so, so that it could only have submerged the furtally by 10in. vertically, was not strengthened nace tube little by little as it rose and cooled it as it should have been with a substantial mouth- down gradually, which could not, it is thought, piece, nor even with a wrought-iron ring, but had have produced any rapid generation of steam. an ordinary internal cover, held up by one or two In support of this a case mentioned in a previous bolts suspended from arched bridges, notwith-report may be referred to, in which water was standing the high working pressure and the pumped into a red-hot boiler without having any lightness of the plates already described. The other effect than so straining the seams from safety-valve arrangement was most objectionable. violent contraction that they leaked like a sieve, Every boiler should have two good valves, whereas this had but one, and that of a most dangerous class. It was fitted with a spiral spring, which proved, on being submitted to a most careful

and the water ran out of the boiler faster thau the engineman could pump it in, which was the first intimation he had of anything being wrong. These remarks, however, must not be misunder.

« EelmineJätka »