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vey away all the generated at
larly supplied with water; 4th
deep under the general level d'a
the boiler that some considere
water level may take place vins
of them empty; 5th, they mas ba
together that no destructive exam
allowed to take place, and tal
cleansed of deposit." Dr. Am
condition very difficult of fi
however, is given here, although
not wish to endorse it in the f
the tubes must be connected wa
of the boiler in such a manner the i
rupture occurring in one of the d
tent of water and steam may
out and discharge itself
ously." It is believed that ing
can easily be attained to a gre
realisation can only be had by ra
of suffering the communication a
be altogether stopped up. As
rules stand no que can for one ans
their soundness, and it will be quent.
that if any generator in the constra
they were fully observed an
thoroughly excellent, ebalinio va
gently, therefore dry steam dat
the engine; the flow of water wi
therefore overheating would be
heat would be absorbed comp
none would be wasted.

the back. In these lie the ends of the head of a
T-shaped bolt about lin. in diameter, which
passes through the back plate of the heart be-
tween the oval holes before referred to, and is
screwed up by a nut. By removing this the
tube can be taken out at any time without disturb-
ing the others. The front plate of the heart,
which is removed when the boiler is cleaned, is
made tight with a lead joint. The furnace is of
brick, and lined with firebrick. The upper part
is covered by firetiles, either made square with
the corners cut off, or otherwise arranged so as
to leave openings through which the products of
combustion escape into an upper chamber, from
which they pass to the chimney. The tiles are
required to compel the gases to diffuse them-
selves equally among the tubes, the area of the
apparatus-the calorimeter, in fact-being so
proportioned that unless the products of coin.
bustion pass through all, they cannot get away
fast enough to the chimney.

This boiler may be divided into three distinct
portions-first, the generating tubes; secondly,
the vessels which serve to lead the steam away
from the tubes, and from which they are sup-
plied with water, which are termed "hearts;"
and, thirdly, the separators and receivers. The
tubes are of sheet copper, and soldered, and
1-12in. thick and 4in. in diameter, by about 6ft.
long. They have at the back end an opening for
cleaning them, closed. by a screw cover; their
front ends are fixed upon the back plate of the
heart. The interior of each tube communicates
with that of the heart by means of two oval open-
ings in the back plate of the latter; the upper
one carries away the steam, through the lower
water finds access to the tubes, which are laid on
a slight incline to facilitate the escape of the
steam. The tubes are laid in eight tiers or rows
one over the other, the distance between the
grate and the lower row being about 18in. or 20in.
The tubes are disposed so as to break joint, a
very essential provision, as will be seen here- In this boiler the tubes are acted on by the
after. The space between the tubes is about 2in. flame in the best manner, and the circulation is
measured horizontally. The hearts are flat-ingeniously provided for. Dr. Alban states that
stayed chambers, with cast-iron sides, tops, and several of these boilers made by him gave perfect
bottoms, and wrought-iron front and back plates. satisfaction, working with pressures of 90lb. to
They are about 42in. high, and something less 150lb. on the square inch. But he partially ad-
in width. The tubes fit into annular grooves in mits that for lower pressures they do not answer
the back plate, which is in. thick, the oval so well, because the volume of steam being much
openings coming as close as possible to the top greater it cannot escape from the tubes with
and bottom of each tube. These openings are lin. sufficient facility. All the arrangements are me-
by 1 in. The interior construction of the heart chanical and ingenious. But the author is of
is peculiar, and of much importance. Division opinion that even better results might have been
plates of strong wrought iron cross it nearly obtained with less expense and more certainty.
from side to side; they are fixed to the back The boiler may be regarded as being absolutely
plate by lugs and screws, and bear against the free from the risk of dangerous explosion. The
front plate. They are curved at the ends, and consequences could in no case be worse than
divide the heart into as many distinct horizontal those of the collapse of a flue in a locomotive,
channels as there are rows of tubes. The use of which, as every engineer is aware, is a matter
these divisions is to guide the steam from the of but too common occurrence. As to the actual
upper oval openings into the vertical channel at merits of these boilers as steam makers, there
the right-hand side, and to keep it out of the is but little available data, as Dr. Alban never
way of the feed opening that the proper water appears to have carried out any accurate ex.
supply may not be interfered with. The width periments to determine the point. The engine,
of the vertical channel must be proportioned to the boiler of which has been described, cut off
the number of tubes in a row; the maker allowed its steam at one-third of the stroke, and worked
lin. for each tube. The steam passes, carrying with a boiler pressure of from 901b. to 105lb. up
some water with it, from the vertical channel to 34 estimated horse power. The fuel used
up the pipe to the separator above.
was a very light, poor, unpressed peat, and of
It remains to be seen how the circulation is this the consumption was 12:4lb. per horse per
effected. A pipe at the right hand of the heart hour. Its calorific value could not have been
extends nearly to the bottom, and opens some more than one-third that of good coal, so that
3in. above it. Through this a stream of water we shall be on the safe side if we estimate the
continually descends from the receiver above, consumption at a little over 4lb. of coal per horse
turns up, and gradually supplies the place of per hour. This is very good work for a non-
that carried away by the steam, as well as find-condensing engine working saturated steam, and
ing its way into the tubes, through the lower the author believes that it corresponds to an
oval openings, to supply that lost by evaporation. evaporation of about 9lb. of water per pound of
The steam, owing to its levity, collects against coal. The defects of the boiler lie principally in
the upper plates of the transverse chambers, its first cost, which must be great, even if iron
and is guided away by the form of the division tubes are used. The circulation, too, does not
plates, without interfering with the water in the appear to be provided for in the best manner;
lower part of the chamber or impeding the but, on the whole, the design is worthy of con-
supply to the tubes. The steam and water pipes siderable attention, and it must not be forgotten
are secured to two horizontal cylindrical vessels that. this is one of the few tubulous boilers which
about 15in. in diameter, and half as long again have achieved any considerable practical success.
as the tubes. They are united at the front end
(To be continued in our next.)
of the heart, and at the back end by two tubes
which carry the steam and water from the sepa-
rator on the left into the receiver on the right.

The author, before entering un
description, considered as s
principles to be observed in desgage
for the generation of steam. Or
permit us to follow the author her
his interesting theoretical elabo
up the theme at the practical p
mences with the subject of circu
-In the ordinary boiler contai
tity of water circulation is left y
care of itself, and, as a restit, m
steam in Cornish and marine ble
is still cold water under their f
sult of this unequal heating is
leaking joints and heavy bih ir
water-tube boilers, however, spa
and the ebullition so general in
special attention must be paid ma
leading away the steam and taking
the heated surfaces. The less te
respect will entail the total
rator, and it may be safely said th
of circulation has given at leas
as any other connected with the
the water tube boiler. The res
circulation which have been prJE
accordance with which tabalos
been designed and made, may be
four classes:-1, boilers with
tion, aided by special devices; **
forced circulation effected by pa
steam, &c.: 3, boilers with
due to gravity unaided by y
lastly, boilers in which the circu
by suffering steam to accumular
locality until it acquires suficien
volume to expel the water from th
is, of course, immediately filed
moment the production of stee
sequence of the absence of waz
first head may be ranked Mami
boilers, as used in the States, t
boilers; under the second, Ab
those of Mr. Howard, of Bedford,
under the third head, boilers the
struction of which is similar
few years since by Mr. Mar
which it is assumed that may
liar; and under the fourth, a burst
a Scotch firm, which, as the
viously utterly wrong, the anar
ticularise.

In describing the examples o
they will be treated in two g
I tabulous boilers, such as Albat
first; and secondly, those in wit
of an ordinary fire-dae are s
placed by water tubes,
Martin's boilers. In each case
as possible, be given of the c
practice, for all the boilers
practice to a greater or less e
indeed, as Galloway and Martin'
tensively employed. Two d
made by Alban were empre
of the dacal cloth

From this last the steam is drawn for the en-
gine. The whole effect of the arrangement is to
perfectly separate the steam from the water, and

the gun when worked on his improved system. It relates, thirdly, to a plan of transporting, training, and traversing an upper or main deck gun, by means of racers or slotways on or in the deck, and of rollers or trucks fitted to the gun slide, so as to readily turn or be turned round on a vertical pivot in the required directions for transporting, training, or traversing the gun. The next improvement consists in fitting a bolt or block to the front or rear of the slide, or to both front and rear, so as to readily drop into a circular slotway or groove, or under a projecting flange, so that when transporting, traversing, or training the gun, the slides may be held securely and likewise be ready for firing the gun much more quickly than on the old plan of catching a pivot point or nipple and using a pivot bar or flap. Further, Captain Scott uses toothed racks upon the sides, decks, slides of vessels for the purpose of transporting or traversing the guns as aforesaid. Another improvement consists in the use of training racks upon turntables when the turntables are used for traversing guns, whether in ships or fortifications of any kind, whether floating or erected upon the land.

or

By this

In our engraving, fig. 1 is a side elevation of a gun slide, with part of Captain Scott's improvements adapted thereto. The slide is shown. ready for pointing the gun, and is held securely against the longitudinal strains arising from firing the gun by means of the head block C, which has a roller with its edge working under the front racer k, and holding down the head of the slide, in which position it is keyed by the wedge g. In order to assist the head or front block C in holding the slide longitudinally the trucks a a', which rest upon the racers, are provided with central flanges which run in the grooves g' g' of the racers and guide the slide in training. These trucks are, in fact, formed somewhat like castors, that is, the flanged roller turns upon horizontal pivots in a block or frame provided with a vertical stud, pivot, or axle which turns in a socket in the gun slide. means the trucks and their accessories are made of great strength to resist and sustain the strain produced by firing the gun. The slide with its gun is trained or pointed by means of suitable power applied to turn the shaft s1s and give motion to the pinion p which moves round upon the rack d; the pinion p is moved fromdtod' by means of the lever e which is secured by the pin f. The short part of the shaft sl which car. ries the pinion p is jointed to the shaft s' by means of a coupling. In order to traverse the slide with the gun so as to work them at another position or port the trucks a and a' are turned to the line of the traversing curves r l by means of a lever applied at b and b'; the pinion p is moved by the lever e from the rack d to the rack d', and is secured by the pin f, and the front block c is uukeyed and turned up ready for transporting the slide by means of the pinion p working round in the rack d'.

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Fig. 2 is a plan view of the curves and racks adapted to the stern of such a vessel as the Achilles," and shows the slide supposed to have been traversed round from the position A to the position B along the grooved racers and

to supply the former, dry and free from priming, T has long been associated with improve moved forward from the traversing rack d1 to

to the engiue. The boiler, taken as a whole,
has two hearts and fifty-six generating tubes,
and two separators and a single receiver for the
two. The details of construction may be briefly
described. The back end plate of each tube is
of wrought iron half an inch thick; a groove is
turned in it, into which the end of the tube is
brazed. In the centre of the plate is a hole 2in.
in diameter, surrounded by a sunken groove to
receive a projection on the cover. This last is
oval, its long diameter being equal to that of the
end plate. It has a projection fitting into the
hole, and another which enters the before-men-
tioned groove. The two oval ears are perforated
for screw bolts, which are tapped, riveted,
and brazed into the end plate. The cover is
fixed on by nuts on these bolts, and is made
tight by a lead ring put into the groove. The
front end of the tube is secured to the back plate
of the heart. It is surrounded by a wrought.
iron ring 14in, wide and in. thick, brazed on,
in order to give strength and a wide face for
attachment. On the inner surface of the tube
are riveted two iron lugs or ears, set about in.
from the end, and made with square notches at

CAPTAIN SCOTT'S IMPROVED METHOD
OF MOUNTING AND WORKING GUNS.
HE name of Captain R. A. E. Scott, R.N.
ments in naval gunnery. The "Scott" gun, and
the "Scott" gun carriage are doubtless familiar
to most of our readers; the efficiency with which
the latter works is notorious. But not contented
with what he has already done, and fully
comprehending the requirements of the service
under the constantly changing conditions of war-
fare, Captain Scott sees where further detail im-
provement may be made, and sets himself to work
to accomplish it. So we have two of the gallant
Captain's most recent inventions to describe and
illustrate in our present article. The first inven-
tion relates, firstly, to a novel method of training
and fighting heavy revolving or pivoting guns
upon the decks of vessels round a fixed centre,
and, when necessary, traversing the guns from
this fixed centre to other fixed or imaginary
pivots at or near the sides of the ship. The
advantage of this plan over the turntable as now
used with or without turrets is that it will
enable the guns to be brought close to the ship's
side and be fired ahead or astern clear of funnels,
masts, boats, and other ship's gear. The inven.
tion consists, secondly, in the use of a mantelet
or bullet-proof protection to cover the crew of

r'. The front block C has been let down and keyed, and the fore trucks a a' have been turned ready for pointing the gun, and the pinion p the training rack d, the lever e being secured by the pin ƒ as before. The rear trucks a' a' are still in the traversing position, the gun being supposed to be running out, but its weight not yet far enough forward to allow them to be turned; when this can be done the rear trucks a' a' are to be turned to a line with the training racer l' and the slide with its gun will be then ready for working in the direction B.

Fig. 3 shows a gun mounted with four fixed trucks n n', two at each end of the slide, and having four movable trucks m m1 capable of being brought in and out of action by the capstan nuts e e'. in every position the slide is held securely down to the deck by the strong blocks or rollers ccl, the lower edges of which work under the edges of the racers 1 lk k l'l and k'k', which are grooved for that purpose. These blocks or rollers cc' serve the further purpose of resisting the longitudinal strain of firing when the gun is fought with its slide fixed to the central pivot. A strong bullet-proof protection or mantelet d (fig. 3) is suitably supported at the front of the gun, the muzzle of which projects through an aperture in it. This mantelet revolves with the

CAPTAIN SCOTT'S IMPROVED METHOD OF MOUNTING AND WORKING GUNS.

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slide and thus affords shelter to the gun's crew. The position of the slide and curved mantelet shown in elevation at fig. 3 is indicated by the dotted lines in the plan view fig. 4. The gun is supposed to have been fired upon the pivot h in the direction C (fig. 4,) and to be required to be traversed to another position in order to fire in the direction D.

By referring to fig. 3 it will be seen that the rear flap g has been passed over the pivot a and keyed, and the front flap ƒ has been released from the pivot point p (fig. 4), and is in process of being turned up. The movable trucks m m must be brought into action so as to just take the weight of the slide and gun off the fixed trucks n n'. This is done by turning the capstan nuts e e' by the aid of suitable levers. When this has been effected, the slide and its gun can be traversed round to another position as at D upon the curves or racers ll', and on its fore part reaching the pivot point h1 the front flap f is to be secured to it. The trucks m m are moved out of action, and the rear flap g released and turned up. The slide and gun are now ready for pointing in the line D and can be trained round to the direction indicated by the

dotted lines.

Captain Scott's second invention is represented in figs. 5, 6, 7, and S. It consists in placing balks of wood or iron plates along the sides of platforms or slides instead of along the centre, as at present, thereby leaving the central part clear for the other appliances required to work the gun. Another improvement relates to the adaptation of a self-acting compressor or apparatus, which is brought into action by the recoil of the gun. The invention further consists in adapting

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the endless chain or other running in and out gear to the centre of the slide to which alone it is to be suspended or fixed; by this means only a single endless chain and set of gear will be required. The invention further relates to a plan of reducing the jar or shock to which metal gun carriages are exposed at every explosion of the charge. In the engraving fig. 5 is a sectional elevation of part of a gun carriage and slide with the improved compressor, with other of Captain Scott's improvements adapted thereto; fig. 6 is a sectional plan view of one of the side balks; fig. 7 is a transverse vertical section of the gun carriage and slide i and fig. 8 is a side elevation of the same.

necting it with the lever q, which works the chain clutch ƒ (figs. 5 and 7); another rod o completes the connection of the compressor, chain clutch, and rear eccentric roller p'.

To the side of the slide, either inside or outside, or both, balks of wood or metal d or a combination of the two are attached, having a free lateral motion, but firmly held longitudinally; the sides of the slide are filled in with wood, and a sufficient taper is given to the whole or any one of the parts to ensure perfect freedom in the motion of the carriage compressor plates b b when the gun is run out, and yet ensure sufficient compression on recoil. The running in and out chain r is placed in the centre of the slide, and may be worked at the rear as at present. On the under side of the bottom plate the fixed part g' of the clutch is attached, and cimmediately under it is the movable part f; the extremities of the movable piece ƒ are connected by means of the rods kk, (fig. 7) with the crank and shaft and h, which, as before stated, is connected with the lever q (fig. 5). The rear eccentric roller p' is worked by the ordinary ec. centric and socket p2, which socket is connected by the rod o with the chain clutch and compressor lever q. An auxiliary means of working the whole is provided at the outer extremity of the shaft h, to which is attached a socket 7 (figs. 7 and 8), and a loose cam m acting with a stop joint in connection with the socket, so as to throw it out of action by striking the fixed stop? when the carriage is run out.

The compressor is composed of two plates b b which are hinged to the lower extremities of the levers a a, and hang down on each side of the long side balks A. There is an inside plate which is slotted, so as to hang freely from and be supported by the bottom plate of the carriage, as shown in fig. 5. The levers a a turn on the centre bolts y y, which also connect them securely to the brackets; motion is imparted to the levers a by a right and left handed screw t (fig. 7), which passes through holes in the brackets; on the outside end of the screw t a circular nut p and plate r cast in one piece are placed. The former is slotted so as to rest between two projections of the lever head, and the latter is perforated with holes round its outer part, as shown in fig. 8, so as to enable it to be keyed in any position to the lever a as shown; this constitutes the adjusting part of the arrangement. The inside end of the screw t is attached to one extremity of the lever x (fig. 5), the other end of which is secured to the rod e, thus con

The action of the compressor is as follows:The carriage having been run out and off its rol lers, the compressor plates hang freely between and on both sides of the balks, as shown in

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necting it with the lever, wh chain clutch ƒ (figs. 5 and 7); another pletes the connection of the compres clutch, and rear eccentric roller p

MAY 10, 1867

THE MECHANICS' MAGAZINE.

fig. 6. The moment the gun recoils the com.
pressors run up the inclines 1 1, and become
jambed, and thus retard the recoil of the gun.
In order to run the gun out again the ends of the
levers are placed in the sockets p2 and 1, or in
either of them, for the purpose of forcing them
down, by which means the rear eccentric rollers
are brought into action and the chain will be
clutched by the parts ƒ and g'. The compres
Bor b b will be released through the action of
the rear roller eccentrics before the carriage is
raised. The combination of the levers acting
on the rear roller eccentrics as well as the
clutch crank shaft and the compressor screw
will make these operations simultaneous. The
compressor screw t acts on the compressor
levers a a through the nuts in their upper cx-
tremities, the outer nuts p being, as before
stated, circular, but the inner nuts u are square
to prevent them from turning. When the gun
has been run out the levers or bars which have
been shifted in the sockets are thrown upwards;
by this means the rollers go out of action, the
chain is released, aud the compressor screw t
is turned so as to bring the plates bb nearer
together and ready for the discharge of the gun.
Should the compression be insufficient the key s
should be removed, and the disc r turned a point
or two in the direction required, and the key re-
placed; if the compression is too great the
same operation may be performed in the oppo-
site direction.

Captain Scott's last improvement relates to
the use of wood or other suitable material as a
buffer to absorb the first violence of the recoil, to
which end the bracket carrying the gun should
be so formed as to admit of a cushion or bearing v

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(fig. 8,) being placed so as to rest between the APPARATUS FOR OBTAINING LATITUDE | is for adjusting the artificial horizon to the true
side plates and on the main framework so as to
receive the trunnions of the gun, which should
rest in this cushion, either with or without plates
of metal intervening.

AT

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horizon; the cover r is to prevent this screw AND LONGITUDE. from being disturbed by accident; the telescope HE accompanying engraving represents as thus constructed is attached to an ordinary some highly interesting improvements in sextant. In this way the artificial horizon is apparatus for obtaining latitude and longitude, made to follow the real horizon, and thus when and which bas recently been patented by Mr. C. the sun is visible but the true horizon is ob. F. Varley, a gentleman whose name is insepara- soured, its altitude can by this instrument be bly connected with the laying of the Atlantic measured with sufficient accuracy for ordinary telegraph cable. Fig. 1 is a longitudinal section, navigation. The torsion of the fibre which supand fig. 2 a transverse section of the instrument ports the pendulum is not great; it is kept coninvented by Mr. Varley, the other figures show-stant by the spring s, and is compensated for by ing some of the parts separately. Between the trial. The projection w from the piece m, and object glass A and the (positive) eye piece B of which enters the cup v, is to limit the motion of the telescope a chamber is inserted whose two the pendulum so as to prevent l and h from being ends g are made of glass, and whose interior is injured by rough usage. The tube x is for filling filled with pure water. A U-shaped springs the apparatus with water. Mr. Varley makes (figs. 1 and 2) stretches a silk fibre f and keeps it the spring and pendulum of the platinum silver tight; this fibre passes through a light metal alloy supplied by Johnson and Matthey, as it frame C, and also through a piece of metal m, does not oxidise. To obtain pure water free from about in. long and in. in diameter, to which air for use in this instrument he puts some also it is cemented. This piece of metal m forms lumps of clear pure ice into a bottle. This appathe pendulum and carries two heavy-headed ad- ratus can be used for ascertaining the elevation justing screws a and al for adjusting the position above the horizon of lights and other objects, of the centre of gravity. A third screw b con- and thus furnish the data for computing their nects the light lever 1, which carries at its end distance from the observer. the horizon line h (figs. 1 and 3), which also is a silk fibre. The screw a is for adjusting the height of the horizon line h; the screw al is for LONDON ASSOCIATION OF FOREMEN rendering the horizon line horizontal. The pendulum is able to swing either longitudinally let- or of the this results from the way in which it is hung by means of the square frame C already referred to and shown in plan on an enlarged scale in fig. 4. The silk fibre f passes from the spring s, down through the hole c, up through the hole d, down through the hole d', and up through the hole ct to the other extremity of the spring s.

PHOTOGRAPHY IN 1787.
Ta recent meeting of the photographical
section of the Literary and Philosophical
Society, Mr. J. Baxendell, F.R.A.S., vice-presi-
dent of the section, in the chair, Mr. Brothers
read the following note on photography in 1787:
-It is generally supposed that the earlier
attempts to use nitrate of silver for producing
pictures of lace, leaves, and other objects on
white leather or paper were made by Wedgwood
and Davy about the year 1802; but it will
appear from the following extract that at least
fifteen years earlier than the date named, and
within ten years of the time when Scheele in-
vestigated the subject of the action of light on
the salts of silver, the possibility of utilising the
action of light was known. The title of the book
from which the extract is taken is "Rational
Recreations in Natural Philosophy," &c., by W.
Hooper, M.D., 1787, and the paragraph is
headed "How to print letters by sunlight."
"Dissolve chalk in aqua fortis to the consistence
of milk, and add to that a strong dissolution
of silver. Keep this liquor in a glass decanter,
well stopped, then out out frond paste the paper
on the decanter, which you are to place in the
sun in such a manner that its rays may pass
through the places cut out of the paper and fall
on the surface of the liquor. The part of the
glass through which the rays pass will turn
black, while that under the paper will remain
white. You must observe not to move the bot-
tle during the time of the operation."

At the same meeting Mr. Coote exhibited
some snow scenes, the negatives of which were
taken on collodio-albumen plates. Some of
these beautiful views were slightly defective in
the high lights, a number of vein-like markings
appearing in the sky and foreground.

To the side of the slide, efter side, or both, balks of wood cr combination of the two are started free lateral motion, but firmly bel nally; the sides of the slide are wood, and a sufficient taper is give or any one of the parts to e freedom in the motion of the carriag plates b b when the gun is run o sure sufficient compression on real ning in and out chainz is placed of the slide, and may be worked at present. On the under side of the b the fixed part g' of the clutch is immediately under it is the more extremities of the movable piece by means of the rods kk, (ig. and shaft i and h, which, connected with the lever ( centric roller p' is worked by t centric and socket p, which soc by the rod o with the chain cla pressor lever q. An auxiliary ma the whole is provided at the outer the shaft h, to which is atac (figs. 7 and 8), and a loose an stop joint in connection with the throw it out of action by striking when the carriage is run out The action of the compress plates hang A The carriage having been ran o

pressor

Mr. Wardley stated that these defects were entirely caused in the development, and had no Connection with the character of the collodion used or with the preparation of the plate. He considered that the imperfections were produced entirely by the repellent or nonmiscible nature of the solutions, containing acids and salts, used in development, acetic acid being one of the chief causes of the defects. Another source of the evil may be a low temperature and the developing solution being allowed to rest, even for a moment, on the plate. Such defects may be produced in abundance on any kind of dry plate if the developing solution is allowed to

rest.

The water effects two objects, the one that of deadening the motion of the pendulum so that the rolling of the ship does not set it sensibly swinging, the other that by its refracting power it brings the centre of motion of the image within the telescope to coincide with the centre of motion or support of the pendulum carrying the horizon h. An adjustment may be provided to make this coincidence as accurate as may be required; it is effected by the two prisms p and p. One or both can be moved so as to increase or diminish the thickness of glass through which the light has to pass, and by this means an effect equivalent to the elongation or shortening of the water chamber is obtained; or a double object glass may be used, and then by adjusting the distance between them, and between them and the front glass g, the motion of the image and of h are made to coincide. The U-shaped spring carrying the pendulum is mounted on a spring i, which is raised or lowered by means of the milled head o, whose screw of passes through a packing g to make it watertight; this corew

ENGINEERS.

monthly meeting of members of

this society took place on Saturday, the 4th inst., at the London Coffee-house, Ludgate-hill. Mr. Joseph Newton, president, occupied the chair, and the spacious and well-appointed assembly room henceforth to be devoted to the business of the association was quite full. When the routine duties of the sitting had been disposed of the chairman proceeded to deliver a lengthy and interesting address. He reviewed the past history of the institution and congratulated his fellow members on its steadily increasing influence and value. It was satisfactory to be able to announce that they now had a local habitation in all ways eligible for the purposes of the society He considered it fortunate that they were fairly established in the heart of the city, and where they had abundance of room for the reception of their friends. As in the past the society had been completely successful, so in the future it would be yet more prosperous. All that was necessary to ensure this was earnest and cordial cooperation on the part of the members. not for them to rest and be thankful, but to rest and then move on with increased vigour. The chairman appealed to the honorary members to attend and take part in the proceedings of the association. Among those members there were gentlemen eminent in every department of science, employers of labour, military and naval officers and others, constituting indeed a mine, so to

It was

Irvine

readily allow the planes to furl or fold up like a
screen or map, if this be found desirable.
Mr. Hurry. I intended to mention this in my
paper.

When the plane of the kite was made flatter, it would ascend, and the string would be made more perpendicular. Then, again, with the wind at the back of the kite, there could be no doubt that it could be held in position, the same as in the reverse case; that the screw on the under side of the machine, as described, would act as the string of the kite in the way described, had this objection, that it would be using its power against itself, which would be something like a man seating himself in a wheelbarrow, and trying to wheel himself forward.

Mr. Bright, having reiterated his statements, considered it desirable to construct a model large enough to carry a man, and in reply to a difficulty suggested by the chairman as to the expense, said, he thought as he had given his experience to the world, the public should take the matter up.

speak, of intellectual and professional wealth. That mine he wished to open up for the advantage of the institution. Numerous other points were touched upon with considerable emphasis, and all had a bearing on the prospective usefulness Mr. Denham referring to the diagram, where a of the society. Finally Mr. Newton declared the small weight, acting horizontally, is shown holding new meeting place open for the despatch of a larger weight in equilibrium upon an inclined business. The first question discussed was one plane, it is evident that if the plane yields to the having reference to a scheme of life assurance, slightest extent, as in air, the balance will be deand Mr. Fothergill, of the Royal Insurance Com-stroyed, and a rapid horizontal speed will result. pany, having lucidly explained the terms upon Whatever the dynamic value of this may be, it which each member's life might be assured for is very gratifying to find that the theory of flight £100, a committee was appointed to examine into is now being brought within the verge of tangible and report upon the whole subject. Mr. James formulæ. An angle of rise of 1 in 3,000 for a next read an elaborate and emi- speed of 60 miles per hour is estimated, nently practical paper on "Indicating the according to Mr. Hurry's formula. My own exPower of the Steam Engine." This was illus. periments have shown me that at this speed the trated by diagrams and excited great interest. angle of a plane and duly proportioned weights, Messrs. W. Naylor, Keyte, Fishwick, Aland, the as in the wing and body of a bird, is scarcely chairman, and others took part in the discussion measurable, and having been near and surprised Mr. Wenham. Our friend Mr. Green, the which followed, and which owing to the lateness numbers of large tropical birds in all positions of aeronaut, has just handed me this model to illus of the hour was eventually adjourned. We flight, when this at all approaches the maximum trate the effect of two superposed screws. It is cannot but congratulate the association upon its speed, the angle of the wing cannot be detected a very well made piece of clockwork, which runs migration from the comparatively obscure loca- by the eye alone. Recent discoveries in electri- for several minutes by a wound-up spring, and lity of Doctor's Commons, and the admirable ac- city justify the inference that an electro-magnetic was adapted to raise and lower and propel a commodation of its new quarters. machine may be constructed lighter for its small balloon some years ago at the Polytechnic power than any other motor; the oly objection Institution. Now, you will observe that, with is the expense of working it; but if the cost is one screw only, it produces a strong current of fifty times as much as steam in this case it air; but, as Mr. Green has just shown me, by SOCIETY OF GREAT would be worth while to apply it. There is yet superposing another screw the current is deanother observation that will admit of a reply. I stroyed and not perceptible, thus furnishing an ing-machine becoming affected by a current of allude to the risk of being blown over, or a fly-experimental illustration of my first assertion. wachow I believe this to be impossible. The machine will be no more affected by currents of wind impinging against it than a balloon, as it travels in the moving mass of air, whichever ing on the machine will be that caused by its own way it may turn or blow, and the only wind aot motion through the atmosphere. After a strong wind the machine might be stationary with respect to the earth, but with the wind the land speed would be doubled; but in either case the Mr. Artingstall's paper we have another instance progress through the air itself is the same. In of a theory totally different from any that has preceded it. In the present state of the science, controversy in such a case is undesirable until justified by further practical facts. We had best record them all.

AERONAUTICAL

BRITAIN.

the two preceding numbers of the MECHANICS' IN MAGAZINE we have given abstracts of the papers read at the last meeting of the above society. We now append the interesting discussion which followed:-Mr. Wenham: I will first make a few remarks concerning the screw. This is, perhaps, in all respects perfect as a propeller for aerial machines; but its effectiveness for this purpose depends upon the condition that the screw must work through the air at a speed nearly equalling that due to its pitch or the angles at which the blades are set. For the mere purpose of raising a weight, as in the model before us, I consider that it is utterly valueless, and that the misdirected attempts that have been made to apply it in this way have been one of the greatest drawbacks to aerial navigation. Of all things this is the most easily tried, and the least satisfactory in its result. Many instances have come to my knowledge where the experiment has been made by different parties quite independently of each other, but all have

failed. In one case the screw was nearly 20ft. in diameter, and the utmost power of five men applied to it would not cause it to raise a weight

of half a hundred. The screw is held back from

its work, and does nothing else but draw down a current of air instead of making progress upon a fixed column, and my own experiments, made with a vertical screw or fans of various forms 6ft. in diameter, driven by gear and accurately made, having been equally satisfactory, I could never raise or sustain a weight exceeding 101b. Then as regards the double or superposed screws of Mr. Bright, with motion in opposite directions, the under screw, to be effected at all, must have its pitch greatly increased to perhaps four or five times that of the upper screw in order to obtain any effect whatever upon the current of air coming therefrom, and even then it must act with great loss. The first steamboat that was made by Bell, at Glasgow, had two paddlewheels on each side, one close behind the other, and the speed being the same, the second had to run in the current produced from the first, and being found useless, the plan was never repeated. Also, in one of the first screw experiments recorded, one screw was made to rotate in an

Mr. Oliver Byrne thought that force was not
developed in the way supposed by the writers of
some of the papers.
the velocity or weight of the body put in motion,
It was not due so much to
as to the suddenness or short space of time
within which it was arrested. Thus the hammer
of a man who launched a ship was made to raise
itself was heavy, or the velocity with which it
a very great weight-not because the hammer
was wielded was extraordinary, but because it
was stopped within a very short space of time.
He had observed the flight of the largest birds,
and had noticed that the ease with which they
kept their place in mid-air was due to the sud-
denness and rapidity of the movements of their
wings.

his paper as to the fact of models having been
Mr. Bright reiterated the statements made in
constructed which not only ascended by the
mechanical powers they contained, but had also
carried attached weights.*

Mr. Hurry thought there could be no question
as to a fan of this description raising a weight
tion was, how far, it could be practically applied
-the toy kite demonstrated that; but the ques-

as they were called, in rotary steam engines, and
Mr. Oliver Byrne referred to the dead points,
to the impracticability of constructing large
magnetic engines; but his arguments were after.
wards shown by Mr. Hurry to be fallacious, as
many places where the economic use of steam is
rotary engines were already in general use in
not of much consequence, and although it would
be found impracticable to construct electric
engines of a large size, on account of the dis-
tance at which they would require to be placed
to obtain a high degree of magnetic power from
from each other, it was by no means impossible
batteries.
a small space by using a large number of small

knowledge of the power of the suggested aerial
Mr. Stephen Ballard pointed out that some
the windmills now in use, as they performed a
screw might be obtained by a careful study of
certain quantity of work under a given amount
Experiments and deductions might be made for
of sail, with wind travelling at a certain velocity.
data so to be collected for the purpose of ascer
taining what would be the power of the screw
upon the air.

thanks to the chairman and others who had conThe proceedings were then closed by a vote of tributed papers.

meeting, when the discussions upon the foregoing It is intended shortly to call another general theories will be resumed previously to reading

new papers.

Legal Intelligence.

VICE-CHANCELLORS' COURT
April 26.

(Before VICE-CHANCELLOR WOOD.)

FARINA V. CATHERY AND ANOTHER.

Johann Maria Farina, of Joseph's-platz, Cologne, the well-known manufacturer of Eau de Cologne, instituted this suit to restrain the Farina, of Joseph's-platz, Cologne, from unfairly defendants, who are agents of Johann Maria imitating the plaintiff's label.

The Vice-Chancellor thought the label com plained of was too close an imitation of the plaintiff's, and he granted an injunction.

Sir R. Palmer, Mr. Druce, and Mr. Law appeared for the plaintiff; and Mr. Willcock, Mr. Downing Bruce, and Mr. Brooksbank for the defendants.

how far a practicable area of fan or screw would lift a practicable weight by means of a practical force? He thought that the round screw would not hold, and they had it from Mr. opposite direction to the other, through a hollow the weight was held by the screw, the slip would Wenham, that for starting or supporting, where axis, just as in this model, but, for the same reasons, the boat was found to go faster when be perpendicular; this would be the case in the outer screw was removed. It is true that water, but in air, which was so much more model machines have been made on this prin. buoyant, he thought the effect would be much ciple impelled by a wound-up spring, that will rise greater; he therefore thought that the use of and carry a weight, but at what expense of power? the screw acting as a direct support would not I think that from four to six horse power for be found practically advantageous. He did not every hundredweight raised will be the lowest dispute but that a screw might be made to take estimate. Our member, Mr. Butler, will shortly up a small weight, as in the case of the model have one of these same machines, about which which had been mentioned, but he thought that so much has been said, and has kindly offered to found as good as an inclined plane. The action for practical purposes it would certainly not be lend it, for the purpose of having the amount of power given off by the spring accurately tested. in the case of the kite, as mentioned in Mr. St. As to Mr. Hurry's paper, in my opinion making ing two forces, the wind in one direction and Martin's paper, was clear and distinct, there bethe supporting planes undulating may have some advantage, as this plan will give rigidity in the the string in another, and when those forces £9,500, but were in equilibrium, the kite remained still. line of motion, and prevent the surfaces from bagging, which I have fonnd some difficulty in preventing in my own experiments, and will also

*We purpose shortly to publish Mr. Bright's paper in extenso.-[ED. M. M.]

EDMUNDS v. BROUGHAM.

this case, which was before Vice-Chancellor We understand that the terms agreed on in received £5,000 in lieu of all demands. The Stuart, are the following:-The plaintiff has claim originally made by the plaintiff was for defendant (Mr William Brougham), claimed as a set-off, a sum at the rate of £150 per annum for thirty years from the plaintiff for board and lodging at the house

the

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21

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Mr. Oliver Byrne referred to the is as they were called, in rotary an of to the impracticability of cust it magnetic engines; but his argunear rwards shown by Mr. Harry to b trotary engines were already in

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MAY 10, 1867.

THE MECHANICS MAGAZINE.

of Lord Brougham while he was acting some. what in the position of a private secretary.

May 2.

(Before VICE-CHANCELLOR SIR R. MALINS).

GREENWOOD v. TONGUE.

This was a demurrer to a bill filed for the specific performance of certain agreements with reference to patents for machinery for combing China grass. The grounds of the demurrer were vagueness, one sidedness, and the involving of obligations which could not be enforced.

Mr. Glasse and Mr. Bagshawe appeared in support of the demurrer; Mr. Baily and Mr. J. N. Higgins for the plaintiff.

The Vice-Chancellor overruled the demurrer simply. Costs reserved.

The motion for an injunction to restrain the assigning or changing the letters patent granting licences, &c., was then brought on, but stood over on an undertaking in terms as settled.

COURT OF COMMON PLEAS.
April 26.

(Sittings in Banco, before LORD CHIEF JUSTICE BOVILL, and JUSTICES BYLES, KEATING, and SMITH.)

THOMAS V. HYAMS.

This was an action to recover damages for the infringement of the plaintiff's patent for a sewing machine; and at the trial before Mr. Justice Byles the verdict was for the plaintiff, but there were certain points of law raised, and these, it was said, would be discussed in the Court of Error.

Mr. Edward James, Q.C., now moved for a new trial, and argued at considerable length that there was misdirection by the learned Judge, because he had not properly left to the jury the questions of the novelty of the invention and its usefulness. He further submitted that the verdict was against the weight of evidence.

The Court held that there had been no misdirection, and that the verdict was warranted by the evidence. Rule refused.

Correspondence.

PRESERVATION OF LIFE DURING NAVAL ENGAGEMENTS.

rescue ships, that is, vessels whose build, fittings, and stores, and the training of whose officers and crews should be carefully and exclusively adapted to the special purpose of saving life from drowning (and we might add sheltering the wounded); and as nothing could interfere with the build and accommodation of those ships being made such as to ensure the very best sanitary conditions, they might generally be employed as health ships or hospitals for the fleets on active service. In shape, rig, colour, &c., such rescue ships should be conspicuously different from all other ships, while besides, by means of peculiar flags, lanterns, &c., it should be arranged that such ships could be easily recognised by friend and foe at night as well as in daytime. I need hardly say that the said (international ?) rescue ships should under all circumstances be neutral and respected by all, their officers and crews being strictly bound to observe that neutrality; while by international agreement and treaties the combatants of all nations should be prohibited by the severest and most ignominious penalties from using, for the purpose of stratagems, any signal or mark peculiar to the rescue ships.-I am, Sir, yours, &c., G. J. GUNTHER. Erzgebirge, Saxony, April 29.

FOULING AND CORROSION. SIR,-I have been a good deal interested in the question of the fouling and corrosion of iron ships and have read everything which has appeared respecting it with avidity not only in your valuable paper but in every other that has come before me; consequently I have read not only that article referred to by Mr. Maitland in your last impression but also the abridged specification of M. Bernabé's invertion, and must confess that I was much of the same opinion as that expressed in the article, namely, that the process described in the specification was virtually that which had been used for many years. Now, I have had much experience in electro-metallurgy for many years past, and have tried to render the surface of different metals clean more perfectly and more expeditiously by making them first positive before making them negative to deposit a coating of another metal upon them; but I have never obtained a sound deposit by so doing except the metal on which I wished to deposit was pure, such, for example, as thickening a coating of silver. In that case I always do it, and I think it is the best method that can be employed; but for depositing a coating on an impure metal I do not believe in its efficacy. I have tried to deposit copper on iron in that way more than two years ago; but found that I could obtain a much better result by first pickling the iron in chlorhydric acid and then brushing it in an alkaline solution with a fine wire brush till perfectly bright before putting it into the ordinary cyanide depositing bath. By that means an adhering film can be obtained that will stand a red heat without blistering, even on cast iron; but if that film were increased to the one-hundredth of an inch it would stand no such test.

I have tried very many thicknesses of deposit from the thickness of an onion skin to 3-16in., and it is only the thinnest coatings that will stand a red heat without blistering, and that only when the cleansing has been performed with the most scrupulous care. No doubt this is because of the imperfect adhesion of the deposit through the impurities in the iron and the difference of expansibility under heat of copper and iron. Further, I have tried to deposit pure copper on commercial copper by first making the copper positive so as to thoroughly cleanse it as I had done iron; but the deposit would not adhere, and the reason was very clear to me. All commercial copper has lead and other impurities in it, and when the copper is made positive these are left as a kind of mud on the plate, while the surface of the copper is dissolved away, and the like happens to all impure metals when they are made positive by electricity in any electrolytic solution, unless it be an alloy of different metals in their electric equivalents.

TO THE EDITOR OF THE MECHANICS' MAGAZINE." SIR,-Permit me, in continuation as it were of some remarks on the "Introduction of Arms of Defence into Modern Armies," published in the MECHANICS' MAGAZINE of May and October, 1857, and August, 1866, to add a few suggestions relative to the prevention of loss of life in naval warfare. The great protection against the enemy's projectiles which shields of a construction peculiarly adapted to the circumstances of that warfare would afford to the men engaged in boarding, passing under the enemy's fire, landing on a hostile coast, &c., may be inferred to a great extent from my previous remarks. Doubtless, one of the most important duties of the authorities is the protection by proper precautionary measures of the sailors and soldiers against the danger of drowning. The least that could be done and easily done too-but which I am afraid generally is not done, is the supplying each man with a portable lifebelt as part of his usual personal outfit, and with instructions how to use the same in cases of emergency. Of course, on board of ships of war, the arrangements and apparatus for the destruction by far outweigh, perhaps unavoidably, the means for the saving of life; but to mention only one out of many openings for But suppose now all these difficulties overcome improvement, it would certainly not at all interfere and I believe that copper can be made to adhere with the service if each man-of-war was supplied firmly enough to iron for all practical purposes, if with an extra number of lifebuoys to a far greater that were the only difficulty. Suppose the plates extent than hitherto, the which lifebuoys, during of the ship's skin coated in detail, they have then an engagement, should be continually dropped to be riveted together, and then how are the rivet overboard, so that a large extent of the surface of heads to be protected? Certainly there are two the water would be strewn over with a number fapparent ways out of that difficulty. The one is to them, thus offering numerous chances of rescue o coat the head of the rivet first, and the other is to the drowning crews of sinking ships. The object use screw bolts coated with copper. With the of spreading the life-saving agency of the various coated rivets I have found that the copper spreads apparatus over a larger area would be greatly as- and peels from the head of the rivet in the process sisted by adding to the usual lifeboats, lifebuoys; of riveting. The screw bolts I have not tried also life-nettings and life-guide lines, that is, float- because of their cost, and the imperfect joint that ing lines which are connected with and extend from would be made. Certainly there is one other way one or more buoys, &c., and which are to serve as which seems perfectly easy in theory, but from exguides to the drowning men who may happen to be perience I know is not so easy in practice-that is, at a distance from the buoys. It strikes me, how coating the heads of the rivets after riveting. A ever, that the sublime object of saving the life of cell with one side out can easily be made to adhere fellow-men-in the accomplishment of which men to the side of the ship by pneumatic means or of all nations should show a noble rivalry-could otherwise, and the deposit can be made; but then be far more effectually gained if every squadron or the previous cleansing is the difficulty, and the fleet were accompanied by one or more life-ships or adhesion depends upon that. Besides, when any

295

solvent solution is put into the cell for cleansing an action is set up between the copper and the rivets, and they coat themselves with a loose film of cop per which prevents all subsequent adhesion. Even under a positive current the rivet heads will coat themselves when in the presence of copper, in a cleansing solution. The Viscount de Chabannes says in his report that "it is not even necessary that the copper should be exempt from all impurities as that the deposit upon iron by means of electricity is perfectly pure!" No electro-metallurgist could suppose that it was necessary; but then the Viscount is not an electro-metallurgist. No doubt this problem is a very difficult one, and if M. Bernabé had brought anything new to assist us in its solution, all honour to him; but I for one cannot see that he has either in mode of treatment or result obtained. But time will prove.-I am, Sir, yours, &c.,

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EFFECT OF WATER ON STEAM BOILERS, SIR,-After the discussion on my paper, read before the Society of Engineers, on March 18, on "Water and its Effects on Steam Boilers," I wrote an addition to the paper and gave it to be published with the paper, but I find it has not appeared, and the manuscript has been lost. shall feel greatly obliged by your kindly inserting this letter in your next publication. Nearly all, if not all, waters used in steam boilers may be divided into three classes. 1st, those which form incrustation in boilers, but do not contain enough permanently soluble salts (as common salt, &c.) to render them strong saline solutions in the boiler until after some considerable time. The Thames water above Kew and some well waters are of this class. 2nd, those waters which form little or no incrustation, but from the fact of their containing a considerable quantity of permanently soluble salts rapidly become strong solutions in the boiler, and set up galvanic action between the brass and iron wherever they come in contact. The waters of the deep wells of the London Basin, but more especially sea water, and some waters into which sea water percolates, and the Thames at Crossness are of this kind. 3rd, those waters which both form an incrustation and also rapidly become strong saline solutions in the boiler and corrode the metals. The water from some of the London pumps (Bishopsgate-street, &c., analysis of which were given in my paper), are of this kind. It follows from the above, that the injurious effects of the various waters on boilers is either; the formation of an incrustation the formation of a strong saline solution, which corrodes the metals and causes leaks, &c.; or both of these together to a greater or less extent. Before any efficient remedy can however be applied to prevent these evils (or which perhaps incrustation is the least) the composition of the water must be known, and this can only be found by an analysis of the water. composition of the water being known, the remedy, if any, is easily found. For waters of the first class as the Thames water above Kew, &c., where the evil to be prevented is incrustation, a little carbonate of soda, or still better caustic soda, added in solu tion to the water in proper quantities will entirely prevent incrustation, and will not set up other mischief. This will be found to be much better than any other substance, patent or otherwise, but it must be done properly and in proper quantities. It will, in the long run, be less trouble then removing incrustation, and the boilers will last longer, besides the saving of fuel. The only remedy for the formation of strong saline solutions is to blow off the boiler partially or completely_whenever the water is beginning to do mischief. To adl soda to these waters would be to increase the mischief and do no good. The effect of a little fat being put into the boiler where very salt water (as sea water) is used is this:-Common salt is as soluble in cold as in hot water, and separates the surface as a scum or scales as the water evaporates, and causes priming. The fat, when put into the boiler, melts, and being lighter than water, floats on the surface in a thin layer, and covers the salt preventing priming, but it does not prevent the action of the water upon the metals; and the addition of fat to a boiler is in itself highly dangerous.-I am, Sir, yours, &c.,

HENRY K. BAMBER, F.C.S., 5, Westminster Chambers, Victoria-st., S.W., May 7.

The

Mr. Gutzknow presented to the California Academy of National Sciences a sheet of chemically pure silver, 3ft. in diameter, about 3oz. in weight, and as thin as fine paper. The colour was beautifully white, and the texture like fine lace. This silver was obtained by mixing solutions of protosulphate of iron and sulphate of silver in a large dish, when the silver rose to the surface and there formed into a sheet. Successive sheets will rise with each stripping. This easy mode of obtaining chemically pure silver is of much practical value.

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