[44856.]-Coins.-ERRATA.-Line 12, for "a
shield crowned," read, four shields crowned; line
40, for "Prof." Russell Smith, read, John Russell

Smith.-W. STAVENHAGEN JONES, 79, Carlton-hill,
N.W.

made with a cast-iron outer case, in. thick, 6in. "Logarithms," B. Tauchintz, Leipzig (Eng. Ed.),
internal diam., and 14ft. long. At the one end it 4s. (?) about the most complete set of tables. Logs.
should be made with an internal flange, through of Nos. 1 to 100,000 to 7 places; first 6° every
which should be a hole cast for the exhaust-pipe. second; other 39° every 10 second, also to 7 places.
And this should be (not 2) the size of the existing-BOILER INSPECTOR.
pipe), 34 inside diam., and of wrought iron, so as
to give ample area for the waste steam to act on.
The sizes I have named will allow about an annular
space of lin. all round. There should be one gland
only on the central pipe. The other end is best
fixed by a pair of locknuts on the internal tube.
exhaust-pipe would, of
The end of the
course, require diminishing socket to couple
it to the present piping. On the cast-iron
outer case let there be two bosses cast on, to take
the feed-water inlet and outlet. So much for the
feed-heater. For the heating arrangement I should,
at the end of the feed-water where the exhaust
leaves it, have a special casting made to allow of a
hinged valve being inserted, so that the whole of
the exhaust could be sent through the piping in the
zoom to be warmed, or cut off entirely from there
and sent as it now goes. This will enable you to
prevent over-heating the room, and yet add but
little extra back-pressure on the exhaust, and
further still prevent the possibility of closing both
outlets for the exhaust. If you want any further
information or advice you are most welcome to it.

-SUNLIGHT.

[44781.]-Praxinoscope.-If the number of mirrors and figures are equal, the figure will appear to stay in the same place. If a boy ruuning, for instance, is represented, the number of figures should not be a multiple of the number of glasses. Attention to this point will insure the figures appearing to progress round the instrument. GLATTON.

[44784.]-Railway Queries.-1. "V." will find some particulars of N. E. R. "singles" in Vol. XXX., p. 265. 2. The distance from Glasgow (central) to Kilmarnock is 24 miles 12 chains. I think that the distance from St. Enoch's-square -station is much the same. Assuming such to be the case, the speed is a little over 41 miles per hour. The Kilmarnock and Glasgow line via Barrhead is the joint property of the C. R. and G. and S. W. Railway Companies. The distance via Paisley, &c., is about 33 miles. 3. How is it that speeds of 75 miles per hour can be attained down Beattock Incline? Well, that somewhat high speeds are got down an incline, falling 1 in 75 for six miles and 1 in 84 for four miles, is not at all surprising, as drivers find it a convenient place for making up lost time. As to the authenticity of these speeds, I may say that the only persons who disbelieve that such (aye and even higher) speeds are attained down this incline are those who know nothing whatever about it. They are a fact, and don't require to be attested by official statements and the like. Indeed, no later than last week a train covered the distance between the Summit and Beattock, stopping at Beattock within nine minutes. This, in my opinion, beats even the instances mentioned by "H. J. A." (18852). There is another story going to the effect that a Perth coupled engine went down in seven minutes. This was about the beginning of June. I cannot, however, vouch for the truth of it. It created quite a furore at the time. Does "Perth" know anything about it? There are four, not two, trains which do not stop at Beattock, going south. "H. J. A." has forgotten the 10.17 and 10.40 p.m. ex-Carstairs.-CARSTAIRS.

[44806.]-Jet-Working.-The tools used for turning jet are bevelled from both sides like a turner's soft-wood chisel, only they are held with the edge horizontal, and scrape rather than cut. Their edges are very thin and keen. A small gouge, also bevelled from both sides, is used for roughing out. For polishing, use first fine emery-cloth, then charcoal-dust, and softsoap on a flannel. Finish with the same, only adding more softsoap. Sometimes rottenstone on the hand or flannel is used as a finish. No heat is required.-GLATTON. [44811.]-Crank-Shaft.-"L. W. S." should rig up a pair of shear legs, or, rather, three. Three poles are tied together at the top and secured from slipping at bottom, and the pulley-blocks suspended gipsy kettle fashion.-GLATTON.

D

vessel.-CHEMISTIANA.

[44923.]-Decolourising Agent.-There is an error, I believe, in "Dunrod's" reply to this query. "Sulphide or bisulphide of soda" should read sulphite or bisulphite of soda. Brewers, however, use generally bisulphite of lime, made by passing a current of sulphurous acid into a solution of slaked lime. The sulphurous acid is obtained by heating oil of vitriol and charcoal in a wrought iron 144928.]-Artificial Leg.-The reason the leg [44861.]-L. and N.W. Engines.-The date grazes your skin is that the joint is not exactly in the centre of your knee-joint. This is most imof Pheasant (263), is not May '63, but May '79.-portant as regards comfort. I am not sufficiently HENRY T. ROBERTS. well acquainted with the mechanism of artificial [44865.]-Air-Pressure from Fall of Water.-limbs to say much more; but I should say your In view of the fact that you have an abundant supply spring is too weak. I would try a spring in front of water at a good pressure, I should advise you to in addition to that behind. Do you find the toe construct an inspirator something like an injector. drag on the ground in coming forward? If so, I Suppose you have an annular jet of water, say, should be inclined to put a connecting-rod from lin. outside, playing into a conical throat like thigh to hold toe up when leg is bent.-GLATTON a funnel, the contraction being a little larger than the outside diam. of the air-jet, and then carry a short piece of pipe into a chamber, from which there should be two outlets, one waste-water, with the outlet-pipe carried up to a height sufficient to balance the water-pressure; and on the top of the chamber an outlet for the air. The chamber to be of good size, so as to act as an air-reservoir. The action is, that the jet of high-pressure water carries down with it a film of air, which cannot get back again owing to the construction at the throat. But this air, which is here carried down inductively by the dashing of the down jet into the air-chamber, disengages the air which collects, and is drawn off as required. Mr. Fletcher's automatic blower and aspirator, mentioned by another correspondent, would not supply more than about 6ft. or 8ft. per hour, at least, that is the best I can get from mine with a splendid water-supply. But that is very ample for ordinary blowpipe work.-SUNLIGHT.

for the

[44904.]-Warming Church.-In reply to your correspondent, Thomas Stone, the best stove for the purpose is the "Hygienic Ventilating Stove," which both warms and ventilates at the same time, and with a great economy of fuel. Some of them can be seen at the Islington Workhouse, Upper Holloway, London, or the master, Mr. Tustinmuld, will give his experience of their use in that Institution. Illustrations, &c., could be given I know, but probably would not be admissible in your columns.-Č. A.

[44911.]-Wrought Riveted Girders.-It would depend on the arrangement and dimensions of the said superstructure.-BOILER INSPECTOR.

[44918.]-Lever of the First Order.-Add the weight of the 2 boys, 15 stone, and the man, 12 stone, together: this makes 27 stone. Now divide the 20ft. plank into 27 equal parts, and let the boys have 12, and the remaining 15ft. let the man have, and they should just balance. To prove it, multiply the weight of man and his length of plank together, and then the weight of boys and their length together, and the two sums will be equal. WORKING TOM.

=

a

=

540

=

=

=

=

[44918.]-Lever of the First Order.-Taking
this question theoretically, the point of equilibrium
is found thus: Let a equal the distance of the
point from one of the ends, say, the man's,
15, 20ft., 12.
; then 20 (15+12)= 540 total
leverage; and 15a+ 12 (20 - a) leverage of
15a+240 + 12a 54027a
the parts
300, and a = 11 1-9ft.; hence, the portion next
the boy's 88-9ft. Or, by "rule of thumb,"
thus: The united weights = 27; the boy's 15-27ths
or 5-9ths of this weight; then, of course, one can
see they only require 4-9ths of the length or weight
of the plank = 88-9ft. in order to balance the other
end. But practically this will not be the distance,
as "W. H. B." states the question; for the com-
bined weights of the boys may be taken as acting at
a point about a foot from the end of the plank, and
the man half a foot from his end. This would make
the length of the plank in the above calculation
only 18 ft.-J. DOHERTY.

[44920.]-Injector Pumps.-It is very import-
ant that the jet of steam should shoot exactly
through the centre of the contracted part of an
ejector. Probably, in so rough a form as this, the
pipe shown in dotted lines on your sketch was not
perfectly central, and the steam struck the sides of
narrow part, and lost velocity before it had time to
do its work. I am much interested in this subject,
and wish some other correspondents would come
forward with their experience, as "Hermes" has
done, and, if possible, would explain the mode of
properly proportioning them.-GLATTON.

[44831.]-Strength of Boiler-tubes.-The following is a very good approximate formula, and one that I think will thoroughly answer "J. W.'s" TX C. P= requirements:-P = bursting pressure in lb. ; T = thickness of shell in sixteenths; D= diam. of shell in ft.; C = = a constant being 1,097 for single riveting, wrought iron; 1,372 for double riveting, wrought iron. Example 7ft. diam., in. plates, double riveting: P [44922.]-Force Pump.-If of the common pattern of wall-pump, you might easily replace the 294. Factor of safety = 5 = safe working-pres- foot-valve in pump-cylinder yourself, which sure of, say, 60lb.-BOILER INSPECTOR. would probably mend matters. It is cut out of [44833.]-Logarithms.-You will find Pride's one piece of sole-leather, and the brass or lead "Mathematics" (Simpkin, Marshall, 5s. 6d.) very weights taken off the old one are fixed on the new useful for the computation of common or Naperian valve. In fixing it, place the rough soft side of logs., and I think Dr. Bruhn's new manual of the leather downwards.-GLATTON.

=

3 x 686
7

=

[44928.]-Artificial Leg.-On examining diagram, it must be too heavy and weak to stand ordinary walking. I don't wonder at the skin

being taken off under the knee. In the first place,
I should advise "One in a Fix" to make the first
socket of thin pigskin, as it is "porous," to fit the
leg properly, using brown paper for the pattern.
Second, make a nice padding with two pieces of
chamois leather and best curled horsehair, stitched
together in four vertical rows, having two rows of
stitching about in. apart down the middle, to clear
the shin-bone. The horsehair is pushed in after
through suitable holes, which make it plump and
soft. The socket F must be cut off more square,
and have a piece of good, light sole-leather stitched
round the top with waxed thread, the top coming
next the knee tapered to a knife-edge, and about
lin. wide, to form a good bed for the other part of
leg, which must be made shorter, as the piece
stitched on to socket F will rest on the top of ex-
ternal leg-piece. The lacing-up is right. I should
make the foot of all willow, same size as the
natural foot; across the bottom of toe-joint cut out
a piece and fit in a good thin sole-piece of leather,
3in. wide, and fix with brass screw, and finish off
smooth flush with the sole, the top of joint cut out
like a V, to allow the proper action in walking; in
the top part of V fix a piece of rubber, gin. thick
and the full width of foot, to push the toes down,
which gives a good spring in stepping forward
with the good leg. The ankle must be exactly the
same height as the good leg, but made with a stop-
joint, which allows enough action, and no more
than is required, which can only be understood by
drawings. The steel bars are riveted with four
rivets to both sides of outside socket, similar to
sketch. In the leg I made there was no thigh-
piece; the wearer simply pushes in the stump, like
a Wellington boot, and walks away, using heel and
toe without any flop. The amputation was at the
ankle-joint, which gives more power; and part of
the bearing is taken on the end of the stump.-Ex.
The difficulty
[44939.]-Brass - founding.
"Young Ireland" has met with in brass-casting
is capable of a very easy solution. In the first place,
his moulds are evidently too wet, as the splut-
tering of the metal when cast shows. Moulds
cannot be too dry for brass.
place, he should throw his black sand away and
mould his brasses in new sand, without any admix-
ture of coaldust; cores should also be made of new
sand, properly vented, and well dried. After
moulding, dust the moulds either with flour-
whiting or limedust, and if they should be too
wet thay can be dried by means of a red-hot plate
being placed over them before they are closed for
casting. Try the following for a
common soap, oz. quicklime, oz. saltpetre;
mix into a ball, and place in the crucible when
lifted out of the furnace. This is sufficient for
about 50lb. of metal. Let your metal be hot, so

In the next

46 flux":-loz.

[44966.]-Hydromotor.-A description of this appeared in the reply-columns of this journal (see P. 70). It is a revival of the idea mentioned by the Marquis of Worcester in his "Century of Inventions," as also of Savory's pumping-engine, so-termed; and I think I can add but little to the description quoted. It is, of course, free from moving parts comparatively as a 'screw-engine; but I very much doubt whether it will ever come into general use. For instance, the water-cylinders must be of large diameter, and must also be of sufficient strength to stand the pressure, and there[41958.]-Fossils.-London-clay fossils can be fore would require to be a little stronger than the found at Sheerness, Faversham, and other places boiler. It is also likely to cause a small vessel to be near the mouth of the Thames. Fossil fruits, more tender and crank than if filled with teeth, reptiles, and fish are found there. Mr. a reciprocating engine, and from the fact that one Shrubsole, of High-street, Nile-town, Sheerness, cylinder is full of water whilst the other is nearly would, I have no doubt, give you information of empty, the balance of the weights of the boat would the exact place to find them. He has an interesting be in a state of constant disturbance, and from collection of these fossils.-P. MARTIN, Chipstead. these two main points I should not consider the [44959.]-Silvering Gilded Watch Face and hydromotor very suitable for yachts or any small Barometer." No Sig." will save his time, pro- craft. When you say what form of engine will perty, and temper by taking his goods to a watch-occupy the least space and be lightest for the maker, jeweller, or optician. However, polish the power, you open a great field of idea. As I like as surfaces chemically clean, procure prepared silver, and apply it with the naked hand, salt, and water. Dry the goods, paint the figures, heat in front of a clear fire, about 160° Fah., then with a flat brush paint the surface with transparent varnish, taking care only to touch the surface once. Allow the

n

stove-chamber and the fume-pipe, before the light
is applied to it, an explosion, not perhaps without
danger, may result. This is obviated, at the outset
by applying the light at the same instant the gas
is turned on. As I sit writing this letter, 5ft. away
from my stove, I feel the constant and gentle
warmth emitted from it, and inwardly thank the
inventor for the comfort I experience.-ALFOJOE.
[44985.]-Gas Fire in Bedroom.-There are
plenty of manufacturers who supply burners that
can be fitted into the grate now in your bedroom,
which, when fitted, can be filled up with asbestos,
or pumice stone, which becomes quite red-hot
when the gas is lighted. And there is another kind
made like a sheet-iron basket to fit into the grate,
which can be lifted out and placed into any other
bedroom grate, and by connecting it to the gas
with a rubber tube, you are then ready to light
up. I have had one of these in use for some time,
which I find very convenient. If "H. O'B."
will advertise his address in 6d. column, I will send
him drawing and prices of the above.-JOE BLAIN,
Carlisle.

[44987.]-Carbonic Acid Gas from Chalk.100 parts of chalk, if it consisted of pure carbonate of calcium, would require for exact neutralisation 98 parts of pure sulphuric acid or oil of vitriol; the quantity of commercial vitriol required will depend on the strength of the vitriol. The querist can readily ascertain this by taking the density with =: Twaddel's hydrometer. These can be obtained for 2s. 6d. each. Having obtained the density, refer to tables to be found in most chemical books of a technical character. One pound of pure chalk will yield 23 6-10ths gallons carbonic acid gas at normal temperature and pressure. "One volume of any gas at 0° C., becomes 1.003665 volume at 1o C., or 273 volumes of any gas at 0° C., become 274 volumes at 1° C., and 275 volumes at 2° C." (see Thorpe's "Chemical Problems," 1s. 6d., published by Macmillan).-CHEMISTIANA.

=

=

held firmly between the first three fingers of the
left hand. When the spring is all wound up, the
pallet is reversed to keep from running back; the
barrel is then suddenly put over the spring. 2.
The lever over the tool is for holding springs full
wound up that have the hook in the end of the
spring, and not in the barrel. This lever is old-
fashioned.-W. M.

[44995.] Mainspring Winder. Fix the
winder in the bench-vice, and if for a lever or
verge-spring, set the clickspring underneath so
that the winding arbor will turn under and over,
to and from you. If for a Geneve spring, set the
reverse way for the majority of cases. Hook the
inner coil of the spring on the arbor, and, if for a
lever or verge, guide the spring, and hold with the
left hand whilst you wind with the right. If the
spring is fitted with a barrel-hook, bring down the
"lever," and set it against the hook on the now
wound-up spring, which will thereby be securely
held, coiled up, ready to slip to its place in the
barrel. In fitting a spring in this way, care should
be observed that the coiled spring is only slightly
less in diameter than the barrel, just enough to
free the hook. If allowed too much recoil, the
hook may be snatched off, or the spring injured at
the riveting, by the strong jerk it receives when
the hook catches in the hole in the barrel. With
a spring having no hook, the "lever " is not needed.
-ALFOJOE.

[44996.]-Tithes.-"A Member of the Anti-
Tithe League" will find in Hume's "History of
England," Vol. I.. how tithe was first imposed in
England by King Ethelwulph at the instigation of
the clergy. "The payment of tithes before his
reign had been voluntary, and was considered a re-
"Book of the
ligious obligation" (Southey's
Church"); see statutes at large, 29 Hen. VIII.
Tithe was commuted for money by the Act for the
Commutation of Tithes in England and Wales,
6 and 7 Will. IV., c. 71, 97 clauses, 1836.-
SADDLED.

[44987.]-Carbonic Acid.-The action of pure sulphuric acid (vitriol) upon pure calcium car- [44999.]-Self-Feeding Fountain.-I regret bonate (chalk) is represented by the equation to have to tell "O. F. C. C. O." that it is simply CaCO3 + H2SO CaSO + CO+ OH; which an impossibility to do what he proposes. If it means that 100 parts by weight of calcium car- were possible, not only would he have attained perbonate are completely decomposed by 98 parts of petual motion, but still more, he would have sulphuric acid, yielding 44 parts by weight of actually discovered a mode of obtaining power "carbonic acid gas." As the chalk and vitriol are which so far would be totally against all natural not likely to be pure, you may use 1lb. of chalk to laws. If he will look at the question again, he llb. of vitriol, or 9 fluid ounces by measure. Now, will surely see that the pumps to lift up the volume as CO, occupies two volumes, 1 litre of it weighs, of water necessary to actuate the water-wheel at 0° and 760mm., 1.97 grammes, and at the usual would exactly absorb the power given off by that temperature of 15° (= 59° Fahr.), 1 litre weighs wheel, leaving nothing for friction. And further 1-87 grammes, or cubic foot weighs 52.97 still, the pumps must actually lift not only enough grammes 1171b. nearly; so that the gas arising water to drive the water-wheel, but to supply the from 1lb. of chalk will occupy 441173-75, fountain-jet. In any case it would be a total or 3 cubic feet. "Carbonic acid gas,' "like all impossibility; but to do so in view of the extra other gases, within limits, expands 1-273rd of volume due to the discharge of the jet, is making its volume at 0° C. for each degree above that the impossibility still more glaring, to say the least temperature; so that 273 cubic inches at 0° of it. This, in some respects, is a parallel to the C. become 274 cubic inches at 19 C., 288 proposition made by a querist at page 507, Vol. (or 273 +15) at 15° C., &c. Full particulars as XXXI.-SUNLIGHT. to expansion of gases, and as to chemical action [45000.]-Toning Bath. and the proper quantities, are to be found in any better not try to doctor his bath in such a condiwork on chemistry. I recommend you to buy Chambers's shilling book on chemistry, and write tion. It seems to be an acetate bath, and with some people this will never act well (AuCl, or again if you do not understand my explanation.-gold-trichloride is not so very expensive), so throw it in your waste-tub. For a good bath try the following: Tungstate of soda, 2 scruples; goldtrichloride, 2 grains; boiling water, 16oz. fluid; use when cold. This will only last for one batch of prints, say, 170 C.D.V.; then make new bath, and save the old with your other gold waste. WILLIAM PECK, Hayward's Heath.

LEWIS ARUNDEL.

[44990.]—Exhaust.-The exhauster is usually a modified form of fan, in which the gas is, as it were, dealt with something after the fashion of a

scoop-wheel lifting water. Generally they are made with a series of blades or fans, which work, as it were, into the large main pipe from the retorts, the upper part of the fan being carried in a casing, carried, as it were, on the top of the main pipe. To properly describe such would require a sketch, which I

send herewith, and which will give you a better idea of the arrangement than a mere description.-SUN

LIGHT.

[44995.] Mainspring Winder. - 1. The winder is screwed in the board-vice; the outer end is not put in the barrel first, but the inner coil is forced over the projecting pivot; the handle is then turned by the right hand, the spring being

"W. E. K." had

[45000.]-Toning Bath.-As it is impossible to
make sure of what should be done, the best way by
far is to avoid any tinkering with the toning bath,
and to make a new one up at once. The old one
may be easily made to give up any gold held in
solution by adding to it a little of the green sul-
phate of iron crystals, which will throw down the
gold as a purple deposit, which may be washed and
re-dissolved in aqua-regia, thus again forming
chloride of gold. But don't waste time in trying
As to a formula for a
to doctor your bath.
new bath-if you want purple tones, use chloride
of gold, 1 grain, boiled with a little precipitated
chalk until neutral, and then add 30 grains of acetate
of soda, and water to make up to 8oz. But this
solution must be 24 hours old. For architectural
subjects, the same quantity of gold neutralised as
described, and 20 grains of phosphate of soda and
8oz. water. This won't keep, mind, and the prints
tone very rapidly.-SUNLIGHT.

[45002.]-Darkening Oak. - The best and
cheapest method is to fumigate the work, either
before it is fixed, by placing it in a chamber or
room made airtight, or after the work is fixed in
its place, by making the room airtight. You will
require for a room, say, 20ft. by 15ft. by 11ft.,
about a quart of liq. ammonia 880, costing 2s. Put
this in a dish, and leave it in the room for twelve
or fourteen hours. Should the work not be dark
enough, you must either put in more ammonia or
leave the room closed for a longer time. When

you apply the ammonia with the brush, it not only raises the grain of the wood, which has to be rubbed down again, but it also stains the end wood very much darker than the other parts. The tighter you make your room or chamber, the less ammonia you will require for fumigating.-CAB.

or

[45006.]-Chemical.-With apologies to Mr. Allen, I may tell "W. S. F." that the quantivalencies and atomic weights of the metals named are:-Cerium, 92; didymium, 96; erbium, 113; lanthanum, 93; thorium, 234; Yttrium, 61.7. Cerium is dyad and tetrad, the others are all dyads except thorium, which is tetrad. All these metals are precipitated as hydrates from their solutions NaHO. These metals by AmHO, KHO resemble Al most, but uranium is clearly allied to iron. Brick red hydrate, pp., by AmHO, and black sulphide by SAm2, green carbonate, green reducing soluble salts; so its quantivalence, like that of iron, is dyad and pseudotriad, and its At. Wt. 120. You are no doubt acquainted with the curious uranyl nitrate and uranyl sulphate of formula U2O,, N2O, and U2O,, SO3, which are not the formule N2O, anomalous compounds, as show. - LEWIS (U2O)O" and ́SO,(Ú,O,)0" ARUNDEL.

[45009.]-Liquefaction of Oxygen and Hydrogen.-M. Cailletet liquefied oxygen on the last day of December, 1877, and M. Pictet on the 11th of the January following. At the moment of liquefaction the pressure in the apparatus was no less than 505 atmospheres in conjunction with 140 degrees of cold. Hydrogen was liquefied at the same time under a pressure of 650 atmospheres, or 9,555lb. on the square inch.-SUNLIGHT. Small [45010.]-Erecting Engine. To "SUNLIGHT."-You will only be able, I see, to get a stroke of 24in. Piston must be in. thick, with either a brass or cast-iron ring, or a hemp packing; piston-rod should be in. diam. and 4in. long; bed-plate 14in. by 4in. ; motion bars 44in. long with lin. by surfaces in. wide. Guide blocks in. Connecting-rod must be of the length to suit the distance of the crank-shaft from the motion bars. You do not say the width of the bars between the steam and exhaust ports; I am therefore unable to tell you the size of valve, &c., but will do so on getting size of bars. The valvebox, I would say, is very small for the size of engine. See also page 192, Vol. XXXI.—SUNLIGHT.

[45013.]-Electric Light for Workshop.-I very much question whether, from the present arrangement of your shop, the electric light could be advantageously applied. In fact, I think not. At any rate, you must not forget that the dynamo machine would cost you something like £250 to begin with, and it would be quite useless to think of making one, as it is a matter requiring special knowledge. If you bought a machine you might use the "Swan" lamp; but I doubt whether in the long-run you would do much good with it.-SUN

LIGHT.

[45016.]-L. and N. W. R. Engines.-Trent, August, 1864; Condor, June, 1877: Planet, January, '66; J. Ramsbottom, March, 72; The Queen, April, 72; Blenkinsop, August, '73; Euxine, October, '74; Eolus, October, '51; Buffalo, March, '75; Bee, July, '64; Trevithick, August, '53; Airey, April, '68; Marlborough, November, '66 Sisyphus, May, '68: Livingstone, May, '68: North Western, August, 73: Pioneer, March, '72: Sultan, September, '61; Newcomen, May '66: Byron, November, '66; Famont, August, '70.-DIOMED.

[45016.]-L.N.W. Engines.-Herald, October, 1858; Trent, August, 1864: Condor, June, 1877 Councillor, October, 1861; Planet, January, 1866; Eolus, October, 1851; Airey, March, 1868; Atlas, November, 1874; Marlborough, November, 1866; Livingstone, May, 1868; Pioneer, April, 1872 Sultan, October, 1851; Newcomen, May, 1866: Columbine, October, 1851. The following four, I am sorry to say, I only know the year they were built:- John Ramsbottom. 1872; The Queen, 1872; Sisyphus, 1868; and Latona, 1854. I hope the above will be of assistance to you.

FORTUNA.

[45016.]-L. and S.W. Engines. - Herald, Oct., '58; Hardwicke, Aug., '73; Trent, Aug., '64; Condor, June, '77: Councillor, Nov., '61; Planet, Jan., '66; John Ramsbottom, March, '72; The Queen, April, '72; Blenkinsop, Aug., '73; Eolus, Oct., '51; Buffaloe, March, '75; Trevithick, Aug., '53; Airey, April, '68; Atlas, Nov., 74; Marlborough, Nov., '66; Sisyphus, May, '68; Livingstone, May, '68; North Western, Aug., '73; Pioneer, March, 72; Sultan, Nov., '61; Newcomen, April or May, '66; Byron, Oct. or Nov., '66; Eamont, Aug., '70; Columbine, Oct., '51; Latona, April, '55.-HENRY T. ROBERTS.

[45027.]-Photographing the Moon.-If the eyepiece of the telescope be removed and a rapid symmetrical be inserted in its place, or a little, farther away from the focus of the objec:-glass you will then have converted your instrument

UNANSWERED QUERIES.

into a photo-heliograph, which will enable a good-
sized image of the moon to be photographed. This
instrument must be furnished with clockwork
motion, for any exposure exceeding a couple of
The numbers and titles of queries which remain unan.
seconds will be fatal to sharpness unless such awered for five weeks are inserted in this list, and if still
provision be made, and with the most rapid unanswered are repeated four weeks afterwards. We trust
plates considerably more than this will be neces- our readers will look over the list, and send what information
sary.-BABOON.
they can for the benefit of their fellow contributors.

Since our last C. S. Coach has replied to 44558; Ele

wick, 44576, 44603; Guide Yoke, 44611, 44662.
Solar Engine, p. 557.

44398.

44401.
44404.

Carlisle Cathedral, 557.

Black Bronze, 557.

44411.

Violin, 557.

44418.

Cranes, 557.

44419.

44431.

Dressing Horse Hides, &c., 557.
Mending Asphalt, 557

44432.
44433.

Specifications Wanted, 557.

Gas-Engines, 557.

44436.
44438.

44453.

Electrical Insulator, 557.
Flute Mouthpiece, 557.
G.W.R. Engines, 558.
Biscuits, 558.

44455.
44457.

Chloride of Zinc Battery, 558.
Cutting Diamonds, 558.

44461.

Water Engine, 558.

44463.
44464.

Annealing Sheet Nickel, 559.

Chloride of Zinc Battery, 558.

44469.

Legal, 558.

[45028.]-Permanent Ink - Photographs.Photographs in half-tone cannot be printed in the ordinary printing-press, but require apparatus of the lithographic or copper-plate type. Blocks, however, are prepared by photography from linedrawing for typographical work. By the process indicated, when employed in the reproduction of photographs from nature, the gelatine cliché takes the place and receives the treatment of a lithographed stone. very similar process is also emplayed in preparing blocks from line and such-like drawings, an electrotype being taken from the gelatine image and backed as usual.-BABOON. 44450. [45031.]-Malt-Puddings. Sixty years ago barley-bread was eaten largely by the poor, but 1 never heard that it was considered as wholesome as wheat-bread. There are various opinions about malt being nutritious, and malt-biscuits are sold. I think there is very little malt in them. Common flour will not make good cakes or puddings. Vienna and best biscuit-flour are excellent and more economical for both. For pastry I use equal proportions of each, and the tarts and pies are extremely nice and good-looking-in fact far better than any I ever ate in first-class hotels. In cookery, as in some other arts, all sorts of messes are made and contrivances adopted to hide the original sin of the whole business-bad or stale material as the foundation.-AN OLD LADY. [45032.]-Improvement in Rowing-Boats. -I fail to see how "Strong Legs" gets a longer, effective stroke in a boat fitted with his "improvement." In the usual type of boat, fitted with a long slide and swivel rowlocks, the oarsman gets as long a stroke as is of any use. If during his slide aft the rowlock be moved forward the oar will be inclined at such an angle to the boat as to be almost entirely useless. It must be remembered that the oar does most work when at right angles to the boat's length, and it is useless to go beyond a certain angle fore or aft. I should also fancy that the sculls must be inconveniently long. And how about working the slide? With the usual arrangement, it is necessary to have the slide well oiled, because a very little thing will check the -PHOTOGRAPHER. slide and cause a roll. What, then. can be expected if we have to work a series of levers con-harmonium, by Cramer, with six rows of reeds. In the [45038.]-Perpendicular Reeds. -I have a large nected to the rowlocks as described? I fancy it Musette stop, the reeds, instead of being laid flat on would be difficult to keep on the seat, unless a soft the reedboard, are placed perpendicularly in a narrow piece of cobbler's-wax was placed thereon before division and fixed to the partition. Can anyone explain the oarsman seated himself, and then what about the theory of this arrangement? Also, must the entire getting up? As an oarsman of experience, I may or make a dumb one speak!-MUSETTE. row be unscrewed and removed to replace a broken reed say that if the usual arrangement is properly used, i.e., the water caught sharply with the arms straight out, keeping them so to the end of the slide, the legs have as much work as they can get through.-W. B.

[45034.]-Connecting Chimneys. - Let me advise you not to connect your chimney. I will give you good reasons against it. In the first place, you will simply make your tall chimney smoke instead of the short engine-stack, and this will simply shift, but not mend, matters. Then, again, suppose you connected the two chimneys by an irou flue, you would still be losing, as the smoke you now see from the engine-stack, even if transferred to the kiln-stack, would still be so much coal burnt to waste. Far better go to the root of the evil at once, and deal with it there. Consume your smoke at the boiler at once, and you will not need costly connections. You will also save coal, and, so long as you do not make a smoke, no authorities can compel you to connect the two chimneys. When I see a chimney vomiting out clouds of black smoke, I always wonder why owners of steam-power prefer to entirely waste a good percentage of the fuel, and, at the same time, set up a nuisance, when the smoke can be burnt, utilized, and used to advantage, and avoiding pollution of the atmosphere. The consumption of smoke is easy enough if persons will only see to it But, unfortunately, owners too frequently trouble themselves too little on the question, and hence we see the clouds of unburnt and wasted carbon floating away for a long distance. No, friend "Treadle," apply the cure at your boiler, and don't go to the trouble and expense of making a chimney that now does not emit smoke a smoke-emitting nuisance, as it would be if you connect the two.-SUNLIGHT.

(45035.]-L. and N. W. Engines.-Giffard (680), Thunderbolt (409), Wm. Barker (779), Sirocco (1153), are Webb's 5ft. 6in. coupled. Shark (2159), Kestrel (852), Zeno (401), Memnon (736) are Ramsbottom's 6ft. coupled. The Queen (1213), Hector (304), Pioneer (1212) are Ramsbottom's 6ft. 6in. coupled. Clyde (833) is a 7ft. 6in. single, and Crane (137), I believe, but am not certain. Autocrat (321) is a 6ft. single outside cylinder engine.-DIOMED.

the moon there given, to identify any of the objects named. This is my difficulty- When the moon is four or five days old, I cannot identify the craters on her surface with any of those on the map in Celestial Objects." They appear to me altogether unlike. The map there given seems to be a map of the full moon; and even at the full, I cannot make much of it. Are any maps of the moon published showing the craters, reas, &e., visible for every day of her age? Telescope used: a 2 aperture.-A POOR STUDENT, AND LOVER OF THE "ME

CHANIC.

(45046.]-The "Rocket."-Could anyone tell me where I could find scale drawing with full details of valve gear, &c., of Stephenson's locomotive, the "Rocket "the original, not the improved article 1

CHASM.

[45047.1-Steam-Pipes.-At present I warm workrooms with exhaust steam. Being about to put in a gasengine, would it answer if a pipe was taken from top of boiler and returned down and connect d at the lower part below water-level of boiler? And, would any valves be required?-DOUBTFUL.

[4:048.]-Chemistry of Soap.-Can Mr. Allen, or any other reader, inform me if a dark resin is stronger than a pale resin? Does it contain more sylvic acid! And, will it produce more soap?-F. H.

[45049.1-Carmine Paste.-How is carmine paste made, and what is the best method of bringing it into solution? I am informed that ammonia and cream of tartar is used for dissolving it.-F. H.

(45050.)-Papermaking. What are the colouring matters used for producing Caledonian and silver greys! -PAPETIER.

[45051.]-Model Loco.-To "E. L. P."-I am much obliged to "E. L. P." for answering my query. Will he kindly inform me how to fit the tubes and firebox! Will the boiler, if fitted as he recommends, drive a pair of cylinders in. bore, 1in. stroke? I may state that I have allowed only 3in. between underside of boiler and ground.-NoVICE.

-

145052.1-Watch Finishing. Would some of "ours" kindly say how the pillars are finished" Also, the outer rim of the plate, the work being held in the mandril.-GUYOT.

[45053.]-Pancratic Eyepiece Focus.-I have an astro. telescope, to which there is a pancratic eyepiece consisting of a couple of tubes screwed together. The cuter one has two small lenses and the astro, eyepiece slides in it; the inner tube slides in the tube on which the rack for focussing acts, and there is a diaphragm to that, if not correct, I may be told so. Now, how should contract the aperture. I mention these particulars so this be focussed for best effect? I can only get it in focus by rule of thumb, but would like to know the proper system to go on. I may mention that when the astro, eyepiece is just entered in the tube, on looking through, it shows a quanity of blueish-looking airbubbles. but when pushed further in, these disappear, 100 and, after some chance adjustment, a distinct image is produced.-SUBSCRIBER.

H2SO4..... 40°/
HNO3
50
H2O 10/

To "SUNLIGHT," OR

best method for cleaning after use, and say if it is [45054.1-Cleaning Firearms.-Please give the detrimental to leave a day or two without cleaning. Also, please say if the Martini-Henri is satisfactory in small rook rifles. Or, is there a better form?-SUBSCRIBER.

[45055] Organ. To MR. DRESSER. — Will Mr. Dresser kindly inform me in anticipation of his article on [45039.] Gas Stoves. "Action," promised at p. 414, Vol. XXXII., (1) whether OTHERS.-Will you be kind enough to inform me if I can both kinds of action can be used together in the same alter my gas-stove (which is simply a Bunsen burner in-organ without interfering with one another? And, if so, side a sheet-iron casing) so that it will give more heat? (2) whether the pipes on each kind of windchest must be And, also, is it possible to do away with the fumes that arranged respectively in the same order? I wish to ise from it, there being no chimney! I am shut up know this as I desire to use one of the windchests there with it for ten hours at a stretch, and shall be glad to described for an Open Diapason front, ornamentally arranged. Ishould add that my organ was too far advanced improve it if possible.-A. G. at the time the above-mentioned article appeared to admit of my adopting altogether the kind of windchest there described.-C. W., S.

(45040.)-Dissolving Paper.-What (if any) acid or process will effect this!-C. O.

[45041.]-Engine Query. Would " Sunlight" kindly assist me in the following ?-I am working a pair 3ft. stroke, 32 revolutions per minute; low-pressure of McNaughted beam engines. H.P. cylinders, 28in. diam., cylinders, 32in. diameter, 6ft. stroke; point of cut-off in h.p. cylinders, 18in. ; initial pressure, 50lb.; indicated power, 450 h.p. I should be deeply obliged' if "Sunlight" would kindly inform me what per cent. I should gain by raising the pressure to 90lb. Also, please state finding out the sum in plain figures, as I do not underwhere the point of cut-off would be, and the rules for stand algebra.-NOVICE.

[45042.]-Buroing China - Paintings.-Would practicability of erecting a kiln suitable for burning a any readers be obliging enough to inform me as to the few small articles at a time, as I am in business and situated inconveniently enough to the potteries? ARTISTS' COLOURMAN.

working at a 3ft. stroke, forcing water 140ft. high. Will [45056.1-Pumping.-I have a 6in. force - pump to force it still higher by adding on an air-chamber? any of our kind readers please tell me if I shall be able And, if so, at what length should the air-chamber be to be of the greatest service ?-A YOUNG PITMAN.

[45057.)-Speeds of Boring.-Would "Sunlight," or Mr. J. H. Evans, kindly say at what speed in feet per should travel! -Soft wood, such as pine, &c.; hard minute (for boring and turning) the following substances wood, such as oak, ash, &c.; wrought iron; cast iron; steel; brass.-INQUIRER.

(45058.)-Thimbles.- Would someone kindly say how thimbles are made?-E. A.

[45059.]-Medical.-Would Dr. Edmunds tell me how I can overcome an obstinate constipation and an extreme sen ibility to cold, deadness of the fingers in temperaments be believed, am leuco-lymphatic. — B. C. F.

[45043.)-Photography.-Will some of our photo-washing? I have always been well nourished. If
graphic friends kindly give particulars of a screw and
rackwork motion for camera? how it is made and fitted
to allow of the bare board folding? which is considered
back: have made the horizontal swing, but find a
best, screw or rack work? Also, of vertical swing
difficulty in the vertical. And of the reversing frame
for back of camera-how is it made and fitted to
camera? If not troubling too much, a sketch will
oblige
-CRESCENT.

(45044.]-Oxy-Hydrogen Microscope.-I con-
temp ate giving a lecture on marine and freshwater
inierozoa, and shall be very thankful for information
from any who have bad experience as to what apparatus
is necessary to adapt the microscope to an oxy-hydro en
lantern. Any hints likely to be of service to one who
has never seen such apparatus, or witnessed its applica-
tion for illustrations, will greatly oblige-A PROVINCIAL
MICROSCOPIST.

[45045.)-Maps of the Moon.-Will "F.R.A.S.,"
Mr. Webb, Mr. Birt, or any of your numerous astro-
How
nomical readers, kindly assist me in the following?
can I identify the luuar craters ? I possess
"Celestial Objects," but I am unable, from the map of

(45060.]-Fossil Birds in Delabole Slate.The Delabole s'ate quarries in North Cornwall are considered by most geologists to be Devonian, which is far anterior to the age of birds; but I have this day (Oct. 7) seen impressions of two birds and a butterfly on the blue slate. Strange to say, there is no particle of wings in either of the birds, but the feathers appear like cord, very much like those of the Apteryx of New Zealand. Can anyone give an opinion on the above !-CHARLES BARRETT.

145061.]-Three-Throw Pumps.- Will any of our readers kindly inform me if the following figures are correct?-Required to raise 570 gallons of water 100ft. high in one minute. Pumps 12in. diameter by 2ft, stroke at a piston speed of 80ft. per minute. Size of pipes to (vertical engine) to work at to drive above ! Information Also, what size of cylinder, and what pressure will greatly assist-H. H. L.

use.

[45062.1-Oil Stains.- In view of the possibility of "moving," I should be glad to know how to remove

Beats-foot and other oil stains from floor of the "latheroom."-C. O.

45063.]-Iron Mixture.-Will some reader kindly tell me the best cast pig-iron to use to mix with wrought iron, and what proportions in order to get castings fit for turning-V. R. R.

[45064.1-Finding the Moon's Position.-I am at a loss to know how to find the position of the moon with regard to the earth at certain given times to within about an hour. For instance, the moon is full on December 5th, at 5h. 13m., declination at this time is 22° 1'North. To what part of the earth's surface is she opposite at the time of full moon? Again, the moon crosses the Equator December 12, between 23h. and 24h. astronomical time (Nautical Almanac). In what longitude am I to look for her position when crossing the equator? There is not such a thing as a globe to be got in the town where I am, but I have some flat polar projections of the northern hemisphere (outline maps), and I believe it would be quite possible to arrange these so as to represent on them the position of the moon with regard to earth's surface at such times as new, full, when on equator, &c., when she is, of course, in Northern declination. The moon is in extreme N. declination on December 5th at 13h., full the same day at 5h. 13m. Now, it appears to me that at this time she should be opposite India, but whether I am right or not I have no certain means of knowing. Again, I should like to know what is meant by "upper and lower" meridians.-W. L. O., Tzarskse Celo.

[45065.]-Chemical and Microscopical Test of Silk Can any of our readers tell me the best way of examining silk fabrics (1) microscopically, (2) chemically-my object being to ascertain if there is any, and if 50, what amount of admixture of cotton, wool, or other fibre? Also, any information as to the material used in the dressing of silk, and the means of detecting same, would greatly oblige-MERCER.

[45066.]-Astronomical Question.-Will someone be good enough to explain the following passage, which I quote from Croll's Climate and Time" (it refers to Col. Drayson's theory of the cause of the Glacial epoch) ? -"Col. Drayson considers that the pole of the heavens describes a circle round a point 6' distant from the pole of the ecliptic, and 29° 25′ 47′′ from the pole of the heavens." I cannot understand the difference between the two poles. -THETA.

[45067.)-To Mr. Lancaster.-I wish to make an electro-magnet to sound a gong (Chinese) of 15in. diam, and shall be extremely obliged if you will kindly give me a working description of magnet, armature, and striker, and most convenient method of mounting the same to get the best results from the gong. I should mention that it will only be rung once a day at dinner-time, and I Lécianché, small size) that I use for the electric bells in should like to work it from same battery (four cells the house. If this battery is too weak, please say most suitable, as I have several other kinds.-JNO. H. B., Southport.

[45068.J-Heating Railway Carriages with Acetate of Soda.-Will S. A." tell me whether the heater is to have the acetate of soda dry or dissolved in water? I should like to make a small one for my own use at home, and I suppose there would be no objection to my doing so. I suppose the heater should be filled only three parts full, to allow for expansion in heating. I should be glad of any other hints.-M. A.

145076.]-Palpitation.-Will Dr. Edmunds kindly
advise me what to take or how to act? I am about 55
years of age, and for the last twenty years have been a
total abstainer. About seven years ago I suffered from
a like cause, but it wore off in about six months. I have
now been more or less troubled with it for several
months, and I am told it proceeds from indigestion and a
weak heart. I can eat very well; but sometimes, when I
go to bed, I cannot go to sleep for hours, nor keep still in
bed, turning from side to side. I take a good deal of
out-door exercise; of late I have felt at times giddy for a
moment, and have to pull up as if I was going to fall
down. I do not like to have recourse to patent medicine.
I have been recommended tonic wine, hop bitters, and
many other things. I have seen Dr. E.'s reply to No.
19308, but do not know if it will apply to mine.-A SIX
YEARS READER OF "E.M."

readers inform me as to the best means of keeping alive
[45077.)-Water Tortoise.-Would some of our
and healthy a water tortoise I have had sent me from the
continent -AN M. D.

secondary wire, length, &c. Those at the Opéra in Paris no doubt are first rate, and a perfect description would much interest many. I am anxious to know whether that mode, which now seems much used, of connecting a number of microphones in parallel series, and having a large current through them, does away with the grating sound which is so annoying? Can anyone give details of the telephone mentioned by correspondent in Oct. 7th number as used in Paris exhibition?-F. E. T.

CORD.

[45091.] Rendering Cotton Wadding Absorbent.-Can any one inform me how ordinary cotton wadding can be rendered readily absorbent?-Box Ac[45092.]-Silvering Goods by the Electro Process.-"Os" would confer a considerable benefit on a large number of men connected with various branches of the silver trade if he would give a clear demodus operandi, and probable cost of same on small scription of electroplating, chemicals, apparatus, and scale.-GUYOT.

[45093.]-Shears for Sheet Iron.-I should be
glad to know the simplest form of construction of shears
to cut sheet iron, 18 to 20 gauge, easily.-J. W.
[45094.]-Stereotyping.-A note on this subject
appeared in last week's "Scientific News."
Can anyone
give information as to the nature of the quick-drying

[45078.)-Salicylic Acid.-In No. 863 it is stated
that the French Government has lately prohibited the
use of salicylic acid for the preservation of articles of
diet. Will Mr. Allen kindly say what injurious effects it
produces on the health? It is used in this country
for the preservation of wine, about three-quarters of a
troy grain being added to une imperial pint of wine.cement used for the matrix ?—J. W.

ITALY.

[45079.]-Train of Watch.-Will any of "ours" kindly inform me how to calculate the train of a watch when you have only the centre-wheel to work from! I have seen several methods, but they all seem to take the number of teeth and pinions for granted, and from them deduce the number of vibrations of balance per hour. I can calculate that myself. What I wish to do is to calculate the train from centre or any other wheel. Any information would greatly oblige-E. P. A., Horologist.

[45080.] - Barometer by Henry Andrews.-I have a barometer bearing the following name and address "Henry Andrews, Royston." Can anyone inform me if this is likely to be the noted astrologer? And, did he manufacture these articles? Is there a portrait of Andrews in existence ?-J. H. W.

[45081.)-Photographic.-Can any correspondent protosulphate of iron, it is bleached, losing at the same tell me why, if a print, fixed and toned, is immersed in time its blueish or reddish tint and turning grey. And, what the clear remainder of an old ferrous oxalate developer 18, and, also, the red precipitate of the same? -W. E. K.

[45082.]-Double Object-Glasses. - To "ORBERIC Huyghenian eyepiece two non-achromatic convex glasses, VITAL," W. G. P.," AND OTHERS.-In the ordinary when of suitably-proportioned foci, and placed at a certain distance apart, correct the spherical aberrations, and, to a great degree, the chromatic aberrations as well. Is a similar arrangement in any way practicable in the object-gliss! In other words, can two non-achromatic lenses of the same kind of glass, and neither of them a concave curve, be so proportioned and placed as to act as an object-glass, but with the spherical and chromatic aberrations inaterially reduced?-QUERY.

[45083.1-Gas Regulator.-Can any reader of the ENGLISH MECHANIC inform me from personal experience of the advantage or disadvantage of a gas regulator, and whether the saving said to be obtained is worth the outlay, which amounts for a twenty-light meter to about

£41-EYE WITNESS.

(45069.)-Fossils. How is it that Owen, in his
"Paleontology," says that there are no barnacles until
the tertiary rocks, or that they are very scarce? I have
found them in abundance in the Oolite, and I have one
from Carboniferous Limestone. What species of Echini
[45084.]-Distemper.-I want to add a frieze to the
have square spines, also hollow ones! I have one or two
walls of a room now covered with a flat tint in distemper,
from Oolite and Bradford clay. They are not common,
are they! Also, what species have long smooth-pointed more shades, either by hand or by the use of stencil
and propose to do so with the same medium, in two or
spines I have what appears to be a seaweed in Brad-plates. I shall be much obliged if any of your con-
ford clay. Are seaweeds ever found in it? I found a
tributers will kindly inform me what are the materials
stone near Bettws-y-Coed, N. Wales: in shape and out- required, where obtainable, their price, the best kind of
side surface just like a turtle, about 9in, by 7ın. Is it a
card or paper for the stencil plates, and any other hints
fossil at all? And, if so, what?-M. A.
on the process. Is there any small book published on the
subject?-EYE WITNESS.

[45070.)-Soap Frame.-Will any correspondent please state the best method of constructing above either in iron or wood ?-HADRIAN.

[45071.)-East Anglian Passenger Engines. -Eight passenger engines were constructed by sharp, Bros. and Co., Atlas Works, Manchester, in 1846, for East Anglian Railway. Can any of "ours" give me any particulars as to dimensions of these engines (they were all same pattern), I think 5ft 6in. driving-wheel-EAST

ANGLIA.

[45072.]-Percussion Action.-I have a harmonium with four rows of reeds, and I want to attach a percussion action. Can anyone kindly inform me (1) Where are the hammers placed? Are they fixed to the valveboard? Or, do they turn over with the action? (2) Are the hammers fixed to a frame that can be removed like the action of a piano (3) How are the hammers connected to the keys (4) How are they put in and out gear by the stop-APOLLO.

of

[45073.] Guitar Construction. - Could any brother-reader give me any practical advice on the above subject-the best wood, varnish, &c., to use GUITAR.

[45074.]-Pressure of Screw.-I desire to know how to ascertain the pressure of a screw in an ordinary bookbinder's standing press? The screw is 2in. d'am and 2ft. long; the leverage is 4ft., by which the screw s actuated. By this I mean that the pin which is used to turn the screw, is 4ft. long. Information on the subject will be found useful to-G. FRYER, Swansea.

[45075.]-Armstrong's Combination Lathe Major Armstrong's description of his improved combination lathe is not very clear. If he would only give more detailed drawings I should be glad to add it to my lathe. I do not understand the arrangement of the gearing on Fig. 5 and 7. Separate drawings of the castings required with dimensions for a 5ia, centre-lathe would be very acceptable.-W. S.

Since sending us his drawings, Major Armstrong has been suddenly ordered out to India, so it is hardly probable that this query can be replied to for some little time. -ED.]

145095.]-Shoe Finisher's Ink.-Will some of the readers of the "E. M." give a recipe for a good shoefinisher's ink, as most of the inks sold here are almost worthless and oblige-ONE OFTEN IN A FIX.

[45096.) To Practical Watchmakers.-Would some one kindly direct me in the simplest way to fit and adjust balance springs, which are often exceedingly troublesome? I can turn in staffs, cylinders, jewels, &c., with ease. I have seen a fellow who could scarcely turn in a balance staff, a fair hand at springing.-GUYOT.

1450971- Dissolving Gold and Silver. - If "Dunrod" will give full practical instructions in a plain, simple way how this is done, and restored to the metallic, I shall be exceedingly grateful. "With and without alley" means will 9-carat and 22-carat gold dissolve by the same means, and when reduced to metal will they still be 9c. and 22c. respectively, or will they be pure gold, each done separately of course! Kindly describe the I have no back numheating and proportion of acids. bers.-S. GOLD.

[45098.)-Resistance Coils.-I want to make a few resistance coils for educational purposes. Will one of your correspondents kindly tell me the size of German silver wire, suitable for this purpose, and the approximate length of it, which is equal to 1 ohm resistance? 2. The table of tangents for use with tangent galvanometer?length and size of wire best suited for making a galvanometer for small thermopile. 3. Where can I find a

EAST ANGLIAN.

[45099.]- Cochineal Colour.-I am employed in preparing large quantities of cochineal colouring used in the manufacture of a certain description of white paper by the following process:-To 24 gallons of boiling water is added 1lb. of pearlash, then I gently stir in 5 lb. of powdered cochineal and simmer for one hour. After this I add half an ounce of alum, and finish by straining through a flannel bag. Can any of your kind contributors inform me of any process by which I can prepare it, so that it can be kept unchanged for at least a week?-as that I prepare, after about 24 hours, becomes gelatinous, loses some of its colour, and smells very disagreeably.

W. SITTINGBOURNE.

[45100.]-Cube Numbers.-How can I ascertain whether any number is a perfect cube or not? What properties do cube numbers possess that no other numbers possess?-THE VILLAGE PHILOSOPHER.

The City and Guilds Institute.-The programme of technological examinations in connection with the City and Guilds of London Institute for the year 1881-2 has just been issued. It con[45085.] L. N. W. Engines.. Thanks to tains a number of new syllabuses of subjects, such "Diomed" for his promise. Could he, or some other as electric lighting and transmission of power; correspondent, give a list of the Precedent" class of coal-tar distilling and spirit rectification; bread engines, which were built the latter part of last year?-making; the manufacture of linen; linen bleachFORTUNA.j

recom

ing, dyeing, and printing; weaving and pattern 145086.]-Piano Query. To one not in the trade, designing. A new feature in this programme is pianos and cottage pianos appear disproportionate. For arranging the syllabuses of instruction that suband not a competent judge, the prices of short iron giand the grouping together of allied industries, and so instance, an excellent cottage or uplight grand can be purchased for £40, but for an ordinary short iron grand jects which are common to two or more branches one is always charged £80. To me there does not appear of any industry are put under one heading. This to be that extra workmanship in the grand to warrant arrangement further commends itself as offering the 100 per cent. extra cost. Where is the superiority? suggestions for a curriculum of study to be purI should also like to know how it is that several German sued in such technical colleges as those of Bradford, manufacturers (norably Hagspeil, the Coard of the Continent) can sell in the English market a short iron grand Leeds, Huddersfield, &c., which are now being for just half the money that a similar article by any of erected for the development of trade in those disthe eminent English makers would cost. The slight dif-tricts. The lists of works of reference attached ference, if any, in the cost of labour does not entirely to each syllabus are much more complete account for it.-IXION. in this of year's edition the programme, and although many of the works mended are out of the reach of the majority additions to the library of every mechanics' instiof artists and students, they will form valuable tute, and for this reason are wisely included in the programme. There appears to be a considerable increase in the number of registered teachers of the Institute, showing a satisfactory development in this part of its work. The conditions of the registration of teachers become much more stringent after March, 1882. Hitherto, owing to the lack of practical teachers, combining a knowledge of the principles of science and of the practice of trades, the teachers registered under the Science and Art Department have been permitted to hold courses in technology. After March next it appears that those only who have obtained honours at the Institute's examination in the subject to be taught will be registered as teachers.

[45087.]-Proctor's Atlas.-Why has Mr. Proctor, in bis atlas, drawn the precessional circle several degrees with precession knows that it is less than a half-degree di tant from the Fole-star? Everybody who is familiar from it. He may have good reasons fort, but I protest against leaving things in the dark. Light is what we

want.-WYOMA.

[45088.]-Leo Major.-When is this constellation best situated for observing? Is it ever visible before 10 p.m. -CABLISSIMO.

[45089.]-Pulley Dimensions.-A shaft revolves 60 per minute, and has a drum 15in. in diameter. What size pulley will it need to turn another shaft at 180 revolutions? (2) A drum 15in. in diameter makes 60 revolutions per minute. How many revolutions will a pulley Sin. diameter make driven by the 15in. dium?-CAT(45090.)-Telephones. - Would any of our able correspondents kindly describe the induction-coil used in connection with the microphone for transmitting articulation in the best manner? The sizes of the primary and

SOPS.