[41314.]-Stroudley's Regulator for the Westinghouse Brake.-At the request of "A Midland Servant," page 579 of your last volume, I send a tracing of Stroudley's Air-Regulator, as in use upon the London Brighton and South Coast Railway. The regulator is used by the driver for applying, releasing, and graduating the brakes. A circular valve turns with the handle. To apply the brake with full force this handle is moved to the extreme right, closing communication with the main reservoir and at the same time opening the exhaust passage at the back of the valve, through which the air in the main brake-pipe is discharged, causing triple valve pistons to descend, thus applying the brake, as explained in Vol. XXX., p. 191. To release the brake the handle is turned to the left, opening direct communication through the large port-hole between the main reservoir and the main-brake-pipe throughout the train; the compressed air then lifts the triple valve pistons, releases the brake, and re-charges the auxiliary reservoirs. When the pressure in the brake-pipe is fully restored the driver places the handle in the 3rd or "running position." The air from the main reservoir can then only pass through the small valve and passage in. diameter, to reach the main

in the direction of the arrows. D D are the reeds, two to each note, 56 in all. E is a strip of soft leather, having cut in it 28 holes, each in. long by in. wide, one for each note; this makes an air-tight joint between the tune-band and pallet-holes. F is a sound-box, which has f holes cut in it at the top; it is pressed down on the top of the tune-band by springs. G is the reservoir; the bellows are not shown, but are worked by a crank at C. The whole machine measures 20in. long by 12in. wide, and 12in. high, and is very simple and compact. From this description, friend "Saul" will be enabled to say whether he knows it or not; I fancy, however, that it is new, although in looking through the back volumes of "ours" for articles on reeds I came across the description of a similar instrument in principle, under the heading of "Automatic Reed Organ," and the "Melophon' is decidedly a modification of the same thing. I would ask "Saul" if he thinks accordion reeds would do for this instrument? I have never seen any myself, so cannot tell. Having written over 350ft. of music from "Les Huguenots," "Faust," "Tannhauser," and other operas, I should much like to put in better reeds. At present I have in the original ones, but the tone is anything but satisfactory. The execution of the music by the machine is all that could be desired, although, of course, there is no expression.- MELOS.

[41435.]-Medical Coil.-The form of Fuller cell I employed for my small coil, in which a circular porous pot was used, was modified by using a zinc of cruciform section. To show this more clearly, I inclose sketch, showing elevation and plan of zinc element. The original form was a circular zinc of conical shape only, and, for good reasons, could not be as large as the star-shaped zinc. I found

AIR FROM

MAIN
RESERVOIR

MAIN PIPE

THE TRAIN

THROUGH

this an improvement, and always use such in a battery of circular form. As you are doubtless aware, the porous pot also contains a quantity of mercury. This rises readily enough for a given distance; after that it cannot be depended on; therefore the stem connecting the arms with the copper wire was Brunswick-blacked or covered with pitch. The copper wire stem is cast in. When using the plate-form of zinc element, I prefer to protect the upper portion also in the same way. There is one thing I would mention with respect to the Fuller cell, and which, in the hands of amateurs, proves a frequent cause of failure. It is the connection on the carbon. After a short time of use, the fluid is apt to creep up and destroy the connection with the binding screws. When these are cast on in lead, it also aggravates matters. My plan is to soak the top of the carbon in paraffin wax; then drive the paraffin down the plate, say, in., and then electrotype the top. To this you may solder any-shaped binder you like, and the fluid never is able to destroy the connection. The makers for the patentee use a lead cap protected with paraffin; but I greatly prefer a copper connection, as mentioned. -SUNLIGHT.

[41438.]- Midland Railway. - I am much obliged to "Cambridge" for his reply to my query. Will he kindly say whether the distances tion? Will he also give the shortest distance to to Manchester and Liverpool are vid Trent StaLiverpool to the nearest chain, viz., rid Street Stores Junction, Chaddesdon Sidings, Stockport. sake of greater accuracy, this plan should be I should indeed like to have all the distances in miles and chains, and would suggest that, for the adopted where possible, instead of giving miles and quarters of a mile, as is usual in these columns.C. M. W., Leicester.

brake pipe. This small valve is held to its seat by ing to file them down. I may tell "Saul" that a spiral spring (shown in section) of a strength the "Melophon" is of German make, but corresponding to 15lb. per square inch, therefore, 1 cannot find out the maker's name. The the pressure in the brake-pipe is 15lb. less than in reeds are similar to harmonium reeds, but the main reservoir. utilised when releasing the brake, as it enables the by one rivet to the frame, and are altogether very This "extra pressure" is the tongues are much thinner, and only fixed brake-pipe and auxiliary reservoirs to be re-charged rough and cheaply made. The channels are in. and the brakes released very quickly. One of Mr. deep at the bass end, tapering down to in. at the Stroudley's Regulators was fitted to a Midland treble. In putting in the harmonium reeds, I was express engine, No. 802, and used for six months obliged to make the channels gin. deeper before ending September, 1879.-CLEMENT E. STRETTON, the reeds would sound properly, so that the depth [41471.]-Indicator Diagrams. - Take the Saxe-Coburg-street, Leicester, Sept. 23rd. at the base end was in. The accompanying steam-chest cover off, examine the valves to ascersketch shows the arrangement of channels and tan if they get properly on the face of the cylin reeds. AA is the paper tune-band; B and C are der. If you can detect no fault in that respect, take indiarubber-covered gripping rollers, that at C the valves out; examine the faces, also the cylinder being turned by a handle advancing the tune-band | faces. If they are grooved get them planed and

[41424.]-Harmonium Reeds.-Many thanks to our old friend "Saul Rymea," and also to "Musica," for their prompt replies to my query. With regard to the advice given by "Musica,"

surfaced. It is the only way to make a good job. In some cases the fault may be all in the valves. If this is found to be the cause, get the valves planed, and employ a competent practical engineer to surface the cylinder-faces. The defect in the diagram may be caused as follows:-The valve spindle may be sprained or be too light for its work altogether, thereby causing the valves to be thrown off the cylinder-faces at certain points in their travel. Again, a badly-designed valve may cause the defect if the valve is faulty in design. When taken out they will appear to lie on two places, which will be bright. The other part of the valvefaces will show dark-coloured. Place a parallel on the face. If the fault is in the design of the valve, the parallel will touch the dark-coloured part of the valve-face, which shows the expansion of the valve is not proportional. If the parallel lies on the bright places the fault is in the planing and not in the design of the valve. If the fault lies in the design the longer it works the better it will get. A valve of this description should not be planed. It requires easing at intervals till it is properly bedded to the cylinder when it is working; but my advice would be to put new valves in, which would be best

[41503.]—Cleaning old Swords.--Clean with oil and bath-brick, and if very rusty indeed use a file to the worst places. Burnish, and afterwards keep bright with powdered bath brick or whiting. This is the may we do in the army.-FIELD

GUNNER.

in the end. Then take the inside lap off, so that distinct red, similar to the original colour of the
the exhaust port in the valve will cover the steam- paper, is obtained. Then read off the number of
ports 1-16in. on each side, when the valve is mid-divisions of acid used. That number, less 1-10th,
way in its travel. Your diagram indicates 4lb. at is the number of ounces of strong H,So, required to
the termination of the stroke, when the valves are neutralise 1 gallon of gas-liquor. The 1-10th of
made steam-tight. This pressure will be reduced an "ounce" subtracted is due to the slight excess
by taking the inside lap off. Your exhaust opens of acid required to give the distinct red reaction.
earlier, which reduces the pressure at the end of The faint wine-red colour is due to the carbonic
the stroke. Again, on the return stroke, the ex- acid, liberated with effervescence by the sulphuric
haust closes later, which eases the compression or acid from the carbonate of ammonium present in the
back pressure.
You say in the mill the engine liquor. The alkalimeter is graduated to contain 2 fluid
seems to run uneven, but in the engine-room it ounces, i.e., 32 division "ounces," in case the
cannot be detected. The reason it is sooner de- liquor may prove to be more than "16oz." strength.
tected in the mill is through the increase of speed. For more accurate determinations, the gas-liquor
Notice your governor when working. If it is too must be distilled. 1 ounce of gas liquor, together
dilatory in its action, the throttle-valve will dwell with loz. of solution of soda bydrate (of indefinite
too long both in putting steam on and taking steam strength) introduced into A (Fig. 2), through
off. If the weight you are driving is subject to funnel B. Stopcock of funnel shut off and contents
sudden and extensive variation, the governor re- of flask boiled. Steam and ammonia vapours driven
quires to be quick in its action also. If your off into C, which contains 2 ounces 10 per cent.
throttle-valve is in working order and the governor sulphuric acid. The end of the delivery tube must
is properly constructed, you only require to place be cut obliquely, to prevent formation of plugs of
the fulcrum of the governor lever in its proper alkaline liquor in A in the tube, which would be
place.-J. BROADLEY, Bradford.
carried over into C. The acid in C is coloured red,
with solution or tincture of litmus. After boiling
for 20 minutes, the lamp under A is removed, and
C is withdrawn. C now contains 2 fluid ounces of
10 per cent. sulphuric acid, part of which has been
neutralised by the ammonia in 1 fluid ounce of gas-
liquor. By ascertaining the amount of 10 per
cent. acid still unneutralised and subtracting that
[41516.]-Gas-Liquor Test.-There are several amount from 2oz., we find the amount of ammonia
methods by which the ammonia existing in gas-present in one fluid ounce of liquor expressed in
liquor may be estimated volumetrically, but the one terms of ounces of sulphuric acid per gallon of liquor.
now most generally adopted in gasworks is that This we do by running into the contents of C when
called the acid" or "ounce-test." Its object is cool a solution of standard soda hydrate made of
to arrive at a valuation of the ammonia by finding exactly equivalent strength to the 10 per cent. acid.
the number of ounces of sulphuric acid required to When the red colour of the acid and litmus has
neutralise 1 gallon of ammoniacal gas-liquor. Now, turned, not to blue again, but to a reddish purple,
it would be manifestly inconvenient and extrava- the "neutral point has been reached, and
gant to employ such a crude test as this, and hence neutralisation is perfect. We took 1 fluid ounce of
the following modifications are made. We begin gas-liquor, distilled it with soda hydrate for 20
by taking smaller quantities. If we take 1-10th minutes into 2 fluid ounces of 10 per cent. acid.
of a gallon of gas liquor, we must take acid of Into this, when cool, we ran from a burette
1-10th the strength. By so doing we make the (graduated in exactly the same way as the alkali-
respective volumes of liquor and acid more equal, meter. i.e., 2 fluid ounces in 32 divisions), let us
and thus more readily comparable with each other. say, 14 divisions of soda solution (the strength of
1-10th gallon (water) lib. 16 fluid ounces. which exactly corresponds to the 10 per cent. acid)
(The density of gas liquor being so nearly that of before we arrived at the "neutral point," i.e., 14
water-viz., 1,025: 1,000-that the slight error of divs. out of the 32 divs. of the 2 fluid ounces of
taking measured, i.e., water ounces, may be safely acid remained unneutralised by the ammonia in 1
disregarded.) Therefore, if 16 fluid ounces of gas fluid ounce of gas-liquor, i.e., 32-141 = 17) divs.
liquor be fully neutralised by n ounces of 10 per were neutralised, and the liquor was of "17 ounce
cent. sulphuric acid, i.e., 1-10th the strength of strength." The 10 per cent. acid solution is made by
ordinary sulphuric acid, n will be the number of accurately measuring out 54 3 cubic centimetres of
ounces of strong sulphuric acid which would be pure sulphuric acid, of 1812 sp. g., and pouring it
required to neutralise 1 gallon of gas-liquor. But into about 800 cubic cents. of distilled water.
in the laboratory it would be still very inconvenient When the mixture is quite cool, make up total
to use such large volumes as 1 or 2 fluid pounds of volume to 1,000cc. The corresponding soda
liquor, so that the standard quantity of gas liquor solution made by dissolving 100 grammes of stick
to be taken is 1 fluid ounce (corresponding to the caustic soda in 1,000 cc. of distilled water, then by
original fluid pound), which ounce is further di- trial with the standard 10 per cent. acid, again
vided into sixteenths, each sixteenth of an ounce diluting to the necessary strength, so that 2 fluid
corresponding to the original fluid ounce. Thus, ounces of 10 per cent. acid are exactly neutralised
if 1 fluid ounce of gas-liquor required 9-16ths of an by 2 fluid ounces of soda solution. The manufac-
ounce of 10 per cent, sulphuric acid to neutralise it, ture of these solutions requisite for the "acid"
the gallon of gas-liquor would require 9oz. of test is a matter of some little difficulty, and
strong sulphuric acid to neutralise it, and the requires a much fuller explanation than I have
strength of the liquor would be registered as given in the last few lines; but as I have already
"9oz." If only a rough estimation be required, monopolised so much space, I must ask "N. Y. R."
we can use a "Bink's alkalimeter," thus-1 fluid to wait for this part of his answer till next week.
ounce of the gas-liquor is measured out into a H. L. SULMAN.
shallow dish, and one or two strips of red litmus-
paper thrown into it, which will be immediately that the longer the handles and cranks are in
[41534.1-Bicycles Up-Hill.-I have found
coloured blue (solution or tincture of litmus
is no good in this case, as the colour is destroyed proportion to the size of the wheel the easier it is
by the HS, &c., liberated). B is the alkalimeter. to mount hills. The reason seems to be that the
Its capacity is 2 fluid ounces, each ounce being
divided into 16ths, and so numbered that there are
32 divisions, each division representing 1oz. of
strong sulphuric acid, while the gas-liquor in the
basin represents the gallon of liquor. Fill the
alkalimeter (Fig. 1) up to the 1st division with 10
per cent. of acid. Place the thumb over the orifice

=

larger handle helps to steady the machine, and the
longer crank spreads the work.-H. R.

[41536.]-Indicator Diagrams.-In a book
called "The Indicator and Dynamometer," by
Thomas J. Main, M.A. (Professor R.N. Coll.,
Portsmouth), and Thomas Brown, Engineer R.N.
London: Herbert, 88, Cheapside, 1847, a wood-

cut will be found of the indicator diagram, of which I beg to inclose a tracing, and the following passage: This curve presents a singular appear

ance, from the steam and exhaust line intersecting
Since the cushioning begins at the usual place,
that is to say, at the same part of the stroke as
when used as a low-pressure engine, the steam
pent up on the exhaust side, and commencing with
a pressure greater than that of the atmosphere,
soon surpasses that of the boiler, so that when the
port begins to open, the pressure suddenly falls.
Again, when the entering steam is cut off, the
pressure gradually falls, and before the end of the
stroke it is less than that of the eduction; and
when opened again to exhaust, steam enters from
the condenser, and the loop of the right hand
corner is formed." This diagram was taken from
the side lever engine of H.M.S. Bee. Cylinder
20in. diameter, stroke 2ft. The appearance of the
full-power diagrams (p. 47), kindly furnished by
the error in the revolutions (90 instead of 9) enables
High Pressure," together with the correction of
one to speak a little more positively of the defects of
valve-setting and the remedy. Without doubt,
the eccentric-rod is not the correct length, or the
valve is shifted from its proper place upon its
spindle. It is my opinion that if the position of
the valve were corrected and the engine's speed
reduced, keeping the I.H P. constant, good dia-
grams would be obtained without further altera-
tion of the valve. This is what I have said before.
I should not have expected the compression loop
to disappear from the right-hand diagram, Fig. 2,
p. 47, with so low a steam-pressure, and am at present
at a loss to account for it, presuming that no altera-
tion to the valve was made after the diagrams
Fig. 1 were taken and before those of Fig. 2 were
obtained. I should not expect to find inside lap
on the valve; but if, after the alteration of the
position of the valve compression loops still appear,
and it would not be convenient to lower the speed
of the engine, I should remove any inside lap there
might be on the valve, and in case there was none,
give the valve a little negative inside lap. These
full-power diagrams show the engine at 90 revo-
lutions to be too large for the work. If the engine
could be run at a slower speed (the I.H.P. re-
maining constant, in order to obtain fuller dia-
lap might be added
grams without throttling), a little outside
as good diagrams obtained as could be pro-
to the valve, and
duced from an engine without an expansion valve.
The error in the speed of the engine raises the
I.H.P. by Mr. Wood's computation, from the dia-
gram first published to 3 x 10 or 30; and by my
computation to 56 x 10
noticed my request that he would check my calcu-
lations, perhaps with the hope that a still tongue
will make a wise head. At any rate, he has, I have no
doubt, very good reason for remaining silent. From
the diagram first published I certainly should have
thought, with Mr. Mason, that the little vertical line
said to be a part of the loop was not so, and I
cannot think that it is a careful reproduction of the
original. It has no appearance of a rebound, and
it appears as a full line, and not as a broken line in
which the diagram is represented.-ARQUES.

=

56. Mr. Wood has not

[41559.] Non Constant Battery.
"Humble Bee" is far-fetching the name of
Fuller to apply it to such a battery as he describes,
since he does away with what Fuller supplied.
The form described is nothing but a single-fluid
bichromate.-A. H. MECANIQUE.

many holes close together, take one pint of boiled
[41571.]-Zinc Roof Repairs.-If you have
oll, two ounces resin; make the oil hot, and dis-
solve the resin in it.
make hot; powder it up well, and mix with the
Take some whiting, and
resin and oil, to the consistency of thick paint.
With this, paint both sides of a piece of calico,
place it over the holes, and, over it, nail a patch
with copper tacks about of an inch long; if to
boiled oil, and a ball of whiting-better than tar
paint over the zinc, one quart gas-tar, ditto of
or paint.-JACK OF ALL TRADES.

[41573]-Copper Coins.-"Murano's " No. 2 is a Dutch coin of the province of Zealand; the arms should be lion in a rough sea, his hind half submerged, and his head and fore legs raised high above the surface; the leg is the appropriate motto "Luctor et Emrgo." The description of No. 3 is not sufficient to identify it, but it belonged to some of the Italian States: if "Murano" had described the arms I might have been able to tell what it is. I do not know what he means by a "Velvet Crown." Can it be a misprint? There is another

in the query, as "spur" should evidently be spear, "Murano," in giving a legend which is partially effaced. should put for the space of every letter which is wanting; thus, EME**O, the space occupied by the letter which he gives as I, should have shown him that was the stem of a T. The space occupied by a missing, or imperfect letter, is a great help to read partially-effaced inscriptions. I leave "Murano's'

Geological pears

And rabbits and hares,
which irresistibly remind me of the "Widow
Machree," for someone else to "tackle."-
G. J. H.

[41574.]-Varnishing Globes.-Varnish it with white hard varnish. It would be advisable to touch the chafed places up first with a little gum-water, in which a little sugar-candy is put, before revarnishing, to keep the paper from absorbing the varnish.-JACK OF ALL TRADES.

[41575.] Screw and Lever. Neglecting friction (which will render the reply somewhat inaccurate), the resulting pressure will be 100 x 72 x 3.14159 x 4 = 90,478lb., more than 40 tons.— R. C. BISWAS.

[41575.]-Screw and Lever.-The_simplest rule for calculating this is as follows:-The force exerted by the screw is to the power as the distance traversed by the point of application of the power is to the distance it causes the weight to move. In the case you give, power 100lb., pitch of screw in., length of lever 3ft., it is evident that when the end of the lever moves round a circle whose radius is 3ft., i.e., whose circumference is 18-85ft. nearly, the weight will be moved in. Thus, as in. is to 18-85ft., so is 100lb. to the pressure exerted by the screw, or roughly, about

40 tons.-PLONI ALMONI.

[41580.]-Blacking for Boiler Top.-Rub it over with a mixture of boiled oil and lampblack. From the latter the grease should be taken before mixing by placing it in a flower-pot, the top and bottom sealed with clay and subjected to a good heat.-JACK OF ALL TRADES.

four equal parts Ab, bc, ed, dE; EC (equal to
one of those parts) joined to AE; AC represents
the diameter of circle circumscribing the rectangle

and EF

=

32

=

B

ABCD, or the base of triangles ABC, ADC,
whose perpendiculars BE, D, are alike; and,
consequently, AC x BE gives the required area
of rectangle. 2nd. Arithmetically-A E being 32,
4; 52 4 gives 8 EC; and 32+
40 for A C, and as EF EC:: EC: EB, or
D of triangle ABC, ADC whose base AC is
4:88: 16, so 16 is the perpendicular EB or
40. Or 40 x 16 gives 640 the area required.
3rd. By Double Slide Rule-

8=

=

4 on slide N set opposite 8 on line A, and
B
1 on 39
set opposite 8 on slide N,
C
N is 16 on line A E B or bD;
is Ans. 640 on A as before;

opp. 8 on
and
40 on

B
C

=

[41602.]-Distilled Water.-The process of distillation deprives water as found in wells, streams, &c., of all its solid contents, such as iron, lime, &c., which are left behind in the still. Distilled water is thus chemically pure. It is flat to the taste, but perfectly healthy. The long-continued drinking of hard water containing much lime is injurious; but in districts, the soil of which is free from lime, it is beneficial to add lime to drinking water on account of the teeth and bones. -W. H. BOOTH.

[41602.]-Distilled Water.-When we speak of distilled water containing nothing but H2O, we mean that it is a pure compound of two parts by weight of hydrogen and 16 of oxygen. If such water be separated into its component elements, it will be found that the hydrogen occupies twice as much bulk as the oxygen. Distillation, if properly performed, does deprive the water of iron, as well as air. It is the absence of the latter that makes distilled water taste flat and unpleasant.PLONI ALMONI.

[41608.]-Piano Smallwork.-Cut strips of cloth just wide enough to meet when pulled through; see it does not curl up in pulling through; touch of glue or paste on cloth, cut off flush with sharp knife (or razor's brother). Wire or damper arms; but rails (or socket) should not must work free in either rails for damper wires be so free as damper-arm bushing. Bushing butts is a nice job. Cloth is sold on purpose for this. Cut strips as before; then cut one end of cloth to a slanting point, put a little glue on cloth, twist round with your hand a few times, and through the small holes; paste or glue-only a little you will have a nice firm point to start cloth more than show the cloth the glue. An amateur may reclothe damper arms or rails; but the butts want some artful moves performed on them to make them work their important part. Be prepared, after getting the cloth in and cutting off flush, for pushing it out again in getting centre wire in. Passing a wire through, a shade smaller than centre wire, after bushing, will help you; and if you are

[41581.]-Deal Sawing.-I never heard of a machine capable of cutting, with a circular-saw, 9in. and 11ín. deals into boards, to be worked by hand or horse. The power required to perform such work is considerable, and. if "A Subscriber " has not room enough to work either a gas or steamengine, I fear he must be content to buy his wood ready sawn to the required thickness, or send his deals to the nearest saw-mills.-TIMBER MER--W. H. BOOTH.

CHANT.

[41582.]-Oil-Proof Cement.-Fine plaster of Paris, mixed with gum-arabic. Water is both impervious to either oil or spirits. I have used it with advantage in many things, paraffin-lamps more especially.-JACK OF ALL TRADES.

[41587.]-Triangle.-Since in the given figure the triangles AEB, BEC, and FEC are similar, that is, they have all their angles equal, their sides are in proportion; so AE: BE: BE: EC, and AE: BE::EC: EF; and therefore-(1) AE, EC = BE (2) A E, EF BE. EC, and the area of the figure is equal to A C, E B. AE, EF

From (2) EC=

(1) BE3

(2) BE

[41609.]-Piano Springs.-"G. L."will find a mode of making hopper springs and wire used, in Vol. XXX., 772, p. 439 (39126). The sort of spring "G. L." describes is so old that it is new to me, but I think you must mean the ordinary spring fixed in tenoned part of hopper and working in fly of same.-W. H. NYE.

reply to this query, the sentence printed: "I should [41610.]-Telegraph Line.-Referring to my think your Leclanché cells would be sufficient,' should read: I should think four Leclanché cells would be sufficient.-W. B.

requires too long an answer to insert. If you will [41610.]-Telegraph Line. — Your question advertise your address I will supply every infor mation. You would not need a covered wire, and you would most certainly have to get permission to cross houses. Other wire, if not too near, will not hurt.-A. H. MECANIQUE.

[41593.]-Gas Governor.-Oh, you insatiables, who are for ever wanting advertisements thrashed out in these columns? I have nothing gratis. Has not the gas governor question been new to tell you; you will find a detailed description of how to make one if you will but consult the index issued with the number in which your query appears, under the head of "Gas-saving appliances." If you want to buy one, open wide your purse and go to the best makers (you will find more [41611.]-Pyramidal Nitre Crystals.-Nitre than one in Westminster), and you can be suited. substitute this value in See in any case that your inside pipes are of good (potassic nitrate), under all ordinary circumstances, size, not less than in. at the very least, where they dihedral summits. Those needle-like crystals obcrystallises in anhydrous 6-sided prisms, with A E', EF; also from have to supply all your burners-better if in-tained by "S. W. C.," have this form, and so also and put about 7 or 8-10ths pressure on your governor.-PLONI ALMONI.

(1) EC3 AE, EF; the area will therefore be:-(AE + VAE. EF) (3/AE. EF) for the values given, A E 32, EF = 4. (32 + 8) (16) 640 square chains. = 64 acres. -PEAKE. [41587.]-Triangle. The following solution may, perhaps, serve purpose of "H. H." Refering to figure accompanying query, for brevity,

let B Ex

ECy.

ABC being a right-angled triangle, B E is a mean proportionate to A E and EC (Euclid, Book I.). Similarly, EC is a mean proportional to B E and

EF.

[41594.]-Heating Water.-432 of a cubic foot of water converted into steam at 212°, and mixed with 7 cubic feet of water at 60° (assuming 60° as the ordinary temperature), will produce 7.432 cubic feet of water at 100°. Similarly 1:05 cubic feet of water as steam will raise 7ft. of water at 60°, to a temperature of 150°, producing 8.05ft. as a result.-W. H. BOOTH.

[41594.]-Heating Water. Supposing the "ordinary temperature" of the cold water to be 50° Fah., the quantity of water to be converted into steam would be about 24 gallons in the first of the cases stated, and 4 in the second; for 7 c. ft. 43.7 gallons

[41587.)-Triangle. Three methods of finding the area required may be described as follow, thus: 1st. Geometrically-E F being 4; AE divided into-H. R.

A

will his so-called pyramidal crystals; they only differ in size and development (nitre can, however, be obtained in small rhombohedra by allowing a drop of solution to evaporate spontaneously). "S. W. C." has failed in getting large crystals, either by using a shallow crystallising pan (one in which the liquor can cool tolerably quickly) and agitating the crystallising liquor, or he has used a too-concentrated solution. Large nitre crystals must be allowed to form gradually, and, therefore, the mother liquor must be cooled slowly. This is generally effected in saltpetre works by using large and deep tanks (about 10ft. by 10ft. by 6ft.), the large body of liquor contained by them taking two or three days to thoroughly cool. saturated solution is avoided; best strength of mother liquor for large crystals is about 80° Twaddle Hyd. (= 1,400 sp. g.) at 100° C. Pieces of plain deal wood are placed horizontally in the tank, at different heights, in order to give attachment for growth of crystals. Care must be taken forms on the surface of the liquour, and all agitanot to break the crystalline film which at once tion must be avoided. Large nitre crystals always contain a considerable amount of the mother liquor inclosed in their numerous crevices, and hence they are not so pure as the smaller crystals obtained by agitating à concentrated hot solution of saltpetre in a shallow vessel. These latter are thus obtained so fine as to be termed "saltpetre flour." They may, with a little careful washing, be obtained with only 3 parts of chlorine per 1,000,000 of the salt (chlorine being the chief and most injurious impurity), while the large crystals can rarely be got to contain less than I pt. Cl per

5,000. They are obtained purest by recrystallisa- and pay him off at once, and employ another if
tion of the saltpetre flour in the manner previously necessary. Don't by any means allow it to be
described.-H. L. SULMAN.
thrown into Chancery, as the lawyers will then
get the best part of it. Send another query stating
intrusted, and probably "Sperans" will advise
to whom the administration of the estate was
you.-Os.

[41612.]— Ornamental Turning. - "J. L.," lished on this subject. I have a good one called in reply to this query, says there are no books pub"On Lathes and Turning," (Northcott), published by Longmans, Green and Co., London, 1876, which describes various lathes, chucks, and tools, and how to use them, and contains several examples of fancy turning. -JOHN S. B. Bell, C.E., Newcastle.

[41614.]-Analysis.-I should advise you to get Jones' junior course of "Practical Chemistry," where you will find all you require for qualitative analysis. Price 28. 6d., published by Macmillan.

-PLONI ALMONI.

it contained any oil or greasy matter it would not
dry properly. Try benzole, not benzoline.-Os.
[41658.]-Clock Problem.-It is scarcely pos-
sible for the hands of a clock to be so placed, but
be. The minute-hand travels 12 times as fast as the

it is easy to see where the next coincidence would
hour-hand, therefore when the minute-hand has
made a complete revolution or returned to I., the
hour-hand will have traversed five minutes, and
will also be at I. So at I. the hands must coincide.
If "Ego Alpha" meant to say the hour-hand at I.
and the minute one at XII., which is a sensible
position for the hands to be in, I can give him an
coincidence by 60, and divide by 11. In the present
arithmetical rule. Multiply the hour preceding the
= 511 That is the number of
minutes past the preceding hour-i.e,, past one
o'clock.-R. C. BISWAS.

case

=

1 × 60 60
11
11

[41631.]-Medical Electricity.-To "SIGMA." -As to this question, I can only say that cures of some diseases are undoubtedly effected by aid of electricity, but that very little is really known about them; that much of what is said and claimed to be effected is illusory, and that in many instances, the active agent is the patient's own nervous power, "though cures are effected under electrical treatinent, guided by what is miscalled imagination, one of the most potent agents in medical treatment of all kinds. Certainly, I have known cures effected, and under my own hands, among others one of paralysis of the eye, or perhaps, more correctly, eyelid. I have also used it in strains, lumbago, and neuralgia [41661.]-Spirits. This word, when applied to with advantage. direction of current from a coil is to lead copper It is merely a popular term, and was used in the The simplest mode of testing sion, and it has no place in chemical nomenclature. any chemical preparation, is not a scientific expreswires from it into a solution of sulphate of copper; after a time one wire will show a coating of new early days of chemistry (for want of a better). It deposited copper; that terminal corresponds to the was generally applied to anything which was exwire from the zinc or negative pole of a battery.-tracted or distilled from anything else, as being the SIGMA. essence or spirit of the latter.-Os.

[41614.]-Analysis.-J. Heywood will find the following a good way of distinction between the three acids in a mixture of KI, KBr, and KC1:(1) Add to the solution containing the mixture a solution of cupric sulphate and sulphurous acid; a dirty white precipitate of Cul (cuprous iodide), insoluble in water, but soluble in ammonic hydrate, indicates hydriodic acid. (2) Add sufficient sodic hydrate to precipitate the iron and copper compounds present; filter, evaporate the filtrate to dryness; divide the residue into two parts (a and b). (a) Add potassic chromate and sulphuric acid; a brownish-red gas is evolved (CrCl), which condenses to a red liquid, decomposed by water into chromic acid (which gives a yellow precipitate with a lead salt) and hydrochloric acid.

[41632.]-Induction Coils.-Length of spark is only one element, the thickness or body of spark is another; the first is due to tension, and depends on length of wire; the second is due to quantity, Both are, and depends on thickness of wire.

[41664.]-Haust or Worm in the Throat of Calves.-In Suffolk this parasitic disease is called "the husk." The husk affects the throat and airpassages of young animals, and this year has prevailed chiefly amongst calves. The filaria, threadlike worms, belong to the order Nematoda, and

This indicates the presence of hydrochloric acid. of course, affected by other elements in the con- they quickly pass from the throat to the bronchi

(6) Add a little chlorine water, and shake up with
ether. A red solution indicates hydrobromic acid.
J. Heywood will also find Geo. Valentin's "Quali-
tative Analysis" a good text-book. It is pub-
lished by J. and A. Churchill.-GEORGE-E. R.
[41617.]-Chemical Tests.-You will find the
required tests, as well as those for about 150 other
organic substances, in the ENGLISH MECHANIC for
1878 in paper then appearing on Organic Chemistry.

-HUGH CLEMENTS.

[41620.]-The Heart, and the Truss for Hernia.-Perhaps "Interested" will feel more so if he is told that about one-fourth of the adult population of this country are more or less ruptured, and that they wear various kinds of appliances for the relief and cure of this complaint, and that if they are properly applied there is not much risk of any injury to the action of the heart.-H. BARNABY.

[41623.]-Fruit Salt.-The composition of these articles, under various names, is very similar; they generally contain tartaric acid, and either potass or soda. I am sorry that "F. W." has taken considerable quantities of this stuff. I can assure him that my 30 years' experience in these substances leads me to assert that no medicine has yet been discovered which is "generally beneficial to health." H. BARNABY.

[41624.]-Liver Complaint.-Although "L." has given only a very short account of his troubles, and a great deal more is necessary, I am disposed to predict that, when his case is investigated by one who understands it, the result will prove that he is suffering from want of exercise and from foul air. Should he obtain the formula which he asks for, I hope he will not swallow any of the medicines, but that he will set about examining his surroundings, so that. in future, he will breathe pure night and day; that every night he will feel the fatigue of some outdoor exercise; in this way he must work out his own salvation."-H.

BARNABY.

Liver Complaint.

[41632.] - Indicator Coils.-Comparison by length of spark is almost the only mode you can employ. One coil may be wound with, perhaps, 50 per cent. more secondary than another, but, from faulty construction, it might not give a larger spark than one with a far less length. Hence, if the length of the secondary be known, it is not safe to calculate the length of spark on that basis. If you were to favour me with a more definite query: not doubt I might be able to help you, but at present I do not see my way clear to say more.

-SUNLIGHT.

had better spend a few pounds in making an ex-
[41635.-Lavender and Peppermint.-You
cursion to Mitcham, where these herbs are grown
in profusion, and make it your business to get all
the information you can when there.-Os.

[41642.]-Air-Pump.-I really do not see why
the piston of an air-pump should not travel as
fast as that of a locomotive running 60 miles an
hour; but you will require a steam-engine to drive
it. I don't think you will get the ball-valves suffi-
ciently accurate.-Os.

[41642.]-Air-pump. An air-pump piston driven at a great speed, such as you name, would, in my opinion, quickly destroy the valves, and so fail altogether. In fast-running marine engines the speed of the air-pump is considerable, but as it never is as great as that of the pistons, I do not think we have any data to go by giving the result when a speed of even a fast-travelling marine piston has been reached. I have had a good deal to do at one time with condensing-engines, and am of opinion that it would be impracticable to use anything like the speed you name, except the stroke be pretty long; and here another difficulty would come in. But, in any case, the valves would quickly suffer from the rapidity of the beats, and, no matter what form was used, they would fail. Indiarubber on metal gratings would work best. Metal valves would simply destroy themselves in a few hours.-SUNLIGHT.

[41624.]
-Seeing that
"Liver" is dissatisfied with the progress he made
under his first-rate medical man, it is a wonder he
does not try some of the pills and other quack
remedies. They are warranted to cure, if only
[41643.]-Snails.-I would suggest a steam-
you take enough of them. "Liver" lets us into jacketed pan perforated at the bottom. This would
the secret that his "stomach and liver were out of it on another pair into which the oil (if there is
order" when he went to the doctor; but he does any) will drop. Any tinsmith will make a double
not explain how he came to put them out of order. pan, so that the steam circulates completely round.
However, being as capable of seeing as far through-Os.
a milestone as most people, I would suggest that [41645.]-Bending Glass.-I cannot give the
he might find Dr. Abernethy's advice excellent, exact details of the furnace. I think in glass
Live on sixpence a day-and earn it." I would works it is called an annealing oven. It is done
add, earn it by "digging," or by carrying seaweed on iron moulds, to which the glass, when red-hot,
from the shore to the farm. By the way, that's an adapts itself.-Os.
excellent prescription for the victim of dyspepsia;

and you get it, stamp and all, for 2d. !-SAUL

RYMEA.

[41628.]-Fruit Salt.-2oz. car. soda, 2oz. tar. acid, 2oz. cr. tartar, 2oz. Ep. salts, 2oz. sifted sugar. Dry the salts in the oven, and beat fine; then mix the whole well together, and keep in a dry place. The above forms a useful family aperient, and has been used for years by-TYNE SIDE.

[41630.]-Legal Proof of Birth.-"Stella" should state to whom "letters of administration" were granted, as if they were granted to the widow and family they have the matter in their own hands, and should get the solicitor's costs taxed,

and the proper remedy is to have self-acting
[41646.]-Gas.-The case is a very common one,
regulators on each floor to control the pressure.
But the difficulty may be avoided by using pipes of
ample size for the supply, with taps on the pipes
leading to each floor, and opening these only just
enough to permit the proper quantity to pass. Gas,
being only half the weight of air, rises in the pipes
and seeks outlet where the air-pressure is least,
that is, at the highest points, and if the supply is
deficient, it will, of course, fail at the lower points.
-SIGMA.

[41650.]-Indiarubber Solution.-Probably
your coal-tar naphtha was not perfectly pure. If

and lungs, and there become encysted, and soon kill

the animal. To dislodge them from the throat it is necessary to set up a violent fit of coughing. This is done by shutting the affected animal up in a room with a small pan of burning sulphur. The fumes are inhaled and the cough set up by them serves to dislodge the worms. This method is I am informed, very effective, although not unattended with danger, as if not closely watched the fumes will produce suffocation.-JABEZ HOGG.

heat. You will have to raise the temperature in [41666.]-Heat.-Certainly it will require more either case to 32° before the ice liquefies; but in the case of ice at a temperature of 0°, additional units of heat would be requisite to compensate for the difference of temperature.-SUNLIGHT.

block of ice at 0° F. will require a certain amount [41666.] Heat. Yes, most decidedly. The of heat to raise it to the temperature of 25° F., and

then it will also require the same amount of heat to reduce it to water at 32° F.. as the other block at 25° F. Perhaps "G. T. J." is getting confused about "quantity" and "intensity" of heat.-R. C. BISWAS.

but in

[41667.] Photo-Lens in Lantern. The difficulty which "C. P. C." names is one that must occur when using a suitable lens. The size of picture and distance from the screen entirely depend on the focal length or power of the focus-lens. Hen, to get over this trouble, many makers use a combination as short as 3in. focus; this gives a large picture at a short range, many instances sacrifices definition to size. Hence there are two evils to be avoided. But to deal with our friend's case: the lens he names, which is doubtless a half-plate or cabinet one, is useless to him, as far as the lenses go. His remedy is plain, and it is this:-Either let him get a quarter-plate portraitlens of 33in. or 4in. focus, and use it instead of the half-plate one he now employs; or he may adopt another plan, and such would be to obtain a single achromatic lens, made to fit in the back cell of his present rack and pinion mount, the front combination being removed altogether. If he gets

an achromatic of 4in. back focus, he will be able to obtain a disc of something like 9ft. 6in., the lantern being 12ft. from the screen only; whilst if the lantern were 25ft. distant the picture would be nearly 20ft. diameter. The shorter-focus lens (4.5in.) would give a brighter picture, as the combination would be better situated in the cone of rays. If the querist decides to adopt either of the courses open to him, as I have mentioned, should he so desire, by advertising his address, I might, very possibly, be able to assist him in the matter of the lenses.-SUNLIGHT.

[41670.] Finishing Electro Plate.-There polishing electro-plate," simply because there is has been no information given on "burnishing and none to give. The goods are burnished not polished, and they are done by a class of people (generally women) who have made it their special business, and who work at a tolerably cheap rate. There are plenty of them in Clerkenwell, and the best plan would be to get a few lessons from one of them, as I do not expect many of them read the ENGLISH MECHANIC.-Os.

[41673.]-Iodised Sarsaparilla.-Add iodide of potassium to decoction, or liquid extract of sarsaparilla, an expensive and, in my opinion, useless preparation. Two or three grains of iodide will be