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tants of this empire to assume the charaeter of an industrious and an enlightened people; and the effect of which has laid the foundation and completed the bulwarks of that virtuous magnanimity which has made the world to wonder at our works, and her most populous empires to tremble at our strength. The satisfaction resulting from the knowledge that we live amidst so much toleration, is truly sufficient to fill every British bosom with the most patriotic feelings-to establish concord and tranquillity to cause us to blush at the insignificance of provincial prejudice, or religious intolerance-and to unite all parties under the ties of paternal affection, and fraternal love.

To the indulgence of the Committee of Managers of this work, and the influence of that individual whose favour we

have already so often felt, and whose generous feeling has at present so largely manifested itself, it is that we are indebted for the formation and enlargement of our Institution. To him, then, whose assistance is so important and examplary, whose sole motive is our instruction and improvement, and whose desire always is our interest, it becomes us gratefully and unanimously to render what assistance lyes in our power for the support and improvement of the establishment.

We, my friends, have witnessed its origin, and are in part sensible of its utility, but future experience and general improvement alone, can show the extent of that utility. May the success of this establishment exceed the wishes of its worthy founder, and the gratification thence arising be more than the delicacy of words can express!

LETTERS, QUERIES, AND ANSWERS.

ON MAKING GINGER BEER.

GENTLEMEN,-In No. LVI. Page 430, Vol. II. of your Magazine, Z. A. inquires the best mode of making Ginger Beer. I know not whether the following plan be the best or not, but I think it a pretty good one. Take 1 oz. of ginger, well bruised, 1 oz. cream of tartar, and 1 lb. white sugar: put these ingredients into an earthen vessel and pour upon them a gallon of boiling water; when cold, add a table spoonful of yeast, and let the whole stand till the next morning. Then skim it, bottle it up, and keep it three days in a cold place, when it is fit for use. Good firm corks must be used, and they must be secured with twine or wire. DICK, in Nelson-Street, who makes the best Ginger Beer I have ever drank, uses lemons instead of cream of tartar. I am not aware if it is to this the superiority of his beer is owing, but it is considerably more expensive than cream of tartar. I am, yours, &c.

A. Z.

ON REMOVING ECHOES IN

CHURCHES.

GENTLEMEN,-In No. LIX. Page 16, Vol. III. of your Magazine, one of your Correspondents in Cupar inquires the best plan for getting rid of an echo in a church with which he is connected; and as I perceive no one has as yet said

any thing on the subject, I beg leave to make a few observations.

It is well known that echoes are produced in every room by the reflection of the sound from the walls; and, consequently, the smoother and more unbroken the walls and roof are, the more will the echo be increased and reflected. In a large room it is often extremely difficult to prevent a very disagreeable echo. The best mode, however, of getting rid of what in a church must always be considered a nuisance, is by breaking the wall, or rendering its surface uneven by mouldings or other ornaments. A hole in the roof might have the effect your Correspondent wishes. Wool and sawdust are both very bad conductors of sound; and carpeting, or moreen, or other woollen hangings or furniture, may be used beneficially. If the echo proceeds from a hollow partition or ceiling, it may be much diminished, and often altogether destroyed, by filling up the hollow with saw-dust. I shall be glad if these observations are of any use to your Correspondent, if you think them worthy a place in your excellent miscellany.-I am, yours, &c.

J. M. L.

EXPENSE OF OBTAINING A PATENT.

GENTLEMEN, A Correspondent, in No. LXIV. Page 96, Vol. III. inquires

· 160

THE GLASGOW MECHANICS' MAGAZINE.

the expense connected with obtaining a patent. It is not very easy to answer this question precisely, as the expense varies very materially under different circumstances. The ordinary expense is about £100 for each of the three kingdoms; so that before a patent can be obtained for Great Britain and Ireland, the expense is never less than £300. In many cases, however, it amounts to three times that sum. I am, yours, &c.

A RESPONDENT.

QUERY.

GENTLEMEN,-If any of your able and numerous Correspondents could devise a plan by which an old waste may be drained out of a large unbroken extent of old workings, to the rise of my present workings, without endangering the lives of the men employed in pricking the waste, and at the same time allowing the present workings to be kept going, by allowing the waste to be run

USEFUL

To fix the Colours of Drawings in Chalk or Crayons.-In order to fix the colours of drawings in chalk or crayons, and keep them from rubbing off, it is recommended to pass the drawing through a vessel containing sweet or skimmed milk, when the desired effect will be produced.

A Paste or Powder for Razor Strops.Take equal parts of sulphate of iron, (green copperas of commerce,) and common salt; rub them well together, and heat the mixture to redness in a crucible. When the vapours have ceased to rise, let the mass cool, and wash it, to remove the salt, and when diffused in water, collect the brilliant micaceous scales, which first subside; these, when spread

off, as the pumping engine can deliver it at the pit mouth, they will confer a great obligation not only upon me, but upon the whole coal trade. By the common mode, the workmen are in continual apprehension of being surrounded with water in the bowels of the earth, and often lives are lost, numbers of men are thrown out of employment for a considerable time, and great loss is sustained by the coal masters. Any practicable and safe plan, therefore, of obviating these dangers and losses, would be a favour to a numerous class of beings who labour for their daily bread in those regions of darkness and danger.

A COAL HEWER.

Waste is the technical name given to old workings full of water.

Rise-workings is the technical name given to those parts that are above the level of the other workings.

Pricking is the technical name given when the miner with his pick makes an opening into the waste.

RECEIPTS.

upon leather, soften the edge of a razor, and cause it to cut smooth.

For cleaning Marble, Jasper, Siena, and Porphyry-Mix up a quantity of very strong soap lees with quick lime, to the consistence of milk, and lay it on the marble you wish to clean, where it may remain 24 or 30 hours; it is afterwards to be cleaned with soap and water, and it will appear as if new.

To make Furniture Oil.-Put some alkenet root into a glazed pipkin, with as much linseed oil as will cover it; let it boil moderately, it will become of a strong red colour; let it cool, and it is then fit for use.

NOTICES TO CORRESPONDENTS.

B. D. GA Workman-A. B. Dollar have been received.

Erratum in last Number; Page 188, line 3, for "19," read "9."-Errata in a few copies of this Number, page 146, col. 1, line 25, for "figure 1," read " figure 7."-Col. 2, line 23, for "Fig. 4," read "Fig. 7."-Page 147, col. 2, for" Fig. 2," read" Fig. 3."

Communications from intelligent Mechanies will be very acceptable, in whatever style they may be written, if they contain a full account of the invention or improvement, which is the subject of their notice.

Published every Saturday, by W. R. M'PHUN, 155, Trongate, Glasgow, to whom Communications (post paid) must be addressed.

CUBLL, PRINTER.

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ON AIR VESSELS.

Air vessels on lying Mains. In applying air vessels to a lying main, for the purpose of aiding a steam engine in raising water, and of keeping up a continued stream, we have often observed an error which not only renders them, we may say, entirely useless, but detrimental, causing them to add to the weight of the engine they are intended to lighten and relieve. It is often desirable, and would be more convenient, if it could be done with propriety, to have the air vessel outside the engine-house; but by doing this, it must, of necessity, be placed at a distance from the pump, in the immediate vicinity of which it ought to be. A very slight consideration of the subject will show at once how injurious this must be. Let us suppose the pump, A, (see fig. 1 of the plate,) which is worked by a steam engine, to be employed in lifting water, forced through B, the lying main. In order that a constant stream of water may be kept up in the main, it is necessary to use an air vessel; and in place of applying it at D, close to the pump, in order not to incumber the engine-house, or for some such reason, it is removed outside the house, to a distance of 20, 30, or 100 feet, say to C. Experience, however, has shown that in such a situation the air vessel does not perform the office for which it was intended, but causes it to be injurious to the working of the engine. For if we suppose the engine to be at work, and the pump lifting water, the main will, of course, be full of water. Now, it is obvious that the air vessel can have no beneficial influence on the water lying in the main, between it and the pump; so that every time the working box is raised, the body of water contained in this portion of the lying main re

quires to be put in motion, which must increase the burden of the engine. But this is not the only injury which the removal of the air vessel to a distance from the pump creates, for when the air is condensed in the vessel, and the water, by the lifting of the working box, rises in it to a, on the return of the box the air will begin to expand in the vessel towards b, expelling the water. The current thus created should flow through the main to the place of delivery, this being the intention of the vessel, and this would be the case, had it been placed at D; but from its distance at C, part of the expelled water will flow towards B, giving a retrograde motion to the water lying in that part of the main, which will thus meet the new current produced by the relifting of the box. We all know

what immense force a column of water has when thus suddenly impeded in its progress, and how great a shock the engine and the main must sustain by the concussion.

We recollect of many instances of the defect of which we have been speaking, in which the concussion created by the opposing currents was excessive, and often burst the main and rent it in pieces. The whole, however, was cured by removing the air vessel to the immediate vicinity of the pump.

Air vessels on lying suction pipes.

Although not immediately connected with this, we beg to suggest to our readers that in all pumps, whether wrought by an engine or by the hand, where there is any length of lying suction pipe, as at E, it is extremely useful to have an air vessel on it, say at F, as it is a great ease to the burthen of the engine, or other power employed in lifting.

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MECHANICS' MAGAZINE.

In the common hand pumps, where there was a portion of lying suction pipe, we have known, after the application of an air vessel, one

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man do more work, and with greater ease to himself, than two could have done without it.

APPARATUS FOR MEASURING THE FORCE OF STEAM.

A MOST Convenient apparatus for
trying experiments upon steam on
a small scale, is shown in section,
fig. 2.
It consists of a strong
hollow copper or brass ball, a,
about 4 inches in diameter, sup-
ported by a stand which admits a
spirit or other powerful lamp to be
placed under it for heating the
water. On the upper part of the
ball are four orifices; in the central
one, b, an upright glass barometer
tube of 30 or 40 inches long, and
with an open top and bottom, is
fixed by an air-tight screw cap,
while the lower end of the tube
dips into a small open-topped re-
servoir within the ball, containing
just quicksilver enough to fill the
tube. A mercurial thermometer is
fixed by a similar cap, c, to the
second orifice. The third, d, has
a conical safely valve opening out-
wards, but which may be held
down in a greater or less degree
by an adjustable spring; and the
fourth, e, is furnished with a stop-
cock for the purpose of exhausting
the ball of its air, or permitting the
sudden escape of its steam, or con-
veying it away by a pipe for any
experimental purpose: f, f, is a
scale graduated to inches and tenths
for observing the rise of the mer-
cury. With such an apparatus, the
beat of water, and its corresponding
strength of steam, can be very
accurately measured, for the ther-
mometer measures the one, while
the steam pressing on the surface
of the quicksilver, and forcing it up
the glass tube, indicates the other
by the height to which it ascends,

as measured upon the scale ff; and by experimental researches made in this way, by M. Bettancourt, and afterwards rendered more correct by Mr. Dalton, and by others, it has been determined that the force of the confined steam of water, corresponding with different degrees of temperature, is very nearly as expressed in the Table which we gave in our last.

In making experiments upon steam, it is always best to judge of the state of its expansion by a mercurial guage, though the same thing can be done by valves properly loaded. In the instrument shown at fig. 2, the steam generated in the hollow ball, a, will press on the surface of the quicksilver in the small reservoir, and press it up the tube, f, f. But since steam at 212 degrees is balanced by atmospheric pressure, and the tube, f, f, is open at its top, the quicksilver cannot begin to rise until that temperature is increased; and as atmospheric pressure is very nearly equal to 15 lbs. on the square inch, and is balanced by about 30 inches of quicksilver in the barometer tube, it follows that each 2 inches of rise of the quicksilver in a tube like f, f, must be equal to 1 lb. of pressure or elastic force in the steam; and, consequently, a mercurial guage, when consulted in conjunction with a barometer, becomes a most accurate, and is a very sensible test for the strength of steam; and such a guage generally is, and ought always to be, applied to the boilers of all steam engines, On

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