NO. 120 EFFECT OF DEPTH ON

THE QUALITY OF WATER. SIR,-Can any of your Correspondents inform me, through the medium of your Magazine, whether water is softer at one hundred yards deep than it is at eight or ten yards deep? I understand this is the case at Leeds; and that, for the use of steam-engines, they shut the top water off, and bore from eighty to one hundred yards, in preference to going to the river. I wish to know whether this applies generally, or only to particular situations, as Leeds, for instance,

Also, What is best, for steamboilers, to soften water?

NO. 121. COMPARATIVE STRENGTH

OF MALT AND SUGAR.

SIR,--Will you allow me, through the medium of your pages, to make an inquiry relative to a subject which interests every man who brews his own beer-I mean the comparative strength of Malt and Sugar. The basis of all fermented liquors being saccharine matter, I conclude that, when the prices of these articles are such as to render sugar the more advantageous, as regards the quantity of spirit to be obtained for the same sum, there is no disadvantage in using it largely as a partial

ANSWER TO INQUIRY.

No. 97. QUESTIONS ON GUNNERY.

[Second Answer.]

SIR,The only certain way of computing the charge of powder for a fowling-piece is by weight, and not by the space it occupies in the barrel; and also the quality of the barrel should be expressed, for a difference in expansion makes a difference in the quantity required for a charge: for instance, the Damascus and common barrels, on account of their less expansibility than the twisted barrels, shoot equally strong with the latter when the charge of powder is reduced four grains; for it must be obvious to every one, that the shot could not be dislodged with equal force when the sides of the barrel yield to the sudden expansion of the exploded powder; and here I may add, that the shot travels with a much greater velocity than the rarefaction that moved it, which shows that the shot receives no accumulation of force by the quantity of powder which is put into the barrel, more than what is fired in the first instant, as the shot is propelled by the first rush of the air on the combustion of the powder.

The accompanying scale' will be found as correct as the latitude of the question will allow. I have formed it for my own use, and I may add without exaggerating, that it is the result of trials made on several hundred guns.

To the second question I can give no answer.

98

HENRY OGLE,

Schoolmaster, at Rennington, near Alnwick, Northumberland.

Description.

ABCD represent a plain piece of board, with a place in the middle, pp, for the slide, A, to move up and down in. Qis a quadrant made fast upon scale B. By enlarging this quadrant to a semicircle, QQ, the scales B and C, turning upon a centre, will set to solve all questions in oblique as well as plane trigonometry. B will turn off from scale A to any distance, as at L, the pricked line; and by sliding A upwards or downwards in the board, the scales will set to the given dimensions of any triangle whatever, and give both the plane and the true contents of all parts at the same time. By raising scale B to the pricked line, M, by a plummet hung at the centre, it becomes a good level; it will also give all the dimensions of a square. If you set slide A to the dimensions of one side of a square, set slide C to the same dimensions in the bottom scale, and C becomes the diagonal of the square. I have solved all the problems of practical navigation by this in

strument, and a great number of promiscuous questions, with great ease and ac

DOUGHTY'S RUBY-POINTED PEN. SIR,-I shall be obliged by any of your Correspondents favouring me with the address of the manufacturer of this article. I purchased one last year, and have found it answer very well; but having had an accident with it, and thinking I could suggest a trifling improvement by a personal communication with the maker, I applied for his address at the shop where I bought it, but was told by one of the partners that it was not regular to give it to me. I could not but think this rather contemptible, as I have seen these pens in fifty shops in London, and that they are therefore not made exclusively for that in question; I therefore take this method of avoiding a se

cond time the irregularity of endeavouring to obtain that information which I mind would feel disposed to deny me. foolishly thought no person of libera. I am, Sir, respectfully yours,

BRICKS.

G. H.

SIR,-Several answers have been soliin No. 75, concerning Bricks. Will you cited by your Correspondent Rusticus, allow me to add to his inquiry a request for information on the nature of Pipe Clay. Is it a fit substance to make bricks of, where it can be obtained in great quantity ?

Is there any essential difference between the clay used for brick, and that only a finer sort of which the latter vesfor pottery or crockery-ware, or is it sels are made?

Perhaps you will best reply to both of us, by pointing out some treatise on brickmaking, if such there be.*

In the absence of scientific intelligence, 1 can inform Rusticus, that the red colour in tiles and bricks is not always caused by ferruginous matter; but those burning white will, where they touch others in the kiln, become red, and this red is breaking them: those bricks which are only on the surface, as may be seen by red all through are probably of ferrugiuous clays. Frost, before bricks are dried, is their greatest enemy; for even on burning them afterwards, they become absolutely rotten, and will not stand the least blow.

The Dutch very generally do over their brick buildings with a mortar or plaster mixed with oil and colour; blue, red, or light pink, and grey, are the most common colours: when dry, such walls have a kind of gloss like varnish, and, of course, resist all wet.

In the United States of North America, brick houses are painted afterwards; they are not otherwise deemed finished. Red lead and Spanish brown are used.

Many of the brick houses in Englaud admit the wet through the walls, from the light, bad, porous quality of the brick; especially when a shower of rain, mixed with snow, comes with a strong wind. I have known an eighteen-inch wall so penetrated quite through. The Dutch method of using coloured mortar, as above described, is certainly a better mode of proceeding than the English custom of using bad absorbing bricks,

* As good an article on Brickmaking as we remember to have met, is to be found in the Encyclopædia Metrópolitana, whence it was extracted into our own pages (vol. 11. p. 76-79). It is from the pen of Mr. Elmes, architect.

and not admitting them to be made weather-proof, for fear of losing their colour. The coating or covering can be of any colour desired.

Pug-mills are so numerous about London, I advise Rusticus to examine them for himself, which will answer his purpose better than any description I could give. Clay alone will certainly make bricks, but not all kinds of clay, though nearly all..

I remain, Sir,

Your most obedient servant,

TILLBROOK.

LOADING RIFLES.

SIR,-It is the present practice among gun-makers to provide their

Rifle Gun-cases with a small wooden

mallet, which is used in charging the rifle, to force the ball into the mouth of the piece, by several blows, as the ball, with the linen or leather (which is placed under it), is frequently too large to be conveyed into the barrel by any other method. Now, as it must necessarily be acknowledged by any person who has the least knowledge of gunnery, that the direction of the ball is materially as sisted by the perfectness of its sphericity, and as the upper part is flattened by the above custom of using the mallet, it appears that this method of forcing the ball into the barrel is, to say the least of it, illjudged. I was led to these remarks, about a week ago, by happening to see some gentlemen trying rifles at Chalk Farin; one of them, who certainly was a good shot, went several times rather wide of the mark, although assisted with a rest. Those present imagined there was some defect in the position of the sights. I observed, however, in my own mind (as suggestions are not always taken as well as intended), that, in charging, the ball was very much flattened by the use of the mallet, and I judged that the gentleman would never make a certain shot while this was the case.

At last I observed the ball go into the barrel more easily, and without being flattened at all; now, thought I to myself, if he covers his object, he has a fair opportunity he firedthe ball, as I expected, shivered the

card, which fully confirmed my opinion of the impropriety of using the mallet in the above manner. Now, as it is necessary to have some effective method to force the ball into the barrel (as the tight fitting of it is a sine qua non to a good marksman), I should think that a short punch or ramrod, with a concavity at one end corresponding to the size of the ball, covered over with leather (such as are seen on some rifle ramrods), might be applied to the ball, while the other extremity might be struck with the mallet. This method (if the punch be kept tight against the the ball. When it has entered a few ball) will never injure the form of inches into the barrel, the regular ramrod, with a similar concavity,

lifted up and down to strike the ball, must be used, but it never should be which should be sent home by pressure, or it will never carry fair. I am, Sir,

(for the first time) Your humble servant; T. M. M

N.

EXTINGUISHING FIRE ON BOARD SHIPS.

SIR,-From the many accidents of ships taking fire at sea, and these commencing in parts of the vessels not easily got at, it appears to me that a reservoir, on deck, with pipes either of leather or lead, communicating and opening into various store rooms, such as the spirit-room, powder-room, &c. would be the means of procuring an instantaneous application of water. The mouths of the different pipes should be marked, so that only that which led to the part on fire should be opened. In my opinion this arrangement would give passengers and all on board a very great assurance of safety; and I have no doubt the expense of it would be compensated by the allowance the Insurance Offices would make in favour of such ships.

I am, Sir,