LIST OF FIRE-ESCAPES, Submitted to the Society for Pre venting Loss of Life by Fire, and exhibited on the 19th February, 1829.

(Continued from p. 68.)

The

8. A rope or chain, in length twice the height of the upper window from the ground, attached at one end to the slings of a strong canvas bag between three and four feet deep, and about eighteen inches in diameter, with a hoop at the top, and circular board of the diameter of the bag fitted inside to the bottom. other appendages are, a bolt through the brickwork, just above the window, having a block or pulley at the outer end, that may be reached by putting down the upper sash; and a balcony to be attached to the window, with a kind of trap door of a circular shape, through which the bag or fire-escape will pass. Should fire take possession of the lower part of the house, the rope may, in a few minutes, be passed through the block, and the end sent down to persons outside, who would keep the bag suspended half through the hole in the balcony, from which even children could step in without any danger, and be lowered to the ground. A line or chain, leading to the ground from the bottom of the bag, is intended to guide it clear of the flames below, if required. The rope to be coiled in the bag, which, when flattened down, may be stowed away in the room, in a very small compass. Invented by Lieut. Cook, 127, Long Acre.

9. A machine (on four wheels, intended to be drawn by a horse), consisting of sliding ladders and cradles, to be worked by winders. This machine would enable a fireman to stand on the ladder and deliver the water, in a sloping direction, on the fire. Invented by Mr. John Davis, and approved by the Society of Arts.

10. Sliding ladders and cradle,

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on a four-wheeled carriage. Invented by Mr. Hudson, and fully described by him, in a communica tion to the " Mech. Mag." vol. ix, p. 434; see also same vol. p. 310.

11. A machine on four wheels, consisting of a sexagon folding ladder, to be raised by a winder, and regulated by means of a second winder, so as to clear obstacles in its ascent against a wall. On the upper part of the ladder, two pieces of iron, in the form of hooks, are affixed, for the purpose of producing firmness, by obtaining a hold on the parapet of a house. Invented by Mr. Oliffe. Allowed to be very in. genious, but too complicated for the purpose of a fire-escape.

12. Apparatus for saving lives and property, consisting of an iron cub or box, with chains, &c. Invented by Mr. James.

13. A set of poles fitting into sockets, and to be used on the principle of a lever, and to turn in any direction, by means of a swivel. Invented by Mr. Cohen, and much approved of for its simplicity.

14. A machine invented by Mr. Joseph, by means of which a person may be raised to any part of a building without the least personal risk. He may carry with him the spout of an engine, and apply water to any particular spot, and rescue the inmates, by sending them down in one scuttle, while the other ascends to his assistance and safety. The machine is equal to forty-eight feet in height, and may be fixed in very few minutes.

15. Buston's fire-escape, exhibited by Mr. Wix, Stockwell.

For an account of this escape, see letter on the preceding page, from Mr. Baddeley; also "Mech. Mag.," vol. ix. pp. 213, 310.

16. Key's apparatus for protecting houses in narrow streets, &c., in the event of a fire.

(To be continued in our next, when we shall give Mr. Baddeley's account of Mr. D. Davies' double rope escape.)

WREST-PINS OF PIANOFORTES.

Sir, Your correspondent A. M. C. p. 150, ol. viii., inquires what kind of

wood is best calculated to receive the wrest-pins of a pianoforte. I should rather think, that if among others he can distinguish one that is of closer texture, and, at the same time, as easily penetrated by the screw, it might be preferred; and I think there are woods better adapted to the purpose than oak. But is the following hint of any use? Suppose we remove the wrest-pins from their present situation, and place a strong wire or cylindrical bar firmly in their ' places; coil the wire once (or oftener if required) round this wire or bar, continuing it to the wrest-pin (placed a convenient distance back), to receive and stretch it in the usual way. By this means, will:not the friction of the wire on the intervening cylinder greatly reduce its action (when in a state of vibration) on the wrestpins, so that they may remain firm in their places, and the instrument be prevented from going out of time by their giving way when it is played on? I am no musician, and this method may, perhaps, be already in use; if not, it may be worth trying, as its application is very simple.

PLAN FOR WORKING THE PUMPS OF A VESSEL DURING A STORM.

Sir, Observing that your valuable publication is open to every thing that is novel or interesting, I beg to lay before your readers a plan for working the pumps of a vessel when it has sprung a leak during a gale, and the sailors are fatigued and exhausted. It as often occurs that a vessel springs a leak when going with velocity before the wind, as in any other situation. Now, I believe, that it has been contrived in some steamers that the paddles should be moveable at pleasure. Now, supposing that paddles upon this construction were applied to a vessel say an East Indiaman (but without the steam-engine and machinery),—it appears to me that the

motion of the vessel through the water would cause the paddles to revolve, and so turning the crank would work the pumps, and thus save the labour abovementioned. In order to work more pumps than one, it would only require a series of cranks and connecting rods to join them. Should the above meet with your approbation the insertion of it will much oblige

Your most obedient servant,
J. N. H. C.

Canterbury.

SOLVENT FOR PUTTY.

Sir,-In your 6th vol. p. 44, "A Constant Supporter" inquires for a solvent for putty; and in p. 77 of the same volume," J. L." suggests (not asserts) that it may be effected by nitric or muriatic acid spread over it with a small brush. He also says that vinegar will effect the same purpose, though it requires a much longer period. In p. 171 of the same volume, "W. C. of Winchester," writes that be bad dissolved putty by means of muriatic acid, as suggested by "J. L. ;" and bere the matter has rested ever since. Your readers, I dare say, concluded, that the thing sought was found,at least I did so, and was satisfied that I now knew how to remove glass from an old sash without destroying it. But no such thing. A few days ago, I endeavoured to remove some squares from an old frame, and had recourse to the abovesaid solvent. When applied to the putty, the muriatic acid produced, for a moment, a rapid effervescence on the surface, and that was all: it remained as hard and incorrigible as ever. Nor did repeated and long continued applications mend the matter a whit, or soften the putty, in the smallest degree. I now learn, moreover, that several other persons have tried the experiment with the self-same result; so that there does not appear to have been any thing peculiar in my putty, or my acid. Will" W. C." account for this? and if there was any thing unexplained in his manipulation, will he point it

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(which are of equal length), at d and e, the frame F F F F hangs, with the gimbol f and its upright bar G. To the middle of the lowest part of this frame is hung the large glass ball or bulb of a barometer H; the tube of which, I, goes down into the quicksilver in the glass cistern K. This cistern is supported by two rods L L, whose ends hang from the contrary ends of the cradles A a and Bb; the right hand rod from the end a of the cradle A a, and the left-hand rod from the end B of the cradle B b. A very small degree of attention to this connexion will show, that if the bulb H be pulled down it must draw up the cistern K, and if the cistern be pulled down it will draw up the bulb; for, as either end of a cradle goes down, the other end must rise. The cistern being open at top, the atmosphere exerts a varying pressure on the surface of the quicksilver; and when heavy, forces the greater part of it up the tube I into the bulb H: this makes the bulb heavy and the cistern light; the bulb, therefore, descends, and draws up the cistern. On the contrary, when the air becomes light, its pressure is so much the less on the surface of the quicksilver in the cistern; and being then unable to support the lengthened column of quicksilver in the bulb, part of it descends into the cistern, which, becoming thus heavier than the bulb, descends and draws it up. And thus, when the air is heavy the bulb descends, and ascends when the air is light, through more than double the space that the mercury rises and falls in a common barometer. The frame F F F F and its upright G being connected with the bulb, rise and fall with it. To this upright bar G is attached the windup frame M,-which is shown on a larger scale in fig. 2. In this frame are two thin metal plates m and n, toothed like the blades of saws, one set of teeth m pointing downwards, and the other set n pointing upwards. When the frame falls, the teeth of the saw m, by means of a sliding movement, engage the teeth of the wheel N, and turn it round in the direction shown by the

arrow; when the frame rises, the saw m is disengaged by the sliding movement, and the saw n is brought into connexion with the wheel N, which it turns round in the same direction as before; so that whether the frame ascends or descends, it is continually turning the wheel N in the same direction. This frame moves between four friction wheels, which retain it in an upright position. O is a catch which falls into the teeth of the wheel, to keep it from being turned in the contrary direction, by any accident, during the short interval of time between one of the saws leaving the wheel and the other taking into it. On the back of the wheel N is a pulley, with sharp-pointed pins fixed in the bottom of its groove, for laying hold of the endless chain 1, 2. Above this is just such another pulley, over which the chain also goes, 3, 4. This last pulley is fixed on the axis of the great wheel (R, fig. 1) of the clock movement, by which the whole of the clock-work is put in motion.

Returning to fig. 1;-the endless chain just described passes over the four upper pulleys U U U U, which are fixed, and under the two lower ones S and s, which rise and fall with the heavy weight T, on one side, and the lighter counterpoise 1, on the other side, which hang from the pulley frames. The weights

consisted of two boxes made of thin brass plate; but T was filled with lead, while t was quite empty. The weight T acts with half its force of gravity upon the part 5, 6, of the endless chain, and with the other half upon the part 7, 8. By pulling the former part, it turns round the great wheel R as fast as the motion of the balance of the clock will permit that wheel to move. It will be seen that if this motion continued for a short time, the weight T would go down to the bottom, and then the clock would stop. But the train of the movement is such, that the weight would keep the clock going a whole year, before it would descend quite to the bottom of the machine. By the abovementioned contrivance of the wind-up frame M, which, as it moves up and down,