P.S. You were so good as to notice a pamphlet of mine, in which I recommended the trial of an instrument for increasing the relative powers of the sun's and moon's attractions; and as I am now convinced that what I proposed is physically impossible, I shall be equally obliged if you, will make this known to the public.

NEW MODE OF HEATING APARTMENTS.

SIR, Two well known qualities of air, are those of compression under mechanical powers, and expansion when exposed to the influence of heat; by this latter process its specific gravity becomes affected, that is, in equal bulks of hot air; and air at the common atmospherical temperature, the former was found to be the lightest. It is upon a knowledge of this property in air, to be affected by heat, that the warming of rooms is conducted, and it is only in those cases where this principle is not properly attended to, that apartments remain in a manner unbenefitted by the fires they possess? thus, it may happen that the setting of a grate too far back in the fire-place, proves detrimental to the warmth of the room, by carrying the greatest portion of heated air up the chimney flue. Under all circumstances however, the fire in the common grates, gives out a very partial heat to the room, and a very unnecessary quantity of warm air escapes along with the smoke.

The common fire-grate being in numerous instances preferable to stoves, it has been my study to render it still more serviceable in the heating of rooms, upon a plan cheaper than any before employed, and at the same time simple and not in the least interfering with the "setting up" of the grate, which alone, easy as it may appear, is yet matter of sufficient difficulty with many workmen. I have not only aimed at economy, but portability also, and I flatter myself, this warming apparatus, will be found in practice to be a useful and convenient addition to household furniture, from its being applicable to the grate of any fire-place, and possessing equal effect in all situations. In families this cheap and simple apparatus will be found peculiarly beneficial in the airing of chambers, damp rooms, cellars, &c., where, as ornament is not a matter of much consideration, those intended for such purposes only, may be made of the cheapest materials; but for the parlour or drawing-room, as a matter of course, a little more expense must be incurred to produce it in an elegant form.

When in use, it will be observed that this air heater, though comparatively small (for two might be hung on a bar eighteen inches long) has the power of distributing very hot air, which is attributable to the following cause; air, like all other imperfect conductors of caloric, only receives an impression of heat at the point of contact, that is, the heat does not spread itself rapidly through the whole body of air, but only by slow degrees, therefore I have divided the body of air, presented by this machine to the action of heat, into

strata, (if I may so express myself), of these there are three, (see the engraving) and the hottest alone is allowed to pass off into the apartment. The division from which this escapement takes place, is supplied with air from the remaining two, prepared with a degree of heat, derived from the waste heat of the metal, so that the whole apparatus has been contrived on true philosophical principles.

Having said thus much in its favour, it may be deemed superfluous to launch out into further details of its merits; under this impression I shall proceed to give some account of its construction.

H. D.

London, June 18, 1829.

Reference to the Engraving.

Fig. 1. A perspective view of the apparatus, the references to which apply also to the other figures. a, is one of the hooks for attaching it to the upper bar of a grate; b, a projection or hood, to convey the hot air into the apartment; c, an aperture for the admission of cool air; d, d, a curved slip of sheet iron, to prevent thre smoke from being drawn into the room by the hood b, which it completely effects, even in a fire-place otherwise liable to smoke; e, a metal strap to receive the tongue g, Fig. 4. of the plateff, for lengthening the hood b, and carrying the hot air further into the

room.

Fig. 2. A section of the apparatus, showing the serpentine passage of the air in the divisions h h h; f, the situation for the plate Fig. 4, marked by dotted lines.

Fig. 3. A back view of the air-heater, a a a, three hooks, behind which is inserted the curved plate d. The middle hook should project about one inch, and the outside ones, about two inches, to suit a circular or a straight barred grate, as, for the former all the hooks will be engaged, but for the latter, only that in the middle will be serviceable.

Fig. 4. A plate, to be used when the draught of the fire-place affects the course of the current of hot air. It has merely its two outer edges turned square.

Fig. 5. The heater dissected; the dotted squares show where the trays ii, are to be hard soldered or rivetted, ccccc c, three oblong openings for the admisssion of air, through which it takes the winding passage shown by the small darts.

The whole apparatus (except the curved plate d d) is best made of sheet copper or brass, and all the seams may be rivetted, provided they be afterwards luted with a little thick white or red lead paints. It may be also proper to notice here, that though the projection or hood is supposed to extend only one foot or one foot and a half from the fire-grate, it may with ease, be contrived of greater length to bring the hot air still further into a room.

H. D.

4

INSTANTANEOUS LIGHT APPARATUS.

TO THE EDITOR.

Guernsey, July 22, 1829.

SIR,-Although I am aware that it is a common chemical experiment to effect combustion, by the sudden compression of atmospheric air, I do not remember to have seen or heard of tinderboxes in England constructed on this principle, notwithstanding they have now become common in this island, and in many parts of the continent. I have one of this kind in my own use, of French manufacture, which I find to be so very convenient, and so much superior to other instruments made for the purpose, that I am desirous to see a description of it in your Journal, in order that my friends in England may avail themselves of its utility. Annexed is a sketch of this little apparatus (see Fig. 14, Plate II), which requires no explanation to the scientific, but to those who are otherwise, I would state, that a represents a neatly-turned brass cylinder about 3 inches long accurately bored throughout; the upper part of this tube is of a bulbous form as at 6, and at the bottom is a leather washer, which is pressed air-tight against it by means of a screw turned in the head of the tinder-box c; d is a plunger which fits the tube airtight, and having a cavity at its lowest extremity, in which is placed a small piece of the amadou, or German tinder, (taken out of the magazine c.) Thus cleared the plunger is placed into the tube, then thrust down smartly, and immediately withdrawn, by which process the tinder is ignited.

I remain, your constant reader,

AN OLD FISHERMAN,

The apparatus described by our correspondent is by no means rare in this country, but, as it is deserving of being better known, we give it insertion.-ED.

NEW CARRIAGE FOR PALMER'S RAILWAY.

By Mr. T. CHAPMAN, Royal Row, Lambeth.

MR. PALMER'S railway is a single rail, elevated sufficiently above the ground to allow of two boxes being suspended, one on each side of the rail and near to it, from two wheels one behind the other on the rail, and, when making a turn, a portion of the rail turns with the carriage on it.*

Mr. Chapman's contrivance is to make the carriage move from one angle on to another, or along a curved rail as well as a straight one.

Fig. 1 is an end view; fig. 2 a side view, partly in section. à a, the rail; bb, two wheels on the rail; these carry the turning-plates *This Patent Railway is fully described, with Engravings, in the first volume of this work, first series. No. 7.

VOL. IV. No. 73.

E

1ST AUGUST, 1829.

cc, each having four friction-rollers; dd, the carriage plates lying on the friction-rollers; ee, upper plates; ff, the vertical axis of the wheel frames or turn-plates cc; they pass through the plates d and e, from which the boxes g g are suspended by the lateral arms hh and ii. Now, as the wheels and frames b c can turn freely on their axis ff, they each require four guiding rollers jjjj, to keep them in a right line with the rail, and to cause them to turn as the rail turns. These carriages should not be farther asunder than is absolutely necessary for the required curve of the rail, it being a great advantage in Mr. Palmer's carriage that the boxes are so close to the rail, and so little top-heavy, that a considerable inequality of weight produces very little disturbance of the equilibrium. The bottom of the carriage has a joint at one-third of its length. and is held up at this by the hooks k k; by removing these, the contents may be let out: the fixed portion of bottom is made sloping, so that it may be readily emptied.

IMPROVED LITHOTOMY FORCEPS.

Communicated by MR. CLULEY, of Sheffield.

AMONG the diseases incidental to mankind, none are more distressing in their nature than the stone in the bladder; the extraction of which, under the most favourable circumstances, is attended with considerable risk, and much bodily suffering: the latter is frequently increased, by circumstances which can only be discovered during the operation. Such, for instauce, as the size, shape, or number of the stones, as well as their consistency in texture; therefore the result of the operation depends on contingencies, and on the facility with which the stone can be extracted.

As a manufacturer of surgeons' instruments I have had many opportunities of witnessing the operation of lithotomy, and am convinced that the forceps in common use are not calculated to extract the stone with ease or expedition, the blades of which being only slightly concave within, and furnished with teeth, render them extremely objectionable; for the thickness of the blades, added to the diameter of the stone, especially a large one, causes such an extension of the forceps, that much laceration takes place, and often compels the operator to again apply the knife to enlarge the orifice, the stone often eludes the grasp of the forceps, in consequence of which, when the operator considers he has the stone fairly within the blades, he too frequently applies additional pressure, in order to keep hold during the extraction; in this the operator is frequently defeated by the stone breaking in pieces under the severe pressure, or small portions breaking off by the action of the teeth of the forceps, which may form a nucleus of a second fornration of stone.

The improved instrument has three blades (as shewn by figure 5), and is well adapted to extract large and irregular formed stones, also such as may be in a decomposed state; for, when the stone is within the improved forceps, no extra pressure is needful to retain it there, and the blades being hollow and of a bulbous form they receive the stone within their cavity without any extra extension, or probability of breaking the stone, or any part thereof during the

extraction.

PURIFICATION OF LINSEED OIL.

MR. Cugan's process, though resembling M. Thénard's in the first part of it, is completed by the judicious introduction of steam; by means of which the oil appears to be almost entirely freed from acid, and the black feculent dregs subside in the course of twelve hours, leeaving the upper portion of the oil quite clear, and greatly improved in colour, and in those qualities for which it is valued by the painter,

The quantity of oil that he operates upon at once is about 100 gallons. For this, three quarts, that is about ten pounds, of sulphu