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applicable to all horses feet, and which would prevent

although the frog was not

And as the nails of the

the contraction of the heels, in contact with the ground. shoes are frequently broken, loosened, or altogether lost, and the shoe thereby prematurely removed from the horse, and the horse in consequence often amed, and always rendered unfit for use until again shod; and as the inconveniences from the loss of a shoe are at all times great, but particularly so in horses used for the cavalry and for hunting, it appeared a great improvement to apply a shoe which would be more firmly united to the hoof than any other shoe hitherto employed, and therefore productive of the best effects in all feet thất require much iron and small nails. This shoe can be applied with proper effect by the most ignorant smith, as the simple difference from all other shoes consists merely in the inner and posterior part of both heels of the shoe being turned up so as to touch the inner and posterior part of both bars, by which means the heels of the hoof cannot contract, or the shoe have the smallest degree of lateral motion. The length of the turu up of the shoe is not very material, but it should be sufficiently long to embrace the heel of the bar, and yet not to touch the bottom of the cavity between the bar and frog. A bar-shoe may also be applied with a similar projection, to press against the heels of the bars. If the hoof is already contracted, the heels may be mechanically expanded a little by a pair of farrier's tongs every time the horse is shod, and the shoe applied so as to press with more force against the bars; but under these circumstances the hoof should first be made moist by standing two or three hours in water, and the horse not used for a day or two afterwards. In witness whereof, &c. VOL. XIII.-SECOND SERIES. Rr Descrip

Description of a Mortar for preparing Mercurial Ointment.

By Mr. JAMES PHOENIX, of Liverpool.

Communicated in a Letter to the Editors.

GENTLEMEN,

SEVERAL processes for making Unguentum Hydragyri having been proposed, but which are in general too complicated, the annexed sketch exhibits a mortar for that purpose, which unites simplicity with dispatch.

Fig. 6 (Plate XII.) is a front view of the mortar complete. A is a half section of the mortar; shewing how it should be cut, with a cavity at the bottom for holding the mercury, which by the friction is worked out and in till perfectly oxyded. B B is the pestle, with a wheel (C) in the middle, and two cross bars of iron loaded with lead at the extremities DD, to increase the rapidity of the movement. E, the cramp for fastening the whole together. FF, two uprights to support the handle G in working. G the handle, with an endless screw to turn the wheel C.

I am, Gentlemen, yours, &c.

JAMES PHOENIX.

Improvements on Wheel Carriages.

By Mr. P. ANDREWS.

Communicated in a Letter to the Editors.'

With Engravings.

Fig. 7 (Plate XII.) is a ground plan of a waggon, or other four-wheeled carriage. 1 is a pole; 22 are two splinter-bars; 3 3 are two chains attached to the extremities of both axle-trees by means of hooks or eyes,

whose

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-whose shanks or stems pierce the axle-trees, and are screwed tight by nuts at pleasure; 4 4 are the axle-trees; 5, 6, 7, 8, are the wheels. The two axle-trees revolve on centre bolts in the same manner that the fore axle-tree does in all four wheeled carriages; the chains 3 3 are fixed -diagonally from 5 to 7 and 6 to 8, and take off all the strain or force from the centre-bolts. The chains are so placed, that the one is the whole width of the axle-trees above the other, therefore do not touch each other, and the parts of the chains are always comparatively at rest -amongst themselves, consequently take off all friction. -As the chains take off all strain or force from the axletrees, those parts may be made much slighter, and the whole fabric of the waggon much lighter. The wheels may be made of any height, either to pass under the waggon or to lock into a nook in the side. They should be cylindrical; and the fore axle-tree, if those wheels pass under, should be shorter than the hind axle-tree by the breadth of the fellies; or if the fore wheels lock into the side then that axle-tree should be so much wider; by this method the wheels would have different tracts, and be of great service to the roads, as they would cover twice their own breadth on the fellies, and operate as rollers. From the position and effect of the chains the centre of gravity, of motion, and of draught, is in the same point, consequently (if the wheels are of the same height which they should be) the line of draught will be horizontal, and in every possible position a straight line; therefore such a carriage cannot be overturned unless it should be drawn on any bank, &c. whose elevation shall exceed forty-five degrees, and will run much lighter, and with less force, than any other carriage.

Rr 2

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