The pistons, brought down, as before described, by weights, are again raised by means of vertical levers, their fulcrums about one third from their centres; the shorter ends of the bows are connected by rods to excentric wheels; and the plungers, which have displaced the bricks from the moulds, are again forced up by springs. The vertical levers of the pistons are supported by an axle resting upon two standards in the middle of the frame; and the parts are placed so as to produce a double engine discharging the bricks at both ends.

The machine or engine above described, is contrived to make eight bricks at every revolution of the main axle; a greater or less number, however, may be made by a machine of this construction by slight alterations and modifications of the parts. In order to make tiles by these means, it will be necessary to vary the proportions or sizes of the various parts of the moulds according to the size and figures of the tiles to be made.

The patentee, lastly, observes: "I do not mean or intend hereby to claim as my invention, any of the individual parts of which this machine may be composed, but I do hereby claim the improved combination thereof; and particularly the apparatus for feeding and forcing the clay or brick earth into the moulds, either in its natural state, as taken out of the earth, or after being mixed with the usual materials for making bricks and tiles."

Inrolled, May, 1821.

See Hague's patent for pottery ware, bricks and tiles, Vol. II. page 21-also Shaw's patent for making bricks by machinery, Vol. II. page 23.

To SAMUEL BAGSHAW, of Newcastle under Lyne, Staffordshire, for an Invention of a Method of Forming, and Manufacturing Vases, Urns, Basins, and other ornamental articles, which have been heretofore usually made of stone, or marble, from a combination of materials never heretofore made use of in the manufacture of such articles.

THE method of forming these urns, vases, or other articles in imitation of stone, consists in preparing a shape or nucleus of clay of the desired form, and baking or burning it afterwards in the usual manner of pottery articles; or it may be made of cast or wrought iron, or indeed of any other hard material. This shape or nucleus is then to be coated or incrusted both within and without, with a cement of the plastic nature, capable of being modeled in the same manner as other plaster figures. In this mode, a variety of ornamental articles may be wrought, so nearly resembling stone as not to be easily distinguished from it.

The cement recommended to be employed is that called "Parker's Roman Cement," which may be used either alone or mixed with colours and other ingredients, so as to resemble any particular kinds of stone, at the desire of the manufacturer.

The form of the nucleus or a portion of it, is to be prepared in a rude manner in common clay, by an apparatus, known among potters by the name of the throwing wheel, where the clay intended to form the article is turned round quickly, and moulded both within and without to the desired form by the hands of the workman. The mode of finishing an urn or vase, when made of clay, as described in the specification, is by providing a table, and placing on it an iron plate or tablet,

mounted upon a spindle, so as to be capable of turning round horizontally: the spindle is to be carried perpendicularly, and its pivot secured in a bearer above. The nucleus, rudely formed, is to be baked as usual; after which it is placed upon the middle of the revolving plate or tablet above described, with the spindle passing through its axis, in which situation it must be firmly secured.

A board, cut in profile to the form of a section of the vase, is then brought against it, and fixed perpendicularly to one of the upright standards of the frame, between which board and the nucleus a sufficient space must be left to admit of a thick coating of the cement. The tablet or plate, with the vase fixed upon the spindle, is then turned round, while the cement is applied by hand to the vase, and the superfluous cement becomes scraped off, leaving the nucleus coated in the form of the moulding cut in the scraping board: the form of the vase is then completed; it may be removed from the plate by withdrawing the spindle which passed through it while turning.

When the article is of large dimensions, the nucleus may be formed and coated in several parts, and afterwards united together by cement. This apparatus is employed only for the production of such articles as are circular; but eliptical figures may be wrought by similar means, provided that the revolving plate or tablet be constructed as an oval chuck or excentric lathe.

Inrolled, September, 1821.

Original Communications.

To the Editor of the London Journal of Arts, &c.

OUR researches on vegetation are by no means exhausted; on the contrary I am rather disposed to consi

der them as just begun, notwithstanding the assiduity of a Hunter and a Knight, and other physiological enquirers.

The question as to the degree of heat found in living vegetables has not been examined with that accuracy which could be desired. That a certain degree of heat above the freezing point does exist in most vegetable productions analogy and observation have in some sort demonstrated, but we want more decisive experiments to determine accurately the fact.

I have been led into these remarks in consequence of having read, in a late Medical Journal, some observations controverting the theories of Hunter and Brodie on this subject. The following experiment is adduced as a proof that the heat found in the centre of a tree is not the effect of vitality.

"On the 3rd of January, 1821," says the experimenter (whose name from delicacy I omit) " I pierced a hole in a young poplar tree obliquely downwards, from three to four inches in depth, just big enough to admit the bulb of a thermometer, and into which such an instrument was placed. I then drove a nail into the tree, to which I suspended another thermometer. I examined them in about an hour afterwards, and found them both standing at 31° or one degree below the freezing point.

Now, Sir, I really think there never was made, in all the annals of philosophy, a more bungling experiment than this; or, at least, one which is more bunglingly described. In the first place, the temperature of the external air, independently of the tree, is not stated ; a circumstance of very great moment: for the connexion of one of the thermometers with the tree by a nail might, and very probably did, influence the temperature of that instrument; and, besides, may not most living vegetables be surrounded, in calm weather, with an atmosphere, which, at a certain distance, may influence the thermometer? And, instead of stating the degree of heat indi

cated by the thermometer a few minutes only after it was placed in the hole in the tree, we are told its degree of heat after it had been there an hour, when not only communication with the external air must have been going on for that period, but when, perhaps, evaporation also from the hole might have taken place so as to prevent any accuracy whatever on such a nice point. The species of the poplar is not mentioned; this in experiments on vegetation is absolutely necessary, as we have, I think, no reason whatever to conclude that all trees of the same genus, (may not, even of the same species), possess equal degrees of temperature.

Such experiments, it must be admitted, require great delicacy; and, therefore, that above detailed is, in my humble judgment, of no force whatever; and from which no practical deductions ought to be made.

Trusting that some of our experimental physiologists will turn their attention to this subject, and determine by accurate data the degree of heat actually existing in living vegetables,*

Northampton Square,
Dec. 17, 1821.

I remain, yours, &c.
INQUISITOR.

* We recommend this subject to the attention of a chemical lecturer in Dorset Street; a gentleman whom we ourselves are not in the habit of hearing, but who, we are told, often honours the Journal of Arts by his especial notice in his lectures, though in such a way that we by no means feel disposed to say ago tibi gratias. To this experimental friend we would give a word of advice, which we hope, if it does not make him silent, will induce him to be, at least, civil, and, once for all, be an answer to his illiberal insinuations, because we would not publish in our Journal a letter of his which would have disgraced a quack doctor's hand bill: ne sutor ultra crepidam! We trust, for his own sake, that he will be quiet; we should be sorry to have occasion again to mention the subject, or to become the lictor.—ED.