"4. Being of a uniform colour throughout its whole substance, it is peculiarly applicable to articles subject to wear and friction.

"5. The Mosaic Gold, when applied to interior decorations and furniture, does not produce the unpleasant odour of bronze or brass.

"6. In case of accident, its original colour and lustre can be easily recovered by the ordinary modes of cleaning gold or silver.

"7. In addition to the above properties, the Mosaic Gold adds the invaluable one of not easily tarnishing or oxidizing, so that it may by simple means always be preserved in its original freshness and lustre.

"On this point a most decisive experiment has been made, by exposing several subjects, cast in Mosaic Gold, on the damp grass for eight weeks to the sea air, without any perceptible change or deterioration being produced in the colour; a fact which can be fully authenticated, and the particulars of which may be had of the pa

tentees.

"The Mosaic Gold is peculiarly applicable to the following articles, each of which forms an extensive branch of trade.

"Articles of plate and jewellery-salvers-plateaus― branches-wine coolers, &c.-candelabra-chandelierslamps-chimney-pieces-clocks-balusters for staircases -railings-architectural decorations-friezes and capitals of columns-statues and groups-bas-reliefs-vases -medals--enrichments for domestic furniture of various kinds carriage and harness furniture, &c. &c. &c.

"A valuable feature in this discovery, and most important as respects the Fine Arts, is, that from the metal being in itself, comparatively with gold, of small intrinsic value, liberal encouragement may be afforded for the

talents of our first artists, to make designs and models, from which articles in Mosaic Gold of unparalleled beauty may be manufactured; for all persons of taste who have visited the continent, and inspected the extensive manufactories of works of art in bronze, must lament how much we are excelled in this, perhaps the highest branch of manufacture; and it is therefore with pleasure the inventors can assure the public that extensive works, commenced under the most favourable auspices, are now erecting in the Regent's Park, which will afford every opportunity of attaining these desirable advantages.

"In order to place this invention on the most liberal plan, the Mosaic Gold will be sold to the trade in ingots, and licences may be obtained for working it."

Perpetual Motion.

A NEW project for a perpetual motion is about to be foisted upon the public, under the auspices and recommendation of a person who makes great professions of his scientific acquirements. The quackery of this individual has often obtruded itself upon our observation; but in the present instance, we are at a loss whether to attribute the imposition to sheer ignorance, or wilful deception though one who has followed the occupation of a machinist in a very delicate branch of the arts, should certainly know something of mechanical science, and therefore ought not to lead the unwary projector astray.

The inventor of this project is said to be a great but unlettered genius. It is amusing to see persons who

have not been able to surmount the difficulties presented in acquiring a knowledge of the alphabet, (for that is the fact,) coming forward to prove to us that mathematical science is a farce, - that gravity is a nonentity, and that an eternity of action is within the reach of human construction. Whether there is in the air that envelopes the ancient city of Norwich from whence this emanates, any thing particularly conducive to the growth of genius, we know not, but there has lately arisen out of the same precincts a cobler, who professes to prove the chronologies of Moses to be mere fabrications, and the philosophy of Newton downright nonsense.

The proposed perpetual motion under consideration, consists of two tanks, filled with water, in each of which there are five casks occupied with air; to the ends of a scale beam vibrating upon a standard between the tanks, there are two pendant rods attached, having extending arms at bottom, which are considered to be elongations of the lever above. The ends of the casks are made to slide in grooves along the tank, and power being in the first instance given to depress the beam at one end, and force down the upper cask to the bottom of the water at that side of the tank which is nearest to the fulcrum, the three casks at the bottom become displaced, and sliding along the groove, one of them rises at the most distant side of the tank, and by its buoyancy acting against the elongated lever, forces up the beam with more power than is sufficient to depress the cask at the nearest side of the other tank. In this way, when the machinery is once put into motion, it is to continue going without any assistance, and is not only to be self-moving, but to exert a surplus of power which may be employed as the moving agent of other machinery.

The fallacy of this scheme will be obvious to such of our readers as form a tolerable notion of the construction of the machine from this loose description; we shall, however, in our next give the particulars, with a plate.

Method of Preventing the Fracture of Glass Chimneys.

THE glass chimneys which are now in such extensive use, not only for oil lamps, but also for the burners of oil and coal-gas, very frequently break, and not only expose to danger those who are near them, but occasion very great expence and inconvenience, particularly to those who are resident in the country. The bursting of these glasses very often arises from knots in the glass where it is less perfectly annealed, and also from an inequality of thickness at their lower end, which prevents them from expanding uniformly by heat. The best method of detecting the knots is to examine the glasses by polarized light, and reject those that exhibit at the knots the depolarized tints.

M. Cadet de Vaux (Bull. des Sc. Tech. Mars 1825, p. 180,) informs us, that the evil arising from inequality of thickness may be cured, by making a cut with a diamond in the bottom of the tube, and he remarks that, in establishments where six lamps are lighted every day, and where this precaution was taken, there was not a single glass broken for nine years.

Polytechnic and Scientific Entelligence.

ASTRONOMICAL SOCIETY OF LONDON.

Dec. 9.-The President informed the Society that when he had the honour of announcing, at their last meeting, the extraordinary occurrence of the appearance of four comets in the short space of as many months, he was little aware that he might at that time have added a fifth to the number. This last comet appeared, from the account stated in the public journals, to have been discovered by M. Pons, at the beginning of last month; but, as it had considerable south declination, and was advancing also to the southward, and at the same time very faint, it probably would not be seen in this country.

Although the appearance of so many comets in one year had been mentioned as a remarkable phenomenon, yet he would not wish to be understood as supposing that such a circumstance had never previously occurred, nor was likely to occur again. The fact was, that from the great attention which had been paid by astronomers to the discovery of these bodies within these few years, and the interest excited by the investigation of the laws by which they were governed, a more than ordinary di