greater than 6 feet by 8, yet Mr Perkins considers that the apparatus (with the exception of the working cylinder PP, and piston PQ), is perfectly sufficient for a 30-horse engine. When the engine performs full work, it consumes only two bushels of coal in the day.

On the application of Mr Perkins's principle to Steam-Engines of the old Construction.

Great as the invention is which we have now described, yet we are disposed to think that the application of the principle to old steam-engines is not less important *. When we consider the enormous capital which is at present embodied in Great Britain in the substantial form of steam-engines, and the admirable elegance and skill with which these noble machines impel and regulate the vast population of wheels and pinions over which they reign, we feel as if some vast innovation were proposed upon our established usages, by the introduction of Mr Perkins's engine. The very idea that these potentates of the mechanical world should be displaced from their thrones; that their strongholds should be dismantled; their palaces demolished, and their whole affairs placed under a more economical management, is somewhat startling to those who dread change, and admire institutions that both work and wear well. Mr Perkins, however, has saved them from such a degradation. He has allowed them to retain all their honours and privileges, and proposes only to invigorate them with fresh influence and power.

In this new system, the old engines, with their boilers, are retained unaltered. The furnaces alone are removed. Mr Perkins constructs a generator consisting of three horizontal tubes of gun-metal, connected together, filled with water, and supplied with water from a forcing-pump, as in his own engine. This generator is exposed to heat in an analogous manner, so that, by means of a loaded valve, which opens and shuts, the red hot fluid may be constrained till forced out of the generator into the water in the boilers of Bolton and Watt. By this means, as much low pressure steam of four pounds on the square

This invention appears to have been fully established by direct experiment, whereas the new engine, with all its great promise, is still only undergoing trial. VOL. IX. NO. 17. 1823.

M

inch may be generated by one bushel of coals, as could be produced in the old engine by nine bushels. This most important result, was obtained by actual experiment.

Since these great improvements have been effected, Mr Perkins has made a discovery that seems, in its practical importance, to surpass them all. He now entirely dispenses with the use of the condenser, and works the engine against the atmosphere alone; and by methods with which we are not acquainted, and which indeed it would not be prudent for him to disclose at present, he is enabled to arrest the heat after it has performed its mechanical functions, and actually pump it back to the generator, to unite with a fresh portion of water, and renew its useful labours. In an operation like this, a considerable portion of the heat must still be lost, but the wonder is that any should be saved; and we venture to say, that the most sanguine speculator on the omnipotence of the steam-engine, never dared even to imagine the possibility of such an invention.

We are well aware, that, in announcing this discovery, we are exposing ourselves to the criticisms of those whose belief is naturally limited by their own experience; but it is satisfactory to know, that Captain Basil Hall, (whose account of Mr Perkins's discoveries and inventions, as delivered before the Royal Society of Edinburgh, gave such universal satisfaction,) has been entrusted with Mr Perkins's discovery, and that he speaks confidently of the soundness of its principles, as well as the practicability of its application *.

We cannot quit this subject, without congratulating the country on the brilliant prospects with which these inventions promise to invest all our national concerns. At any period of the history of British industry, they must have excited the highest expectations; but, originating as they have done, when our commerce, our manufactures, and our agriculture, the three stars of our national prosperity, have just passed the

* After the 10th June, Mr Perkins, whose address is Perkins and Company, 41. Water Lane, Fleet Street, is ready to take orders for his New Engines, and his apparatus for producing low pressure steam for working the ordinary engines. The price, we believe, of the new engine, is only half that of Bolton and Watt's, with one-third of the savings of fuel for a period of years, which we have not heard stated.

lowest point of their orbit, and quitted, we trust for long, the scene of their disturbing forces, we cannot but hail them with the liveliest enthusiasm, and regard them as contributing, to ensure the pre-eminence of our industry, to augment the wealth and resources of the nation, and, by giving employment to idle hands, and direction to idle minds, to secure the integrity and the permanence of our national institutions *.

ART. XX.-Abstract of Experiments on the Fusion of Plumbago, Anthracite, and the Diamond+. By Professor SILLI

MAN.

HAVING

AVING succeeded in fusing and volatilising charcoal by Dr Hare's Galvanic Deflagrator, Professor Silliman applied the same powerful instrument to plumbago, and subjected anthracite, and the diamond, to the action of the oxy-hydrogen blowpipe.

"From a piece," says he, " of very fine plumbago, from Carolina, I sawed small parallelopipeds, about one-eighth of an inch in diameter, and from three-fourths of an inch to one inch and a quarter in length: these were sharpened at one end, and one of them was employed to point one pole of the deflagrator, while the other was terminated by prepared charcoal. The best were obtained when the plumbago was connected with the copper, and prepared charcoal with the zinc pole. The spark was vivid, and globules of melted plumbago could be discerned, even in the midst of the ignition, forming and formed upon the edges of the focus of heat. In this region also, there was a bright scintillation, evidently owing to combustion, which went on where air had free access, but was prevented by the vapour of carbon, which occupied the highly luminous region of the focus, between the poles, and of the direct route between them. Just on and beyond the confines of the ignited portion of the plumbago, there was formed a belt of a reddish-brown colour, a quarter of an

It is due to the truth and candour of philosophical history, to mention, that Mr Perkins is not our countryman; but the age of jealousy against America has happily gone past, and we hail, with sincere pleasure, any circumstance which contributes to the scientific renown of our great descendants, and companions in free. dom and intelligence.

+ Professor Silliman has been so good as to forward to us an account of these very curious and highly important experiments, so as to reach us before the arrival of the Number (Vol. VI. No. 2.) of the valuable Journal in which they will appear. We would have published the full account of this inquiry, but the printing of this Number was too far advanced to admit of this. We trust that the following abstract will convey a complete idea of the results.