344 Professor Leslie's Discovery. 



mination of the unkuovvn quantities be at all times possible, 

 and by what mode of calculation it may be rendered practi- 

 cable, in certain cases in which it does not appear to be so. 

 He adds, that this subject may give rise to several neat 

 analytical inquiries, to enter upon which would carry him 

 too far from his principal object : he postpones, therefore, 

 to another occasion the methods of reducing numerical 

 calculation to a more expeditious algarithm. After the ex- 

 ample of M. Legendre, he entreats calculators not to seek, 

 in the determination of the known co-efficients, a pre- 

 cision which can only serve to lengthen the operations in a 

 useless manner. 



XXXV. Intelligence and Miscellaneous Articles. 

 PROFESSOR Leslie's discovery. 



1 HE experiments of Professor Leslie, to produce ice by 

 evaporation in the air pump, have been varied and extended 

 in France by Messrs. Clement and Desormes: they have 

 proposed to apply the evaporation, in vacuo, on a large 

 scale, to the drying of gunpowder j which, being done 

 without fire, will be attended with no danger. 



The French chemists are engaged in endeavouring to ap- 

 ply the evaporation in vacuo (before stated) to the drying and 

 preserving fruit and vegetables. It may be easily conceived 

 of what advantage this process may be, particularly in the 

 army and navy, by preserving, unchanged, alimentary sub- 

 stances, and also by diminishing their weight and bulk, 

 when they are to be sent to distant parts of the world. 



In consequence of this paragraph, we observe that Mr. 

 Leslie has addressed a letter to the Editor of the Caledonian 

 Mercury, and we can bear testimony to the truth of the 

 Professor's claims to the discovery; for we personally wit- 

 nessed the demonstration of his theory while in London 

 last year, when he freely explained the various important 

 uses to which the principle might be applied, particularly 

 by the introduction of the apparatus into hospitals in sultry 

 climates, and for its general utility in domestic purposes. 

 We understand that he has, since his return to Edinburgh, 

 improved his coolers, so as to produce ice in large quan- 

 tities, by much inferior powers to those he first used. 



Dr. Kelly is now printing a New Edition (the fourth) 

 of his Spherics and Nautical Astronomy with considerable 

 additions, especially in what relates to the Lunar Observa- 

 tions, and Practical Astronomv in general. 



To 



