W CONTENTS. 



APRIL, 1801.. 



Engravings of the following Objefts : 1. A new Apparatus for fweeplng Chim-. 

 nies, communicated by ;he Inventor Mr. Hornblower; 2. Figures by Dr. 

 Htrrfchcl, to explain the Changes of Double Stars j 3. A Galvanic Apparatus 

 to atford the Maximum of EfFe6l in Combuftion, from I. R. I. a Coriefpon- 

 dent J 4. Anew Hydraulic Engine, which, by the Difcharge of Wafte Water, 

 raifes Freih Water to the Ap;a tments of a Houle, &c. by Mr. Sharpies. 



I. Experiments proving the Advantage of Perifcopic Spe(5kacles. Communi-' 

 cated in a Letter from W. H. WoUafton, M.D. F. R. S. Page 241 



II. Additional Obfervations on foOie remarkable Strata of Flint in the Ifle of 

 Wight, in a Letter from Sir Charles Englefield, Bart. F. R. S. to John La- 

 tham, M. D. F. R. S. and L. S. - - - 242 



III. Account of a Machine for fweeplng Chimnies by a Blaft of Air. In a Let-< 

 tcr from Mr. J. C. Hornblower, Engineer. - - 246 



IV. Account of the Changes that have happened, during the laft Twenty-five 

 Years, in the relative Situation of Double Stars j with an Inveftigation of 

 the Caufe to which they are owing. By William Herfchel, LL. D. F. R. S. 252 



V. Account of the Invention of the Compound Barrel and Winch, and its ufcful 

 Application on a large Scale. In a Letter from Mr. J. J. Hawkins. 267 



VI. Propofal for conltruding a Galvanic Apparatus of great Power, for the 

 Combuftion of Metals. By a Correfpondent. I.R.I. - 269 



VII. A Memoir concerning the Fafcinating Faculty which has been afcribed 

 to the Rattle-Snake and other American Serpents. By Benjamin Smith 

 Barton, M. D. - - - - - 270 



VIII. Extra6l of a Letter from Brugnatelli on the Pruffiate of Potafli, and on 

 the Preparation of a Fulminating Muriate of Silver. - 285 



IX. Of the Application of Platina or Porcelain. By Klaproth. 286 



X. Abftrafl of a Memoir on Galvanifm, fent to the National Inftitute by Mr. 

 ]R.itter, of Jena. . - . - - 288 



XI. On Speftacles, particularly the Perifcopic. In a Letter from Mr. E, 

 Walker. . - - - - - £91 



XII. Communication refpe6ling the Chay Root, a Species of Madder ufed for 

 dying durable Red Colours in the Eaft Indies. By John Stockweli, Efq. 294 



XIII. Delcription of an Apparatus for raifmg Water by the Fall of Wafte 

 Water. By Mr. Sharpies, Portrait Painter, Bath. Communicated by the 

 Author. - - - - - - 298 



XIV. On Gridiron Pendulum Rods compofed of Lead and Iron. By Mr. 

 Benzenberg. - - - - - 300 



XV. On the Advantages of a large Knife in making Pens. By a Correfpondent. ib. 



XVI. Communication refpe6ling an Article fenr from the Eaft Indies, under 

 the Name of Gum Kuteera, and of which a large Quantity has been lately 

 imported into this Kingdom. By Mr* John Cowie. - - 301 



XVII. Galvanic Experiments with Ice, and a Method of rendering the Eleftric 

 Attra6lion of the Pile very evident. By S. P. Bouvier, of Jodoigne, Mem- 

 ber of the Society of Emulation, of Natural Hiftory and Phyfics, at Bruf- 

 lels. - - - - - - 30J; 



XV III. Experiments on the A6Vivity of a Galvanic Pile, in which thin Strata of 

 Air are fubftituted inftead of the Wet Bodies. By Mr. Dyckhoff. 305 



XIX. Extract from a Letter from Mr. J. B. Van den Sande, Profeflbr at Lux- 

 embourg, on the Efflorefcence and Decompofition of Glals Tubes. 306 



XX. On the Criterions or due Difcriminations of Cyder Fruit. By Thomas 

 Skip Dyot Bucknall, Efq. - - - -.307 



XXI. Concerning the Steam Engine from Mr. Blakey, by a Correfpondent. B. 310 



XXII. Oblervationsand Conjmunications on the Dry Rot in Timber, made to the 

 Society for Encouragement of Arts. - - - 315 



Scientific News, 318. — Society of Agriculture, Commerce, and Arts, at Bou- 

 logne-fur-Mer, ib. — Cryftallization of Lime by Tromldorlf, denied by Ber- 

 thoUet, 319. — Converfion of Pieces of Cloth impregnated with a Solution of 

 Salt into Soap of Wool, by the Action of the Galvanic Pile. By Brugnatelli, 320 



