CONTENTS. Yii 



DECEMBER 1807. 



"Engravings of the following Objeccts : 1. On the Construction of GovcFod Wajs^t 

 2. Sir John Caviey's Expansion Air Engine. 



I, Remarks on the Structure of- covered Ways, independent of the Pririciblef of 

 the Arch in Equilibrium, and on the best Forms for Arches in Buildings, 

 From a Correspondent (Apsophus) - - - - 241 



IE Additional Remarks on the capillary Actions of Fluids. By Aletes. 250^ 



III. On a Kind of DeatJi, that may be presumed to be only appaj-ent. By Mr. 

 ' Du Pont de Nemours. Read at the First Class of the Institute, October 28, 



1806 - - - « ... . .2H^ 



IV. Description of an Engine for affording Mechanical Power from Air ex-, 

 panded by Heat. By Sir George Cayley, Bart. - - 26<y 



V. A Letter from Mr. Robert Harrup to the Editor, on the Diseases of Wheat 



2Q2f 



VI. Description of a simple and convenient portable Electrometer for Mineral- 

 ogists. In a Letter from a Correspondent . - - 27 Q- 



VII. A Method of sowing Clover^ and a new Plan for a Rotation of Crops. 

 By Mr. de Vincens, of Th<»de, near Clermont - - 271 



VIII. A Memoir on Roman Alum, compared with different Kinds manufac- 

 tured in France. By Messrs. Thenard and Roard. Abridged by Mr. Bouil* 

 lon-Lagrange . - . . _ 275 



IX. Essays on the Improvement of Pottery in general, or the Art of making, at 

 the least Expense. Vessels for eveiy Use, more handsome, strong, and whole- 

 some, without ei7iploying Lead or Tin, in the Composition of the Coatings 

 Enamel, or Glaze. By Mr. C. R. Jousselin, Manufacturer at Nevers. An 

 Abstract by Mr. Guyton - - - - 251. 



K. Process for proving the Quality of a Glaze of Earthen Ware - 294 



XI. Heights of various Places in France, &c. By Dr. Berger - 295 



XII. Transformation of Mr. Dubuat's Hydraulic Theorem. By Thomas 

 Young, M. D. F. R. S. - - - - 309 



XIII. Observations on the Theory of Ear Trumpets, with a View to their Im- 

 provement. ByJohnGough, Esq. - - - - 310 



XIV. Report made to the Mathematical and Physical Class of the Institute, on 

 a Memoir of Mr. Descotils, relative to Iron Spar. By Messrs. Berthollet, 

 Lelievre, andVauquelin - - - • 315 



Scientific News * * • % » 32d 



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