CONTENTS. vii 



APRIL, 1808. 



Engravings of the following Objects: 1. Mr. Barraud's Mercurial Pendulum: 

 2. Dr. Herschel on tUe Planet Vesta: 3. Mr. Tugwell's new Method of 

 Roofing Houses. 



I. On the formation of the Bark of Trees. In a Letter from T. A. Knight, Esq. 

 F. R. S. to the Right Honourable Sir Joseph Banks, K. B. P. R. S. &c 2-H 



II. On the Economy of Bees. In a Letter from Thomas Andrew Knight, Jmj. 

 F. R. S. to the Right Honourable Sir Joseph Banks, Bart. K. B. P. R. S. 250 



III. Description of a Mercurial Pendulum. Communicated by Mr. Barraud, of 

 Cornhill, who has made several, and has been highly satisfied with their Per- 

 formance in the Measure af Time - - - < 258 



IV. Observations on the Nature of the new celestial Body discovered by Dr. 

 Olbers, and of the Comet which was expected to appear last January in its 

 Return from the Sun. By William Herschel, LL.D. F. R. S. - 259 



V. Observations and Measurements of the Planet Vesta. By John Jerome 

 Schroeter, F. R. S. - - - - 264 



VI. On a new Method of Slating, and constructing the Roofs of Houses : by 

 Mr. Lewin Tugwell - - - 2Q0 



VIL Heights of various Places in France, &c. ; by Dr. Berger. Concluded 

 from Vol. XVIII, p. 308 - !272 



VIII. On the Cultivation of the Poppy. By T. Cogan, M. D. 282 



IX. On the Use of Tobacco Water, in preserving Fruit Crops, by destroying 

 Insects : and on the Use of the Striped or Ribband Grass. By Mr. Robert 

 Hallett ------ 298 



X. A second Letter from Mr. Robert Hallet, on the Efficacy of Tobacco Water 

 in destroying Insects, infesting Fruit Trees - - 301 



XI. Remarks on a Pamphlet, lately publi xed by the Rev. S. Vince, respecting 

 the Cause of Gravitation. By a Corre pondent. - - 304 



XII. Farther Experiments and Obse* .ations on Potash and its Base. In a 

 Letter from Mr. C. Sylvester - - - - 307 



XIII. An Account of the Measurer^ jnt of an Arc on the Meridian on the Coast 

 of Coromandel, and the Leng*\ of a Degree deduced therefrom in the La- 

 titude 12° 32', By Brigade Ma :>r William Lambton - 309 



Scientific News - * - - 317 



SUPPLEMENT. 



