S&6 Prertcfc Katlbnal Injlitiili. 



the author; and this' letter will not be opened, unlefs One" of 

 the prizes, or fome other reward, (hall be adjudged to him. 



All communications to be addrefled to Lord Carrington^ 

 prefidentj Sackville-ftreet. 



FRENCH NATIONAL INSTITUTE. 



The following account of the labours of the P.hyfical and 

 Mathematical Clafs during the laft three months of the 

 year 8 was read by C. Delamhre. 



C. Meiffier has given a curious eomparifon of the futnmcr 

 of the vear 1800 and that of the vear 1792. It remits frorii 

 his obfervations, that if the duration of the heat was nearly 

 the fame at each of thefe periods, it is Certain that in the 

 year 1792 the thermometer kept, pretty conftantly, two de- 

 grees and a half higher than in the year 1800; but what 

 renders the laft fummer more remarkable is, the extraor^ 

 dinary lownefs of the water of the Seine* 



In the year 1792, the water, for two months and a half, 

 kept, pretty conftantly, at about an inch above zero of the 

 fcale on the bridge de la Tournelle. During four days only, 

 it funk fo low as zero. On the nth of Auguft laft it was 

 (till lower by 4/9 inches. On the 20th of Auguft it was 

 even 7-65 inches below zero. It appears, then, that in the 

 vear 1800, the depreffion of the water of the Seine was fonie- 

 thing more than fix inches greater than it was in 1792. 



The year 1719 was remarkable alio for a long drought and 

 depreffion of the river. During the whole of that year there 

 fell no more than nine inches four lines of water at the ob~ 

 fervatory of Paris, which is not the half of the ufual quan- 

 tity. The depreffion of the water appeared then fo extraor- 

 dinary, that, to preferve the remembrance of it, the fcale of 

 the bridge La Tournelle was conftruiSted. This precaution, 

 however, did not prevent us from having 325 millimetres of 

 uncertainty in regard to the level of the Seine at that period. 

 According to Parcieux, the depreffion of the wafer in 1719 

 was indicated by the zero of the fcale. According to liuache, 

 it correfponded to the firlt foot of that fcale. Meiifier is in- 

 clined to adopt the latter indication. But however this may 

 be, it is certain that in the year 189Q the river, fell lower 

 o. than 



