320 Proceedings of the British Association. 



fluence of the stars. Under the head of press^tre, the barometer, 

 its construction and proper use, came under consideration. He 

 pointed out the use of curves in recording and comparing its indi- 

 cations, — the great variety of its oscillations in the several parts 

 of the earth, and the importance of accurate registers of its indi- 

 cations being kept, — alluding to the value of the hourly observa- 

 tions recorded, for so many years, under the inspection of Mr. 

 Snow Harris, at Plymouth, and those at Leith and other places 

 in Scotland, under the inspection of Sir D. Brewster. He next 

 referred to a fact which seems to lead to the inference, that we 

 must repose less confidence in the barometer as a means of meas- 

 uring heights than has been heretofore supposed. It has been 

 found by actually leveling between the Black Sea and the Cas- 

 pian, that the latter is only 82 feet below the level of the former ; 

 whereas barometric measurements, founded on previous deter- 

 minations, since carefully repeated, gave, in consequence of 

 some unknown anomaly, the difference of 320 feet. The hu- 

 midity of the atmosphere was the next topic discussed. As to 

 the amount of vapor in the air, at any one instant, he considered 

 that by the researches of Dr. Apjohn. begun at the suggestion of 

 the Association, the important problem of the wet-bulb thermom- 

 eter had been completely solved, and meteorologists thus put in 

 possession of a simple and most effective instrument. The distri- 

 bution of humidity in the atmosphere was next noticed. Under 

 the head of wiiid, he alluded to the theory of Dove, which he 

 said was comparatively unknown in these countries ; and briefly 

 spoke of the researches of Lieut. Col. Reid, Mr. Rediield, and 

 Mr. Espy. Passing over the topics of clouds and raiii, he prom- 

 ised to bring forward on a future day, some facts connected with 

 extraordinary falls of rain which had been observed ; but which, 

 as stated by him, in one instance in his former report, had been 

 in his absence called in question. Regarding electricity, he ob- 

 served that Httle had been added either to our instrumental re- 

 sources, or to our knowledge of the subject, since his former re- 

 port. On the subject of meteors, the report contained all the re- 

 cent information concerning the unusually numerous appearance 

 of those which had been seen for some years, on the 12th and 

 13th of November, and 10th of August ; and concluded by point- 

 ing out the advantages of public meteorological observations for 

 the purpose of, 1st. determining laws : 2d. keeping, and under 



