22 Mr Henry Meikle's Remarks and Experiments 



botanical drawings of new plants, that had been commenced in 

 the Royal Gardens at Kew, by the excellent artist Mr Bauer. 



Sir Joseph Banks died on the 19th May 1820, leaving no 

 issue. The Royal Society elected for their President Sir Hum- 

 phrey Davy, who will equal him in all his good qualities, and 

 who will not give rise to the same objections ; for, young as he 

 still is, his discoveries are among the most admirable of the age. 

 Sir Humphrey Davy was already before this a foreign member 

 of the Institute ; and the Academy of Science has named, in the 

 pla^e of Sir Joseph Banks, M. Gauss, Professor of Gottingen, 

 to whom his excellent labours in the mathematics long gave a 

 title to that honour. 



Remarks and Experiments relating to Hygrometers and Eva- 

 poration. By Mr Henry Meikle. Communicated by the 

 Author. 



XT is now pretty generally admitted, that hygrometers, formed 

 of absorbent substances, being necessarily of a changing or pe- 

 rishable nature, are extremely liable to have their sensibility im- 

 paired through length of time ; so that little confidence can be 

 placed in them, however accurately they may have been at first 

 constructed. Nor is there much reason to expect that two such 

 hygrometers will agree, unless the one have been made from the 

 other, or both have been graduated from some less vague instru- 

 ment ; but even admitting that they did agree, what security 

 have we that such accordance shall continue ? Professor 

 Leslie's hygrometer is entirely free from this objection, as like- 

 wise Mr Dani ell's, and some modifications of it proposed by 

 Mr Jones and others. The principle of the latter sort is to cool 

 down an even or polished surface exposed to the air, till a de- 

 position of moisture begin to adhere to it ; and if we could 

 easily and accurately ascertain this reduced temperature, we 

 should be enabled to determine the state of the air with regard 

 to moisture. The cooling principle here employed, as the most 

 convenient, is the evaporation of ether ; and for that purpose, a 

 supply of this costly liquid, of rather a superior quality, must be 

 constantlv carried along with the instrument. 



