574 HISTORY OF THERMOTICS. 



equal to that of the atmosphere. Schmidt at Gies- 

 sen endeavoured to improve the apparatus used by 

 Betancourt; and Biker, of Rotterdam, in 1800, made 

 new trials for the same purpose. 



In 1801, Mr. Dalton communicated to the Philo- 

 sophical Society of Manchester his investigations 

 on this subject ; observing truly, that though the 

 forces at high temperatures are most important 

 when steam is considered as a mechanical agent, 

 the progress of philosophy is more Immediately 

 interested in accurate observations on the force at 

 low temperatures. He also found that his series of 

 elasticities for equidistant temperatures resembled 

 a geometrical progression, but with a ratio con- 

 stantly diminishing. Dr. lire, in 1818, published 

 in the Philosophical Transactions of London, ex- 

 periments of the same kind, valuable from the 

 high temperatures at which they were made, and 

 for the simplicity of his apparatus. The law which 

 he thus obtained approached, like Dalton's, to a 

 geometrical progression. Dr. Ure says, that a for- 

 mula proposed by M. Biot gives an errour of near 

 nine inches out of seventy-five, at a temperature 

 of 266 degrees. This is very conceivable, for if 

 the formula be wrong at all, the geometrical pro- 

 gress rapidly inflames the errour in the higher por- 

 tions of the scale. The elasticity of steam, at high 

 temperatures, has also been experimentally ex- 

 amined by Mr. Southern, of Soho, and Mr. Sharpe, 

 of Manchester. Mr. Dalton has attempted to 



