340 Mr. Exleys New Demonstration, ^c. 



pressing force, within certain limits, has been long estab- 

 lished : it was usually called the Boyleian law, but now 

 the law of Mariotte. Sir I. Newton, in the Principia, 

 b. ii. p. 22, Sch., says, " But, as to our own air, this is 

 certain from experiment, that its density is either accurately 

 or very nearly as the compressing force." Modern philo- 

 sophers have removed some sources of error, and verified 

 the truth of the proposition through a very extensive scale 

 of compression. 



Now, it must be considered as a strong evidence of the 

 defects of every received theory, that none afforded a solu- 

 tion of this simple phenomenon, not even when applied by 

 the powerful mind of Newton, or Laplace, or the host of 

 great names which have graced the annals of science since 

 the times of Boyle and Newton. Hence, this proof of the pro- 

 position must be considered as sufficient of itself to stamp a 

 character of truth on the theory from which it is obtained. 



The corollaries are added as easy deductions, and because 

 most of them are experimental results, not previously 

 demonstrated from theory, the pressure at T may be con- 

 sidered as representing temperature ; for it is very probable 

 that ethereal matter at rest is insensible caloric and absorbed 

 light ; and the same in motion is sensible caloric, or light 

 according to its velocity : see my Treatise on ** Physical 

 Optics." The terrestrial atmosphere, according to this 

 theory, consists of tenacious atoms separated by ethereal 

 matter, which extends, perhaps, several hundreds of miles 

 above the highest stratum of tenacious atoms ; and this 

 ethereal matter will produce a pressure similar to that of 

 T in common circumstances ; while the same augmented 

 or diminished by local causes answers to the same pressure 

 exerted in a greater or less degree. 



According to this rational view, cors. 2, 4, 5, 6 and 7, 

 are theoretical proofs of well known experimental facts, 

 which, I presume, cannot be explained on any other general 

 principles. With jny best respects, 



I remain, dear sir, yours truly, 



Thomas Exley. 



Bristol, Oct. 7th, 1836. 



Errata in last Number, page 277, line 4 from bottom, for two read three. 



„ 28.0, "„ 6 from top, for 16+16 read 14-f 16. 



