ON KlXEa CASBSv 



that daii)'pracUce diMcIoses to the Industrious draftsman al! tf)« 

 arcana of optical, aei'eal, ar.d linear perspective, destitute, it is 

 true, of terms to describe his acquirement; but to his own mind 

 a perfectly intelligible and useful rule, by the help of which he 

 can, with certainty, imitate all he sees on the theatre oi the 

 universe. 



With respect and esteem, 

 I am, Sir, 



Your obliged humble Servant, 

 Bristol, DecA; 180?, G. CUMBERLAND, 



An Essay on the . Theory of mixed Gases, and the State of 

 Water in the Atmosphere. By Mr. John Gough.. Com- 

 municated by Dr. Holme. 



F< 



The Essays of Jj^ OUR essays appear in the fifth volume of the Memoirs of 

 verted to. * ^^^ Literary and Philosophical Society of Manchester, which 

 contain many new ideas relating to the constitution of mixed 

 gases, and the sate of water in the atmosphere. The design 

 ©f these papers is evidently intended to remove certain diffi^ 

 Gulties which must strike every man of science, who happens- 

 to peruse M. de Lue's Theory of atmospherical Vapour. This 

 attempt has the double recommendation of ingenuity and 

 novelty ; but the leading opinions of the system, even in its 

 present form, are liable to several objections, whicii I am 

 going to point out, being generously invited to undertake the 

 task, by the author himself. My doubts relative to the sub- 

 ject arise partly from mathematical considerations, and in part 

 from the evidence of experiment. Certain objections of the 

 first class dispose me to conclude, that an atmosphere construc- 

 ted on Mr. Dalton's plan, will appear upon examination to be 

 repugnant to the principles of the mechanical philosophy ^ 

 and a direct appeal to experiment has moreover convinced me,, 

 that well estabhshed facts contradict the essential points of the 

 theory. 

 Concise view To begin with the objections of the former class : I am 

 of Mr. Dalton's ready to admit the existence of a fluid mixture, such as we find 

 •dSs!'™''' <^®scribed at page 513, in the* fifth volume of the Manchester 



* See our JouroaU Vol, VI, g, 25T. 



