Southern's Experiments on Steam. \ 13 



if ^ = 5^5 the last equation becomes 



Then 



z=(D + hx^D') u = s-T^D' DsT-'d' (/^ ax + ^ [y]) . 



Examples might be given of reduction to a more simple 

 form of the same order. 



The omission of the factors 



x-uw+k'^yp, x~'{w+'2m+2k^)-p, &c. 



before the cipher of the second member of the equations 

 treated of in my paper in the Number of this Journal for 

 December last was an oversight, which I did not discover till 

 I received the January Number, notwithstanding the present 

 paper was composed immediately after it. 

 Gunthwaite Hall, Near Barnsley, Yorkshire 

 Jan. 12, 1847. 



XXIV. Mr. John Southern's Experhne7its on the Density, 

 Latent Heat and Elasticity qfSteam'^-. 



To Richard Taylor, Esq. 

 Dear Sir, 

 TN the various statements which have been published and 

 -*- re-published from time to lime respecting the nature and 

 properties of steam, the experimental investigations of Mr. John 

 Southern have not become so generally known as they deserve 

 to be, and if you can find space in your Magazine for reprint- 

 nig his papers they would convey useful information to your 

 readers. 



Mr. Southern was an able mathematician f, who was re- 

 tamed by Mr. Watt in the manufactory of steam-engines at 

 Soho, for the purpose of assisting him in investigating the best 

 proportions of the various parts of those machines, and cal- 

 culating the requisite dimensions which (according to the 

 ascertained strength of the materials employed) would give 



• *, ^^7faMmportant recent investigations of this subject will be found 

 in the 4th Volume of Taylor's Scientific Memoirs, just completed, amon" 

 which may be mentioned lloltzmann on the Heat and Elasticity of Case's 

 and Va|)oiirs, and on the principles of the Theory of Steam- Engines • 

 Ma-nus on the Expansive Force of Steam ; and on the Force requisite 

 for the production of Vapours ; and liegnault on the Elastic Forces of 

 Afpieous Vapour. — Ed. 



„,!, '"^h. .Southern contributed two papers to the early volumes of the 

 I hilosophical Magazine. Vol. xi. p. 97, and xvii. 120. 



