. 800 Miscellaneous Intelligence. 
public buildings, may be truly said to have brought gas illumination to 
perfection ; for not only are all the products of combustion conveye 
_ at onée into the open air, but nearly the whole of the heat is in like 
- manner prevented from communicating itself to the atmosphere of the 
e only obstacles to the universal adoption of this description 
. of burner are its expense, and the difficulty of conveying the ventila- 
ting tube safely into the nearest flue without injuring the architectural 
appearance of the room. The public at large will therefore still await 
f . 
the removal of the objectionable compounds in question, by the gas 
manufacturer, before they will universally adopt this otherwise delight- 
ful means of artificial illumination. E. F. 
8. Mechanical Action of Heat ; by F. A. P. Barnanp.—Prof. Dana: 
—An apology is perhaps due from me to Mr. Rankine, for attributing 
exclusively to another, in my article on ‘ Heated Air,” sent you in 
ovember last, but published in March, a formula of thermo-dynamics 
oule in this respect, whose article on the ‘ Economical 
ume containing Mr. Rankine’s original paper, and had not received it, 
gu 
in question in the Lond. Phil. Trans., Part I, of the same year. In the 
paper first mentioned, the formula is not only deducible from the ex- 
pression cited by Mr. Rankine in the last number of this Journal,” viz.» 
1 ait 
Ww er 
—_ =} — dt 
EF st gS ee 03 
but it is actually deduced, by combining with the foregoing Mr. Joule’s 
Jar i 
_ when W and H are taken as above to represent the total motive power 
gained, and the mechanical equivalent of the total heat expended, 
severally, 
wW_S—T 
ee 
BT 
where Sand T are the thermometric temperatures of the source se 
heat and of the refrigerator respectively, and E is the reciprocal of the 
number of degrees between the absolute and the thermometric zeT0- 
It is evident that this, when the symbols employed by me to denote 
ope oe a ie tis ike etbedbicl as given in the last number of 
this Journal, Re: 

