Mr. D. Gilbert on Ventilation. 113 



find something analogous to the effects of the same inanimate 

 agent acting on inanimate matter, in the latter nothing analogous 

 to any of the effects of such an agent. 

 [To be continued.] 



Art. X. On the Ventilation of Rooms, and on the Ascent 

 of heated Gases through Flues. By Davies Gilbert, 

 Esq., F.R.S. 



[la a Letter to the Editor.] 



Dear Sir, — The following investigations were made several 

 years ago, on the occasion of ventilating both houses of par- 

 liament, with the hope of discovering some principle, that might 

 guide architects in their attempts to change the air of crowded 

 apartments; an object of considerable importance to the health 

 as well as to the comfort of all persons frequenting such 

 places. The same formulae apply to the ascent tif gas from 

 furnaces : the whole is, however, such a mere trifle in respect 

 to science, that I should not have entertained a thought of 

 troubling you with it, were I not persuaded that the conclusions 

 will be found of some practical use. 



In this, as in all such attempts, the most simple cases must 

 be selected for calculation, leaving their various complications, 

 modification, and local circumstances to the judgment and di- 

 rection of each individual operator. 



Let atmospheric air, or any gas be supposed to ascend 

 through smooth, even, and regular tubes, with an equable tem- 

 perature, and consequently with the same rarefaction through- 

 out. 



Let X := the rarefaction. 



g — the specific gravity of the elastic fluid, as compared 

 with atmospheric air. 



then — the density. 



h ~ the height of an uniform atmosphere 26058 feet, 



log. 4.4159412. 

 m = the velocity with which atmospheric air rushes into 

 a vacuum, or 1295 feet in a second, log. 3.1 122698 

 Vol. XIII. I 



