ed by the passengers on the route. 
e day trains, less heavy but more rapid, will conduct in about the 
same amount of air. 
The pure air thus derived in twenty-four hours, will be in the ratio of 
1:15 cubic meters per second, or 45 cubic meters per person. Halls of 
assembly are known to be exceedingly well ventilated when 10 cubic 
meters of pure air are received per man per hour. But the air of the 
tunnel, although it may be considered as confined air, will supply 10°056 
cubic meters of air to each man—supposing there be 2200 passengers 
per day and the time of transit 70 minutes. 
While then steam would soon affect respiration, there will be no ill 
effect in case of the use of compressed air for locomotion, No machine 
of this kind now exists, it is true, although its possibility has been de- 
monstrated. But when really required, they will soon be supplied. The 
occasion will present itself when the tunnel-of Mount Cenis shall have 
been constructed: its length is more than twelve kilometers, and only 
compressed air can be used. 
The means of compressing large quantities of air for locomotion are I 
believe very simple. In the case of the submarine tunnel there are the 
fires power rendered useless by the suppression of the steam locomo- 
tive; and besides, the winds may be used at the Pas de Calais and on 
air is al : 
by means of water-falls, which are abundant in the Alps. The machine 
The fall of water which moves it has a force of four horse power. Ina 
machine which is a steam engine of eight horse er; it furnishes in 
hours. But with a power like the wind, we can without too great cost 
multiply compressing machines and obtain by means of compressed air a 
moving power as economical as steam. —— 
* T calculate only for adults in good health, =a — with Dumas —_ such. 
grams ‘bon twenty-four hours (counting as car' a 
et mpi ne ais yeaa carbon correspond to 550 litres rf 
i yi passing un- 
then 145 grams of carbon Fs re 264 litres of car- 
Setids und in of 220 passengers, 5,830 litres; or ten trains with 2200 pas- 
- gengers in all, 58,300 litres, or six cubic meters. In these calculations I take the most 
re ie ‘cane: carbon is a maximum and Iti 
ge therefore to take into consideration the very interesting facts brought 
not | ie Senith (Phil. Mag., xiv, 547), and which establish, besides other chilies 
ig jes of oti bonic acid 
of different modes of locomotion on the quantity of 
