328 On Aérial Navigation. 
weight of the steam-horse be deducted, there will remain 1750 
pounds, which will, according to these estimates, be the weight 
of inert cargo in terms of horse powers which would he conveyed 
by this means. This is not a correct mode of estimating the 
matter in question; but J wish to show, by entering into this com- 
parison of animal and engine power, how very much the latter 
exceeds the former in energy, weight for weight; and that even 
if the estimates should be so false as to be five-fold wrong, yet 
there would be sufficient power for the purpose. I shall deduct 
three times the weight of the engine estimated in the note from 
the 50 tons of power unoccupied in the balloon, when there will 
remain rather more than 34 tons of power for any purpose re- 
quired. ‘This would convey 500 men during one hour, 410 men 
during 12 hours, 290 men for 24 hours, and 50 men for 48 
hours, without fresh supplies of fuel or water. The extent of 
the voyage in calm air would in the latter case be 960 miles. 
I do not offer this statement with any expectation of its being 
realized in our age; but I do affirm that balloon navigation does 
hold out the capabilities I have so daringly ventured to investi- 
gate; and I trust that others will join Mr. Edgeworth and my- 
self in promoting experiments upon a subject that promises 
eventually such advantage to mankind; the progress of civili- 
zation being evidently commensurate with the facility of com- 
munication. The expense of constructing the Montgolfier 
balloon described in my former paper, if.taken at three shillings 
per yard including the machinery, would be 870 pounds, and 
probably 1000 or 1500 pounds would defray the expenses of the 
experiment. The double cloth of the hydrogen gas balloon at 
six shillings would cost 3600 pounds, and the engines, &c. say 
from 6 to 7000 pounds ; so that this immense fabric, when com- 
pared to the large ships it seems to outvie, is not a tenth part 
of their cost. Their expense, however, when compared with 
their freight, will be about 300/. per ton. The, formation of 
hydrogen gas by the usual process is slow and expensive ; but by 
keeping fresh supplies of iron borings red hot within an exten- 
sive cavity properly constructed, and passing steam through the 
hydrogen gas, may be supplied at a very cheap rate, and with 
considerable rapidity. 
The vast strides which science of every kind has made within 
the last twenty years renders every advancing step more easy; 
and it appears to me that England may soon have the honour 
of perfecting the construction of balloons, although the inven- 
tion of them was not altogether her own. The heavy expense, 
however, of such extensive experiments renders it necessary that 
it should become a national object ; and as the means of di- 
recting balloons are within the scope of information of almost 
every 
