458 Artificial Flight: An Aérial Ship. [October, 
taffetas covering of the balloon which was found to be yuite 
impervious to water. This varnish has gelatine for its base, 
and is prepared from two solutions, termed A and B 
respectively. A consists of 1 part of pure gelatine, I part 
of glycerine, 6 parts of pyroligneous acid. B consists of 
I part of tannin, and pyroligneous acid 6 parts. The gly- 
cerine is dissolved in the pyroligneous acid by the aid of 
gentle heat, and while warm A is poured into B, the mixture 
being stirred with a wooden spatula. ‘The mixture is re- 
heated in an open vessel for some time, acid being added as 
that in the mixture is evaporated. The balloon consists of 
white silk taffeta, lined with india-rubber, and again with 
nanzouk; and to the nanzouk lining the composition is 
applied. 
M. de Lome’s attempt, although so eminently successful, 
cannot be characterised as ambitious, because, instead of 
depending upon speed for the hold of the machine upon the 
air, the object was the very modest one of giving to a 
balloon, of the best shape and dimensions, a velocity of 
about 8 kilometres with regard to the surrounding air. “Ehis 
being attained the same aérostat would, of course, when 
impelled by the wind, move at a more rapid rate ; thus, with 
a iresh breeze, at the rate of 4 metres per second, tae 
aérostat would be perfectly under command within an angle 
of 33 on each side of the wind’s plane, or within a sector of 
66°. And if we double the rate of movement of the wind, 
we must inversely halve the angles within which the 
aérostat may be considered safely under control. That the 
plane of movement shall be dire¢tly under the control of the 
aéronaut requires that much less resistance should be pre- 
sented to the air than is the case with the ordinary balloon, 
and careful calculation led to the following dimensions :— 
Length, 36°12 metres (118 ft. 6 in:); diameter at-cemene. 
14°84 metres (48 ft. 8 in.); the area of section through the 
centre being 172°96 square metres (1862 square feet), and 
the volume 3454 cubic metres (121,983 cubic feet). Merde 
Lome, in his original paper, shows that to obtain a speed of 
8 kilos. (about 5 miles per hour) it is necessary to maintain a 
motive power equivalent to 30 kilogrammetres (or 217 foot- 
pounds) per second, this motive power being preferably 
obtained from manual labour utilised in rotating a shaft to 
which is attached a two-bladed screw. In this case, if we 
take R to represent the resistance of the atmosphere at a 
speed, s, of the balloon in seconds, d the diameter of the 
screw, p the pitch of the screw, and » the number of revo- 
lutions per minute, then 
