THE WOOLWICH BALLOON ASCENT. 
409 
due to the working of the vertical propeller, a doubt arose as 
to the exact balance of the balloon, which might have a ten- 
dency to rise and only have been held down by the captive line, 
which, except at very still moments, was pulled taut by the 
wind acting on the balloon. It being ascertained at a still 
interval that the balance was good, the vertical gear was worked 
and the balloon again rose. The rate of ascent was difficult to 
estimate ; it was judged, however, not to exceed 50 feet a 
minute. A positive indication of the power of the propeller 
was thus obtained, and it should be noticed that the circum- 
stances, if the rate of ascent only was measured, were rather 
disadvantageous, for the weight of the line, up to the extent of 40 
feet, was gradually added to the balloon as it rose. Had the mean 
rate of ascent and descent been taken, this error would be elimi- 
nated, for the descent would be favoured by the weight of the 
rope from 40 feet in length at the maximum height, down to 
nothing at the ground. The balloon was now liberated ; not, 
however, until Mr. Bowdler’s vertical gear had become broken 
and unable to work. The wind’s direction in the meantime had 
been ascertained to be suitable by sending off a series of small 
pilot balloons, and the ascent took place. The horizontal gear, 
however, throughout the entire voyage, failed to give any satis- 
factory results ; even allowing that the effect was perceptible, 
it is impossible to lay much stress on it. Any force would 
give a perceptible effect if recorded with sufficient delicacy. 
There is no use in an insignificant effect unless it can be shown 
that means exist by which it could be increased sufficiently to 
bear a reasonable relation to the forces to which it is to be 
opposed, or with which it is expected to be compounded. 
It is hopeless to look for this from fans or propellers turned 
by hand, for a balloon must very frequently expect to encounter 
currents of air that carry it along at least at ten miles an hour. 
Any motion produced by the force of a man’s arm, even at 
right angles to such a velocity, could hardly produce a sensible 
deviation from the direction in which the balloon is borne, and 
so could hardly show any sensible result in steering it. If, 
however, the more ambitious problem be attempted of pro- 
pelling a balloon in any desired direction, a power of an 
entirely different magnitude is required. The bulk of the 
balloon is enormous in proportion to the weight it carries ; 
hence it is necessary to provide a source of vast power, which 
shall be almost without weight, and hence the idea of any 
kind of engine, in the ordinary acceptation of the word, may 
be at once dismissed. The question arises, Have we a con- 
ception of the possibility of any great power existing in so 
light a form ? This, at all events in a degree, may be answered 
in the affirmative. There exist compositions, somewhat of the 
