408 
POPULAll SCIENCE EEVIEW. 
Bowdler undertook a most formidable task. The apparatus by 
which he proposed to accomplish it is shown in Plate CXV. The 
machine consisted of two fans or propellors, one to give motion 
in the horizontal, and the other in the vertical direction, either 
being worked by a hand- winch, with multiplying gear. The 
entire apparatus weighs only about 701bs., the fans being made 
of very thin sheet metal. The highest speed with which the 
propellers may be made to revolve is from 600 to 720 revolu- 
tions per minute. The one on the vertical axis (c, Plate CXV.) 
is intended to cause the balloon to ascend or descend without 
loss of gas or ballast. The fan b, on the horizontal axis, is 
meant to give motion in the horizontal direction ; as, however, 
this may be in any accidental position, a rudder, a, made of 
canvas with strengthening bands, is fixed opposite to it, being 
held in the desired position for guiding by means of the rudder- 
lines. Mr. Bowdler considered that Mr. Coxwell’s balloon, which 
contained about 60,000 cubic feet of gas, was too large to be 
worked properly by the gear he had made ; he hoped, how- 
ever, that a sufficient result would be obtained to show its 
efficiency. 
The method of attaching the apparatus to the car by lashings 
is sufficiently shown in the sketch, the only part which is not 
seen being the hand-winch and some of the pinions, and about 
these there was nothing specially characteristic. 
An official programme, to be carried out at the trial, had been 
drawn up to the following effect : — (1st) The balloon, when held 
captive by a rope, was to be carefully balanced, and, if possible, 
raised and lowered repeatedly to the extent of about 150 feet, 
by means of the vertical propeller, in order to test its efficiency. 
It was also to be moved horizontally to and fro. (2nd) The 
balloon was to be released, and as soon as the course was shown 
to be steady, and the direction ascertained by means of Mr. 
Coxwell’s indicator, by maps, &c., the horizontal propeller was 
to be worked at right angles to the course of the balloon, and 
by this means the maximum effect when unopposed by any 
wind was to be noted. (3rd) The balloon was to be again raised 
and lowered by the vertical propeller, without throwing out 
ballast, or allowing gas to escape. 
Major Beaumont, Mr. Coxwell, Mr. Bowdler, and a sergeant 
of the Royal Engineers, entered the car, which was carefully 
balanced, and the first part of the programme was commenced, 
the balloon being held captive. Owing to a deficiency of suit- 
able rope, the raising was only carried out to the height of 
about 40 feet instead of 150. The difficulty of ascertaining 
exactly when a captive balloon is balanced, when even a slight 
wind is blowing so as to stretch the retaining rope, made the 
first trial a little doubtful ; and after one ascent, apparently 
