20 
purpose, because of its lightness, and its capacity for holding gas. 
Strength could be obtained by combining layers of the substance 
by an ingenious arrangement devised by the Royal Engineers. 
One or two miniature balloons of. different sizes were quickly 
filled with gas from a compressed gas cylinder, and released by 
the lecturer, to sail up to the roof of the Banqueting Room at the 
end of a bit of string. To show how the perforation of a balloon 
by bullets would not necessarily mean disaster, if the perforations 
were in the lower part, Mr. Bruce pricked one of his bigger 
models with a lady’s hat pin. Though with this weapon he 
repeatedly stabbed the balloon, it continued calmly to ascend. 
At Ladysmith, he said, a war-balloon was actually brought down 
by a shell, but it came down so gently that there was no incon- 
venience at all to the officers in it. 
From the balloons themselves Mr. Bruce went on to illustrate 
a system of signalling by means of illuminated balloons, a system 
of his own invention which, he said, had been adopted by the 
British, Belgian, and Italian Governments, and he pointed out 
how useful balloon signalling might be in the case of ships distant 
from each other at sea, for detachments of an Army separated on 
land, and for polar exploration. The next experiments shown to 
’ the audience showed the action of erial screws, the means by 
which at present most zronauts are seeking to solve the problem 
of really navigating the air independently of the direction of the 
wind. One of the most interesting of the experiments, and one 
which called forth the hearty applause of the audience, was the 
releasing of a model of the Santos-Dumont steerable balloon, 
which, propelled by a little screw, made a circle gracefully in the 
air, and a trip to the big central chandelier and hack, a few feet 
over the heads of the spectators. 
In order to navigate the air, it was of the greatest importance 
to improve our knowledge of the numerous zrial currents at 
different altitudes. The disastrous results that may attend 
eeroplanes from these currents were illustrated experimentally by 
the convolutions in the Banqueting Room of a little flying 
machine. Mr. Bruce announced that, with a view to solving if 
possible some of the difficult problems connected with air 
currents above 3,oooft., arrangements were in progress for holding 
at an early date a great international kite-flying competition. The 
experiments, which would probably take place near Brighton, were 
likely to prove the most important of the kind in the history of 
eerial investigation. 
In conclusion, Mr. Bruce expressed his increasing conviction 
that the conquest of the air, when it was achieved, would be 
achieved along the lines of a natural simplicity. 
