Windsor in the presence of King George III., Queen Charlotte, and the royal family. About this time (1784) balloons became "the fashion," and frequent instances occur of their being raised by day and night, by means of spirit-lamps, to the great delight of multitudes of spectators.
A letter from Watt to Dr. Lind, of Windsor, dated from Birmingham, 25th December, 1784, narrates an experiment made the summer preceding with a balloon inflated with hydrogen. The balloon was made of fine paper covered with a varnish of oil and filled two-thirds with hydrogen gas, and one-third common air. To the neck of the balloon was attached a sort of squib two feet long, the fuse of which was ignited when the balloon was inflated. The night was calm and dark, and a great multitude was assembled to witness the ascent, which was accomplished with a success that gave delight to all; for, at the end of six minutes the fuse communicated with the squib, and the explosion was like the sound of thunder. The men who saw it from a distance, but were not present at its ascent, took it for a meteor. "Our intention," says Watt, "was, if possible, to discover whether the reverberating sound of thunder was due to echoes or to successive explosions. The sound occasioned by the detonation of the hydrogen gas of the balloon in this experiment, does not enable us to form a definite judgment; all that we can do is to refer to those who were near the balloon, and who affirm that the sound was like that of thunder."
