Pure hydrogen prepared according to the method of the celebrated Henry Gifford filled the enormous balloon.

And as the capacity of the "Go-Ahead" was 40,000 cubic meters, the ascensional power of the gas she contained was 40,000 multiplied by 1,100 or 44,000 kilograms.
On this 29th of April everything was ready.

Since eleven o'clock the enormous aerostat had been floating a few feet from the ground ready to rise in mid-air.

It was splendid weather and seemed to have been made specially for the experiment, although if the breeze had been stronger the results might have been more conclusive.

There had never been any doubt that a balloon could be guided in a calm atmosphere; but to guide it when the atmosphere is in motion is quite another thing; and it is under such circumstances that the experiment should be tried.
But there was no wind today, nor any sign of any.