But there was one very important distinction between the two
air-ships. By a most ingenious contrivance the envelope was made
so that, in the event of a large and serious escape of gas, the
balloon would assume the form of a giant umbrella, and fall to
earth after the manner of a parachute.

All inventors profit, or should profit, by the experience of
others, whether such experience be gained by success or failure.
It was found that Santos-Dumont's air-ship lost a considerable
amount of gas when driven through the air, and on several
occasions the whole craft was in great danger of collapse. To
keep the envelope inflated as tightly as possible Mr. Spencer, by
a clever contrivance, made it possible to force air into the
balloon to replace the escaped gas.

The first Spencer air-ship was built for experimental purposes.
It was able to lift only one person of light weight, and was thus
a great contrast to the modern dirigible which carries a crew of
thirty or forty people. Mr. Spencer made several exhibition
flights in his little craft at the Crystal Palace, and so
successful were they that he determined to construct a much
larger craft.

The second Spencer air-ship, first launched in 1903, was nearly
100 feet long. There was one very important distinction between
this and other air-ships built at that time: the propeller was
placed in front of the craft, instead of at the rear, as is the
case in most air-ships. Thus the craft was pulled through the
air much after the manner of an aeroplane.