This able reasoner and aeronaut pointed out that the contrivance about to be tested aimed at obviating two principal drawbacks which the parachute had up to that time presented, namely (1) the length of time which elapses before it becomes sufficiently expanded, and (2) the oscillatory movement which accompanies the descent. In this new endeavour the inventor caused his machine to be fixed rigidly open, and to assume the shape of an inverted cone. In other words, instead of its being like an umbrella opened, it rather resembled an umbrella blown inside out. Taking, then, the shape and dimensions of Mr. Cocking's structure as a basis for mathematical calculation, as also its weight, which for required strength he put at 500 lbs. Mr. Monck Mason estimated that the adventurer and his machine must attain in falling a velocity of some twelve miles an hour. In fact, his positive prediction was that one of two events must inevitably take place. "Either the parachute would come to the ground with a force incompatible with the safety of the individual, or should it be attempted to make it sufficiently light to resist this conclusion, it must give way beneath the forces which will develop in the descent."