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ii.

from the average velocity of ejection, which was obtained indirectly by observations on the [[underline]] recoil [[/underline]] of the rocket.

It was found that not only does the powder in an ordinary rocket constitute but a small fraction of the total mass (1/4 or 1/5), but that, furthermore, the efficiency is only 2 per cent; the average velocity of ejection being about 1000 ft/sec, (Table I, page 13). This was true even in the case of the Coston ship rocket, which was found to have a range of a quarter of a mile.

Experiments were next performed with the object of increasing the average velocity of ejection of the gases. Charges of dense smokeless powder were fired in strong steel chambers (Fig. 6, page 14); these chambers being provided with smooth tapered nozzles, the object of which was to obtain the work of expansion of the gases, much as is done in the De Laval steam turbine. The efficiencies and velocities obtained in this way were remarkably high (Table II, page 16); the highest efficiency, or rather "duty", being over 64 per cent, and the highest average velocity of ejection being slightly under 8,000 ft/sec, which exceeds any velocity hitherto attained by matter in appreciable amounts.

These velocities were proved to be real velocities, and not merely effects due to reaction against the air, by firing the same steel chambers [[underline]] in vacuo [[/underline]], and observing the recoil. The velocities obtained in this way were not much different from those obtained in air (Table III, page 34).

It will be evident that a heavy steel chamber, such as was used in the above mentioned experiments, could not compete with the ordinary rocket, even with the high velocities which were