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13.

[[underlined]] Table 1. [[/underlined]]

[[four column table]]

Type of Rocket | Efficiency | Mean Efficiency | Velocity corresponding to Mean Efficiency 
Common | 2.54% |  |  
"[[ditto for Common]] | 1.45  |  |  
"[[ditto for Common]] | 1.49  |  |
"[[ditto for Common]] | 1.95 | 1.86% | 957.6 ft/sec.
Coston ship | 1.75 |  | 
"[[ditto for Coston ship]] | 2.27 |  | 
"[[ditto for Coston ship]] | 2.62 | 2.21%  | 1029.25 ft/sec.

[[/end table]]

It will be seen from the above table that the efficiency of the ordinary rocket is close to 2 per cent; slightly less for the smaller, and slightly more for the larger, rockets; and also that the average velocity of the ejected gases is of the order of 1000 ft/sec. It was found by experiment that a Coston ship rocket, lightened to 510 grams by the removal of the red fire, had a range of a quarter of a mile, the highest point of the trajectory being slightly under 490 feet. A range as large as this is rather remarkable in view of the surprisingly small efficiency of this rocket.

[[underlined]] EXPERIMENTS IN AIR WITH SMALL STEEL CHAMBERS [[/underlined]].

An apparatus was next constructed, with a view to increasing the efficiency, embodying three radical changes; namely, the use of smokeless powder, of much higher heat value than the black powder employed in ordinary rockets; the use of a strong steel chamber, to permit employment of high pressures; and the use of a tapered nozzle, similar to a steam turnine nozzle, to make