Note On A Pneumatic Method Of Measuring Variations Of The Acceleration Of Gravity (1920)(en)(4s)

VOL. 6, 1920 FPHYSICS: C. BARUS - , e, , ,, -,m - A -,,- 495 portion is to exceed the value for ordinary rockets, which is about 1/5. This action consists in the loading and firing of a number of charges successivelv in the same combustion chamber. The results of work upon this feature, to date, have been the development and experimental demonstration of a simple and light multiple charge apparatus, firing a few cartridges and travelling straight. In order to complete the development, it is necessary to adapt the apparatus to fire a large number of cartridges, and to make the parts, exclusive of propellant, sufficiently light. Work on increasing the number of cartridges is in progress. In order to complete the development with a minimum of expense, the perfecting of details should be carried out only insofar as is necessary in order to produce an inexpensive apparatus. The only expense of maintenance will be a new magazine for each ascent. In any case, the time required to reach the 10 km. level should be of the order of 20 seconds, if the retardation due to air resistance and gravity is minimized. As an illustration of what should be possible with an apparatus developed in this way, it may be said that, using as a basis for the estimate a velocity of ejection of 5,500 ft./sec., which is easily obtained, a rocket weighing of the order of 11 lbs. initially and 6 lbs. at the highest point would be needed in order to send instruments weighing one pound to the 10 km. level. NOTE ON A PNEUMATIC METHOD OF MEASURING VARIATIONS OF THE ACCELERATION OF GRAVITY' By CARL BARus DUPARTMINT OF PHYSICS, BROWN UNIVERSITY Communicated June 22, 1920 1. Introductory.-Some years ago I made an extended series of experiments2 on the diffusion of gases through water; the gas in this work was imprisoned in a cartesian diver, and the