and a Sinclair paint solvent. The ballast valve or dribbler essentially perform the same function as the Japanese altitude control on the balloon bombs yet it is simpler and permits use of a liquid ballast for better control.
Another piece of equipment that is under construction by Kollsman Instrument Company is a motor-switched radiosonde modulator. It presents pressure data to the radiosonde transmitter as a variable resistance. The meteorological data is programmed by a samll Brailsford Electric motor. This modulator will provide the contact that seals off the diaphragm in the ballast valve. A complete discussion of this equipment will be furnished upon its delivery.
Sketches of balloon and rigging of the balloon to be used on to the main problem are given in the appendix and are self-explanatory.
Computations
A chart showing the relation between altitude, gross lift, and balloon size has been found necessary.
Data for it was computed using mean aerological soundings as reported in the Monthly Weather review for 1943.
A chemical term, molar volume (in cubic feet) was used as a term relating the sounding data with buoyancies of the balloons at various altitudes.
Using the simple gas laws, the molar volume of dry air was computed thus:
I. (1) Molar volume of any gas at standard conditions is 359 ft. $ ^{3} $
(2) From Monthly Weather Review Jan. 1943, the mean sounding data at 15 km for Lakehurst, N. J. is: Temperature $ - 5 9. 5^{\circ} \mathrm{C} $
Pressure 120 mb.