The paper describes a new system of meteorological sounding employing secondary-radar principles. Pressure, temperature and humidity are each telemetered to an accuracy of one-thousandth part of their operating range, although the elements at present used may not be capable of measuring the meteorological parameters to this degree of accuracy. In addition, wind speed and direction are automatically measured. The maximum slant range of the system is about 100 miles, and thus the height to which soundings and wind measurements can be made is, at present, largely limited by the height at which the balloon carrying the instruments bursts.