The specific heat of pure copper and of some dilute copper + iron alloys showing a minimum in the electrical resistance at low temperatures

An ozone sonde eapable of measuring and transmitting the local ozone concentration has been developed for the I.G.Y. and is described in some detail. A continuous electrochemical detector measures the ozone concentration, providing a d.c. electric current of 0 to 5 $\mu A$ according to the amount of ozone in the air passed through it. This output current is telemetered by a current-controlled variable inductance which is interchangeable with a standard inductance coil in a Kew radiosonde. The element is of low cost, weighs about 600 g and requires very limited auxiliary equipment for its use. Sixty-five successful ascents have been made and the results of the European ascents are given.