"All around the earth on which we live is a comparatively thin layer of air known as the troposphere, which is usually of a thickness of about six miles, much like an atmospheric envelope enclosing the whole globe. Beyond that belt human beings cannot live, so that if scientists wish to ascend in the the stratosphere above they must have special means of providing themselves with the necessities of existence.
"Thus, in man’s insatiable desire for knowledge of conditions normally out of reach, stratosphere balloons have been constructed and it is believed that the stratosphere actually forms a belt 50 miles in thickness, with an upper stratosphere beyond it. The goal of such a balloon is made of an aluminium alloy and contains a camera, oxygen flask, radio receiver, and transmitter, and many recording instruments. The total weight of the gondola when loaded is about 15 cwts."
Source: "Newnes' Pictorial Knowledge", 1933
Artist: G. H. Davis