THE SUBDIVISION OF A CURRENT OF HOT GAS 91 descending channels q\ and #2 having equal temperatures t\ and fe, that one of these streams takes up the heat a little faster than the other and that, for example, ti becomes slightly less than fe- The column of gas q\ becomes, therefore, slightly heavier than the column #2, the current qi commences to flow with greater energy, and its velocity increases; .ti commences to become sensibly less than fe, the current q\ has a greater cooling effect than the current g2 which continues, on the contrary, to take up more heat; and, in the end, the entire stream of gases passes through the branch gi, while in the branch q2 there will be established at the same time a reverse current which circulates as indicated by the clotted arrows (Fig. 48). Q S-^ vb Q \ tf1 \ 72 I y 1 //• 1 '/ ^ x tl t<> s V V ;^; «"—» *"— Q FIG. 48. ^^;,,,. ,;,/^ FIG. 49. Therefore, a current of cold gases which are being heated cannot be subdivided equally between descending channels. When the subdivision of a stream of cold gases is made through ascending channels, the results will be as desired. Assuming that the currents flowing as indicated in Fig. 49 were not equal, q\>q% and, consequently, fe>£i- If fo>£i, the weight of the column <72 will be less than the weight of the column gi, the current #2 will become stronger; this will cause the temperature fe to become lower; at the same time t\ will increase in this manner and the two temperatures will be equalized; the two currents q\ and #2 will therefore be maintained equal. • It therefore follows that when a current of cold gas is to be heated it should be subdivided into a number of ascending streams.