356 
PROFESSOR J. H. POYNTING ON THE TRANSFER 
same potential as B at the junction. From this point to C, A will have lower 
potentials, and points with the same potentials will exist on B between C and the 
battery. Then either the level surfaces passing through C are closed surfaces, cutting 
A or B, and not passing through the battery at all, or, as seems much more probable, 
the surfaces from the battery which pass through C cut the circuit in three points in 
all outside the battery: once somewhere along A, once at C, and once somewhere 
along B. I have drawn and numbered the surfaces in the figure on this supposition. 
The heat developed in the parts of the circuit near C will thus be partly supplied 
Fig. 5. 
Fig. 6. 
from the junction C, where the current is against the E.M.I. The energy therefore 
moves out thence, giving a cooling effect. 
The Thomson effect may he considered in somewhat the same way. Let us suppose 
