So far as I know, the only satisfactory determination of the position of the cobalt line on the thermoelectric diagram was made by Professor Tait's students in the Physical Laboratory of Edinburgh University some fifteen years ago. The position of the cobalt line, so found, was given along with the positions of certain alloys in a paper by Professor J. Gordon MacGregor and myself, published in the Transactions of the Royal Society of Edinburgh, vol. xxviii. (1878). The particular specimen of cobalt used in these early experiments was a short rod obtained by electrolytic decomposition. The noteworthy facts regarding its thermoelectric line were that it lay below nickel on the diagram, and that its inclination to the lead line was much greater than the inclinations of the iron and nickel lines.