The following are a modification of some experiments conducted in the summer of 1871, and communicated to the Society on the 15th of January 1872. These consisted in heating a magnet uniformly throughout, and then noting the change in magnetic strength. Those conducted this winter consisted in heating one pole of a magnet, while the other was kept at a temperature as nearly constant as possible, and then noting the change of magnetic strength in both poles. The arrangement adopted was the same in both series of experiments, only being double in the latter. It consisted in having a magnet set magnetically east and west, each end of which passed through a cork fitted into a hole made in the side of a copper pot, one of which was filled with oil and heated by means of a brass Bunsen, while the other was filled with water at the temperature of the air of the room. The temperatures of both ends of the magnet could thus be ascertained by means of mercurial thermometers.