THE TEMPERATURE OF THE MOON.—In a paper appearing. in the Astrophysical Journal (No. 5, vol. xxiv.), Mr. F. W. Very discusses Mr. Coblentz's recently-publishd conclusion that, from an investigation dealing with the reflection of heat radiations from various mineral substances, it may be deduced that the apparent temperature of the lunar surface is chiefly due to reflected solar radiations, and that the actual temperature may be about—225° C., in accordance with Langley's first conclusion. Mr. Very points out that his investigations of the radiations show that the larger part of them are not merely specularly reflected, but are radiated, the moon having first absorbed the heat from the solar radiations. Instead of 225° C., he suggests that the temperature of the lunar body may reach a maximum of about 100° C., the corrected lunar-radiation curve being similar to that appertaining to bodies not much below the temperature of boiling water.