Proof of a Theorem Due to Heaviside.

in 1914, showing a decidedly lower transmission of radiation through the water cell, in the case of Venus and Saturn. The intensity of the planetary radiation increases with decrease in the density of the surrounding atmosphere and (as interpreted from the water cell transmissions) in per cent of the total radiation emitted, is as follows: Jupiter (0), Venus (5), Saturn (15), Mars (30) and the Moon (80). The water cell transmission of the radiations from the southern (50.6%) and northern (53.1%) hemispheres of Mars should be and is higher than that of the radiations emanating from the equatorial (47.3%) region, owing to the depletion of the reradiated energy by the greater air mass. Moreover, the intensity of the planetary radiation from the northern hemisphere of Mars was found to be less than from the southern hemisphere. This is to be expected in view of the observed cloudiness over the -northern hemisphere which is usually the brighter and is approaching the winter season, and hence is at a lower superficial temperature. These data were obtained through the generosity of the Lowell Observatory, Flagstaff, Arizona, who financed this research. Dr. C. 0. Lampland again kindly operated the telescope and it is intended to publish the complete results in a joint paper on the measurements of planetary radiation and their astronomical significance. As already stated, the object of the present note is primarily to place on record a verification of the results, obtained a year ago, on stellar temperatures.