ASTRONOMY AND METEOROLOGY. . 327 



THE USE OF THE THERMOMETER TO DETERMINE THE PERIOD 

 OF SOLAR ROTATION. BY PLINY EARLE CHASE. 



Professor Henry's experiments on the temperature of the solar 

 disc showed that the spots are cooler than the brighter portions 

 of the photosphere, and the centre is warmer than the rim. These 

 evidences of difference in calorific power have been confirnKH.l by 

 subsequent observers, and Schwabe, Henshall, and Kirkwood, by 

 a study of sun-spots and the variations of solar magnetism, have 

 sought for indications of fixed points, or meridians, on the sun. 

 If the sun is a variable star, any permanent differences in super- 

 ficial structure, however masked by the irregular disturbances to 

 which the spots are usually attributed, may perhaps be accom- 

 panied by regularly recurring differences of temperature, which 

 should be manifested by the thermometer. 



The 7 years' hourly thermometric observations at St. ITelena 

 (1840-7) Avere examined in various ways, in order to discover any 

 traces they might furnish of cycles approximating to the supposed 

 period of solar rotation. After testing, by the method of least 

 squares, various assumed intervals between the limits of 25 and 

 2d days, the pointings were so decided and uniform, that all the 

 observations were arranged in accordance with a hypothetical 

 period of 27 1-14 days. The annual, semi-annual, and quarterly 

 groupings all confirmed the hypothesis that this was a normal 

 interval, and the belief was still further strengthened by various 

 comparisons with observations at Philadelphia, extending over a 

 period of 44 years (1825-69). 



If we then assume 27 1-14 days for the synoclical rotation of 

 the sun, the time of its sidereal rotation is about 25.085 days. 

 This is somewhat greater than the estimates of Sporer (24.6244) 

 and Carrington (24.9711), but nearly accordant with the more 

 recent estimate of Faye (25.07472.) ]Mr. Chase proposes to con- 

 tinue the investigation by a discussion of observations at other 

 stations. 



PLANETARY INFLUENCE ON RAINFALL AND TEMPERATURE. BY 



PLINY EARLE CHASE. 



The author has recently undertaken, for the Coast Survey, some 

 discussions of the meteorological influences of the moon. An ex- 

 amination of the records which have been kept at the Pennsyl- 

 vania Hospital, in Philadelphia, for forty-four years, confirmed 

 the conclusions of Loomis and othersthat cloudiness, rainfall, and 

 temperature, are each, to some degree, controlled by the lunar 

 phases. The " establishments," or local influences which modify 

 the results at different stations, often occasioning an entire oppo- 

 sition of curves, especially on oj^posite sides of large bodies of 

 water, were also clearly shown. There were marked evidences 

 of such establishments, due not only to position, but also to the 

 season of the year, occasioning contrasts between the summer and 



