17 



METEOROLOGY. 



CLEAR AND COLD NIGHTS AT TIME OF FULL MOON. 



Every one must have noticed that the atmosphere is less liable to be 

 obscured with clouds, and is more transparent during the nights about 

 the time of full moon than at other times. It is further a matter of com- 

 mon observation that at that period it is in general calm and cold. This 

 has no doubt led to the remark that the moon's ray is cold, and in this 

 distinguished from that of the sun. 



These facts belong to the common stock of knowledge possessed 

 by the coraraunity at large. Even the slightest observer knows that the 

 late frosts of Spring and the early of Autumn take place about the time 

 of new and full moon, but especially the latter, that the full moons of 

 Summer are accompanied with cool, serene nights, and that those of 

 Winter are in general marked by hard freezing weather. How much 

 surprise must not then the community have felt, when, during the early 

 part of last Summer, it was stated in numbers of the newspapers of the 

 country, upon the authority of Dr. Lardner, that the moon had no hijlu- 

 ence upon the weather. The statement was no doubt designed to have 

 reference to the prevailing opinion that it exerted a considerable influ- 

 ence in the production of rain. But the atmospheric changes from cloud 

 to clear, from rain to dry weather, are all bound up together in one phy- 

 sical series, so that if the moon be concerned in the production of the 

 one class it is also concerned in the production of the other. 



Facts so common, interesting and important as those just stated, 

 could not have been observed and known without having frequently 

 given rise to the question, "What is their cause, or how may they be 

 accounted for?" 



An explanation, not without a considerable degree of plausibilit)', 

 was oflered, at a recent meeting of "the British Association for the pro- 

 motion of Science," by Sir J. F. W. Herschell. Upon the authority of 

 the calculations of a French pliilosopher whose name cannot just now 

 be recalled, he stated that the temperature of the moon's surface result- 

 ing from its long exposure of two weeks during each lunation to the 

 rays of the sun rose to a point not less than that of boiling water. Ac- 

 cording to his opinion, that portion directly presented to us must attain 

 its maximum temperature at the time of full moon, and freely radiate its 

 heat to the earth. That heat being of the nature of non-luminous ca- 

 loric, which is more abundantly absorbed in passing through certain 

 media than luminous caloric is arrested by the vapor in the air in its 

 passage towards the earth, raising its temperature and rendering the so- 

 lution more perfect. In this manner, then, we are taught to believe, is 



