Intelligence and Miscellaneous Articles. 247 



timent that unless very distinctly disavowed in all future cases, the 

 interests of the Royal Society and of science will suffer materially. 

 " I remain, dear Sir, very sincerely yours, 



(Signed) " J. F. W. Herschel." 



" Davies Gilbert, Esq., V.P.R.S.,45 Bridge Street, Westminster." 



It can hardly be necessary for me to recall to Dr. Davy's recollec- 

 tion that I have nowhere asserted that the President had promised 

 the Secretaryship to Mr. Babbage, or either directly or by implica- 

 tion promised to appoint him to, or to give him, that office. 

 I have the honour to be, Gentlemen, 



Your obedient Servant, 

 J. F. W. Herschel. 



LUNAR INFLUENCE OVER TEMPERATURE. 



To the Editors of the Philosophical Magazine and Journal. 

 Gentlemen, 



With great deference and respect for Dr. Buys Ballot, I cannot 

 but express a very strong conviction that the value of results derived 

 from a tabulation of mean temperatures of the different days of the 

 moon's age for the last seventy-five years (from 1789 to 1865) far 

 outweighs any that attaches to the sixty years previous. 



In an inquiry into lunar influence over 'temperature, the most de- 

 licate and accurate instruments are essential in order to detect effects 

 which may often require to be measured by tenths and hundredths 

 of a degree (Fahr.). No thermometer, however, of great accuracy 

 existed between 1723 and 1789 ; and even if any had been available, 

 it would seem extremely doubtful whether observations 130 years 

 ago were made with sufficient regularity and care, or at the exact 

 hours requisite to obtain true mean results. In Dr. Buys Ballot's 

 work, Les changements periodiques de temperature, p. 22, there is a 

 passage which of itself would suggest a doubt on this point. 



It is remarkable, too, that the existence of cold after full moon 

 first becomes apparent in the sums of temperature at Harlem shortly 

 after the date of the invention of Six's self-registering spirit-ther- 

 mometer. 



My results (which also show cold in the second half of the luna- 

 tion) completely accord with conclusions arrived at by Bouvard, 

 Schubler, Flaugergues, and other physicists, who have sought for 

 lunar influence over rain, cloud, the serenity of the sky, &c. I 

 have consequently from the first attributed the occurrence of heat 

 and cold in the lunation to the presence or absence of cloud as a 

 known cause of the phenomenon. There is indeed no meteorolo- 

 gical fact more certain than that the greatest cold occurs under a 

 clear sky, whether in the polar regions or the desert of Sahara, and 

 that heat is retained in the ground and lower strata of the air by 

 the agency of cloud*. 



As regards the want of perfect regularity in the action of the 

 moon, Dr. Buys Ballot's suggestion that it may be due to her influ- 

 ence being partly direct and partly indirect, is worth careful consi- 

 * As shown by Glaisher, in the Phil. Trans. 



