248 Intelligence and Miscellaneous Articles. 



deration. But it is consistent with my theory to attribute it also to 

 the fact that the existence of cloud and vapour is due to the sun and 

 the winds, and consequently the action of the moon, though con- 

 sistent, cannot be regular or constant. 



For example, if no clouds are formed at the j:eriod of new moon and 

 first quarter, the earth's radiant heat passes away into space, and the 

 result is cold at a time when curves of mean temperature for a 

 series of lunations, show heat ; and so in like manner, if more heat 

 than the moon is able to disperse occurs in the second half of the 

 lunation, where the curves indicate cold, the result, pro hac vice, 

 would be a higher temperature than the average. 



Lastly, as the moon's hemisphere turned towards the earth does 

 not, as it would appear, attain its maximum heat until the last 

 quarter (and it is probable also that it does not part with all its 

 radiant heat till several days after new moon), if any further expe- 

 riments are made with the thermo-electric pile, would it not be well 

 to try for heat at the third quarter, and that in a lunation in which 

 the moon takes the longest time in passing from the full, and so 

 receives the greatest amount of heat from exposure to the sun's rays ? 



Your faithful Servant, 



Ewhurst, February 14, 1865. J. Park Harrison. 



P.S. — The cloud-dispelling power of the moon has been observed 

 not only by Sir John Herschel, but by Baron Humboldt, M. Le 

 Verrier, the late Radcliffe observer (at Oxford), and Mr. Nasmyth ; 

 I am not aware if anyone but Sir John Herschel has attributed it to 

 the radiant heat of our satellite. 



ELECTRICAL STANDARD. 



To the Editors of the Philosophical Magazine and Journal. 



6 Duke Street, Adelphi, London, W.C., 

 Gentlemen, February 7, 1865. 



I have the honour to inform you that copies of the Standard of 

 Electrical Resistance chosen by the Committee on Electrical Stand- 

 ards appointed by the British Association in 1861, can now be pro- 

 cured by application to me as Secretary to the Committee. 

 A unit coil and box will be sent on the remittance of £2 10s. 

 The Standard is a close approximation to 10,000,000 —^ i n 

 Weber's absolute electromagnetic system, determined according to 

 new and^careful experiments made by different members of the Com- 

 mittee, and the copies are constructed of an alloy of platinum and 

 silver in a form chosen as well adapted for exact measurement. 



The want of a generally recognized standard of electrical resistance 

 has been universally felt, and led to the appointment of the Com- 

 mittee. They now desire me to express a hope that the motives 

 which have led to their present choice, and which are fully explained 

 in the several reports published by them, will induce you to assist in 

 procuring the general adoption of the new standard, 

 I remain, Gentlemen, 



Your obedient Servant, 

 (Signed) Fleeming Jenkin, 



Secretary to the Committee. 



