Lunar Occultations for November, 399 



On the Editorial note at p. 211 of your Number for September, I 

 would observe, — 



That my reference was to the common definition of radiation, as the 

 rapid transmission of heat through bodies, without affecting their tem- 

 perature, and subject to reflection, &c, as light; whilst M. Becquerel 

 operated on wires soldered together, and thus, quoad the communica- 

 tion of heat, in at least virtual contact. 



Nor does § 2 1 7 of Sir J.F. W.Herschel's able discourse explain away, 

 to my comprehension, the apparent essential distinctions between ra- 

 diation and conduction, exemplified in the different order relating to 

 them assumed by different substances among the metals themselves, 

 and even amongst those the most similar in density and other quali- 

 ties; as is recognised in M. Becquerel's paper, in the tendency of a 

 variety of circumstances (as tarnishing a metallic surface, or covering 

 it with glass, &c.) to promote the one but impede the other ; in the 

 comparative tardiness of water and similar liquids to communicate heat 

 from particle to particle, though no evident obstruction to radiation 

 interferes ; as well as in many other well-known facts : radiation seem- 

 ing dependent only on the emitting substance and its contained heat ; 

 conduction on the receiving as well as the emitting substancef. 



Sept. 14, 1833. John Piudeaux. 



LUNAR OCCULTATIONS FOR NOVEMBER. 



Occultations qfjixed Stars by the Moon, visible at Greenwich in the 

 Year 1833. Computed by Thomas Maclear, Esq.; and circu- 

 lated by the Astronomical Society. 



f This last remark of Mr. Prideaux respecting conduction is illustrated, 

 perhaps, by the phenomena of vibrating metals : see Prof. Forbes's obser- 

 vations, in our last Number, p. 304. — Edit. 



