--•ME RECENT ASTB \L EVE" - 



pended by an extremely thin quartz fiber. All is i - i in a n. 

 . with a glass window the little ruin r, s si serve 



leflections of the vane- by the teles - . i a 



nd window of fluorite or other material ti - - tot ^ng 

 - rted "pj site i s to admit the i 



- red. The cas - -t _:.t and may be exhaust . I mv 

 I - le force which k- - vanes at " posit 



wht-n uninfluenced by radiation i- th- tori sticity of 1 



. and this - - ts t ration of tin - turns them t 



original position when turned temporarily from flu- 



ent- of radiation. 



An extraordinary degree of sensit : thi- instrument was 



indicated by experiments which were made on the heir 

 oated 2.000 feet from the concave mirror which focus s rays 

 the radiometer. The feeble radiation- of the candle at this g 

 - meed to turn the radiometer through nearly a hund: 

 divisions, and even the face of an observer, when placed in 

 before occupied by the candl< . - 25 s ivi- 



tenth of a single scale division could readily 

 it will be seen, to -peak figuratively, that with the ine 



might note the approach of a friend while - - stant, 



merely by the glow of his eountenan 



I • erecting the observation upon the candle for the absorpt - the 



earth's atmosphere in the layer between it and the ra 

 found that in the absence of the atmosphei - gle candle at up v. 

 of 16 miles could have been dete< " . = that the instrumental eq 

 ment was far more sensitive than that used by Profess - in the 



negatively resulting stellar observation- already alluded to. 



Experiment- were performed upon the ra I 5 of t - - _ 

 and Arcturus. and on the planets Jupiter and Saturn. The 

 of each of these objects was distinctly recognized, and caused, in 

 the mean, deflections of 0.51. 1.14. 2.38, and T s sions. 



respectively, when approximately reduced to zenith. 

 tive thermal effects of Vega. Arcturus. Jupiter, and Saturn are - 

 1:2.2:4.7:0.71. Thi-. it will be seen, i- quite appreciably different 

 from their relative brightness to the eye. a circumstance which r. 

 with additional experiments, lead to interesting conclus 

 the nature of the radiation received from these several 



4. THE OBSERVATIONS OF THE PLANET EB - 



The minor planet Eros, it will be recalled, was 3 Witt, 



the Urania Observatory at Berlin. August L3, S 6 



- nations it- approximate orbit was computed, this was 

 found to be so highly eccentric as to differentiate this new planet from 

 the many other asteroids with which it had been provisionally class 



