PHILOSOPHICAL SOCIETY OF WASHINGTON. 33 



observed by Professor Hall with the five-inch equatorial, and by 

 Mr. 0. B. Wheeler with the three-inch equatorial. At the time 

 of contacts the sun was covered with a haze, but the sun and 

 planet were remarkably steady and well defined. The time of 

 the third contact was ol)served by Mr. Wheeler with a good deal 

 of uncertairty; and with the higher power used by Prof Hall, 

 the uncertainty was so great, on account of the faintness of the 

 objects, that he did not record any time. The last contact was 

 entirely lost on account of clouds. 



It had been found in the preliminary practice that the glass 

 mirror reflected so little light that, even on clear days, the time 

 of exposure had to be increased so much, in order to get dense 

 photographs, that these photographs were apt to be blurred and 

 of indistinct outline. It was decided, therefore, to make fainter 

 photographs with sharp edges. On the day of transit the haze 

 added very much to the difficulty of photographing, and it was 

 only when the haze lifted and the sun slione out brightly that 

 photographs could be made. Of these 13 are very good. 



Mr. HiLGARD followed with remarks on the measurement of 

 photographs of the sun, and expressed apprehension that the 

 want of sharply defined outlines would not allow of their being 

 measured with precision. 



83d Meeting. February 21, 18T5. 

 Vice-President Hilgard in the Chair. 

 Thirty-seven members and visitors present. 

 Mr. Hilgard read a paper — by Mr. M. C. Meigs 



ON THE MOVEMENTS CAUSED IN LARGE ICE-FIELDS BY EXPANSION 

 AND CONTRACTION, AS ILLUSTRATIVE OP THE FORMATION OF 

 ANTICLINAL AND SYNCLINAL AXES IN GEOLOGICAL FORMATIONS. 

 {This paper is published in Appendix VIL of this Bulletin.) 



Prof. C. A. Young, of Dartmouth College, by invitation, gave 

 an account of 



THE EXPEDITION TO PEKIN FOR OBSERVING THE LATE TRANSIT OP 



VENUS, 



nnder the direction of Prof. J. C. Watson. He stated that on 



