OF ARTS AND SCIENCES. 523 



culty was due in part to errors in the gears, and in part to the theo- 

 retically correct double Hooke's joint, which has now been replaced with 

 a belt and pulleys. 



"As may easily be imagined, the curvature of the spectral lines in 

 this spectroheliograph is very marked. If the first slit is straight the 

 second slit must be curved, to fit the K line, and the resulting image 

 of the sun is seriously distorted. By dividing the curvature equally 

 between the two slits, and moving the plate in a direction opposite to 

 that employed with a straight first slit, the distortion can be wholly 

 removed. You will notice that the images on the plate sent you are 

 round. 



" As soon as the eclipse work is over I hope to return to the spectro- 

 heliograph. The preliminary results are such as to lead me to expect 

 much from the instrument." 



PROFESSOR EDWIN H. HALL. 



Grant of April 26, 1895, $250, in aid of his investigation on the 

 thermal conductivity of metals. 



"I expect to read by title a paper at the next meeting of the Acad- 

 emy. I am using some of the money on a side research carried on by 

 Mr. McElfresh, a graduate student, on the thermo-electric effect of hy- 

 drogen occluded in nickel. Said effect seems thus far to be lacking." 



PROFESSOR FRANK A. LAWS. 



Grant of December 13, 1893, in aid of an investigation on the thermal 

 conductivity of metals. 



"In respect to the experiments on Thermal Conductivity I can say 

 that this constant for the cast-iron specimen has been determined, and 

 the result calculated. I have not published the method, for the cali- 

 bration is not satisfactory to me on account of a very peculiar set of 

 readings which I do not feel justified in rejecting. During the exam- 

 ination period I hope to straighten the matter out." 



PROFESSOR EDWARD L. NICHOLS. 



Grant of October 19. 1894, $250, in aid of investigations on the radia- 

 tions from carbon at different temperatures. 



" I bee to report that my investigation of the visible radiation from 

 carbon, made in part by the aid received from the Rumford Fund, is 

 nearing completion. Spectrophotometric comparisons of the lighl from 



