LS78-] 1UJ [Barker- 



ance of the shunt perhaps to one-fiftieth of an ohm. The spot of light was 

 generally deflected nearly off of the scale. The light was again brought 

 to zero by varying the resistance of the tasimeter, and another one-half 

 inch of wire included in the shunt, another deflection and another balance 

 was obtained by the tasimeter. Thus by gradually increasing the delicacy 

 of the galvanometer by increasing the resistance of the shunt and balancing 

 at every increase, the whole of the current was allowed to pass through 

 the galvanometer and the shunt taken off. When this point was reached 

 the clamping magnet or director was in close proximity to the case of the 

 galvanometer. To increase its delicacy to the fullest extent it became 

 necessary to raise the director to the top of the rod. This was done by 

 raising it cautiously a quarter of an inch at a time, bringing the spot of 

 light to zero each time by the tasimeter. 



"In order to form some idea of the delicacy of the apparatus when thus 

 adjusted, a preliminary experiment was made on the evening of the 27th, 

 Avith the star Arcturus. The tasimeter being attached to the telescope, the 

 image of the star was brought on the vulcanized rubber. The spot of 

 light from the galvanometer moved to the side of heat. After some minor 

 adjustments, five uniform and successive deflections were obtained with 

 the instrument, as the light of the star was allowed to fall on the vulcanite 

 to produce the deflection, or was screened off to allow of a return to zero. 



" It was in this condition when the eclipse occurred. The tasimeter 

 was placed in a double tin case, with water at the temperature of the air 

 between the walls. This case was secured to a Dollond telescope of four 

 inches aperture. No eye piece was used. At the moment of totality the 

 spot of light was slowly passing towards cold. When I withdrew a tin 

 screen and allowed the edge of the luminous corona to fall upon the rubber, 

 the spot of light stopped, went gradually off of the scale towards heat, its 

 velocity accelerating as it approached the end. The time required for the 

 light to leave the scale was from four to five seconds. 



"I interposed the screen and endeavored to bring the light back to zero, 

 but I was unsuccessful. Had I known that the heat was so great I should 

 have used a platinum strip in place of the vulcanite, and decreased the deli- 

 cacy of the galvanometer by the approach of the damping magnet. 



" I would then doubtless have succeeded in getting two or more read- 

 ings, and afterwards by comparison with bodies of known temperature 

 would have obtained a near approach to the temperature of the sun's 



corona.'' 



Telespeotkoscopic Observations. 



My own results, obtained with an analyzing spectroscope attached to the 

 telescope, seem to be almost unique in this eclipse. This fact must be my 

 apology, if any be needed, for introducing here at such length, the facts of 

 the case as contained in my report. 



The instruments and apparatus used in the observations were loaned for 

 the purpose from the physical cabinet of the University of Pennsylvania. 

 They consisted (1) of an equatorially mounted achromatic telescopr of 

 four inches aperture made hj Jones of London ; (2) a direct vision astronom- 



