176 



Sun, 3°. Spot, 4°i. 



Spot, l°f. Sun, 5°. 



Spot, 2°. Sun, 4°i. 



Sun, 3°. Spot, 3°f . 



Sun, 2°i. Sun, 2°. 



Spot, 2°. Spot, 3°i.* 



Spot, 2°. Spot, 0°|. 



Sun, 2°i. Sun, 2°^. 



Spot, 4°f. Sun, 1°A. 



Sun, 5°. Spot, 0°. 



The change in the temperature during the intervals of observation, 

 is due to the variations in the temperature of the room differently af- 

 fecting the two extremities of the pile. 



In consequence of cloudy weather, another set of observations were 

 not obtained until the 10th of January, and at this time the spot had 

 very much changed its appearance; the penumbra, while it retained 

 its dimensions in one direction, was much narrowed in the other, and 

 the dark part was separated into two small ones ; also the sky was 

 not perfectly clear, and therefore the results were not as satisfactory 

 as those of the previous observations ; the indications were, however, 

 the same as in the other sets, exhibiting a less degree of heat from 

 the spots. 



Cloudy weather prevented other observations on the heat of dif- 

 ferent parts of the sun, particularly a comparison between the tempe- 

 rature of the centre and the circumference of the disc, which would 

 have an important bearing on the question of an aimOophei* of the 

 sun. The observations will be continued, and any results of interest 

 which may be obtained, will be communicated to the Society. 



Professor Henry also gave an account of some observations 

 he had made on capillarity, in addition to those he had before 

 communicated to the Society on the same subject. 



In 1839, he presented the results of some experiments on the per- 

 meability of lead to mercury; and subsequent observation had led 

 him to believe that the same property was possessed by other metals 

 in reference to each other. His first attempt to verify this conjecture 



* At tliis observation a slight cloud probably passed over the sun's disc. 



