June 22, 1900.] 



SCIENCE. 



979 



Figure 4 is a view of a small part of 

 the great apparatus on the field, including 

 the terminus of the horizontal tube with 

 its canvas covering, which has been de- 

 scribed as like an extended ' A ' tent. The 

 photographic room is seen at the end of the 

 tube and bej'ond that the tube containing 

 the lens loaned by Professor Young, point- 

 ing directly skyward. 



That it will be impracticable to give here 

 all of the disc of the moon in the large 

 photographs, will be evident when it is 

 considered that the lunar circumference on 



been really shown to exist. For five min- 

 utes before second contact, the bolometer 

 was successfully exposed to the region of 

 the sky close to the narrowing crescent of 

 the sun where the corona was shortlj' to 

 appear. A diaphragm was interposed in 

 the beam having an aperture of only 0.4 

 sq. cm. and deflections rapidly diminishing 

 from 80 to 6 mm. were obtained, the last 

 being about 40 seconds before totality. 

 Then the diaphragm was opened to 290 

 sq. cm. and a negative deflection of 13 mm. 

 was observed after totality, where these 



Fig. 3. North polar coronal streamers. Taken with 15-inch lens of 135 feet fooas. Exposure 16 seconds. 



each plate is about 4 feet ; but it will be in- 

 ferred from the examples that the promi- 

 nences and polar streamers as well as their 

 features, appear in imposing magnitude 

 and detail. 



Many of what it is hoped will be most in- 

 teresting photographs still await develop- 

 ment, but Mr. Smillie's thorough prepara- 

 tion is promising adequate results. 



HEAT OF CORONA. 



Mr. Abbot, with the aid of Mr. Menden- 

 hall, appears to have measured the heat of 

 the corona, and in spite of previous efforts, 

 this is probably the first time that it has 



positive deflections had just been found, 

 showing that the corona was actuallj' cooler 

 than the background which had been used 

 at the room temperature. ISText the black 

 surface of the moon was allowed to radiate 

 upon the bolometer, and the still larger 

 negative deflection of IS mm. was ob- 

 served. 



The important result was that the corona 

 gave a positive indication of heat as com- 

 pared with the moon. 



This heat, though certain, was, however, 

 too slight to be subdivided by the disper- 

 sion of the prism, with the means at hand. 



The negatives taken to depict the outer 



