3 o8 POPULAR SCIENCE MONTHLY. 



containing the lens loaned by Professor Young pointing directly sky- 

 ward. 



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 each plate is about 4 feet; but it will be inferred 

 from the examples that the prominences and polar streamers as well as 

 their features, appear in imposing magnitude and detail. 



Many of what it is hoped will be the most interesting photographs 

 still await development, but Mr. Smillie's thorough preparation is prom- 

 ising adequate results. 



Heat op the Cokona. 

 Mr. Abbot, with aid of Mr. Mendenhall, appears to have meas- 



Tig. 3. North Polar Coronal Streamers. Taken with 15 inch Lens of 135 feet Focus. 

 Exposure 16 Seconds. 



ured the heat of the corona, and in spite of previous efforts, this is prob- 

 ably the first time that it has been really shown to exist. For five 

 minutes 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 shortly to appear. A diaphragm was interposed 

 in the beam having an aperture of only 0.4 sq. cm. 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 positive deflections had just been found, showing 

 that the corona was actually cooler than the background which had 

 been used at the room temperature. Next the black surface of the 



