KEPORT OF THE SECRETARY. 



EPOCH 1900. 



107 



Unfortunately we can not either confirm or reject these possible planets by obtaining 

 additional evidence from the shorter-fcn ms plates, excepting possibly in one instance, 

 for near-by stars of about equal brightness are not shown on these other plates, so 

 that the absence of the suspects is only natural. However, the negative taken with 

 the 6-inch photographic telescope has a doubtful object precisely in the place of the 

 suspect at right ascension (1855) 4 hours, 8 minutes, 8 seconds, but this is so faint as 

 to be by no means a certain confirmation. It may be said with certainty that no 

 new objects as bright as fourth magnitude were in the field. 



It had been expected that other observers having similar apparatus would obtain 

 additional evidence, but this, so far as learned, was not the case, and future eclipses 

 must be awaited to settle the question of the possible intra-Mercurial planets. 



6. With the holometric apparatuH. — The heat of the inner corona was successfully 

 observed, and caused a deflection of 5 divisions as compared with the dark surface 

 of the moon, but its spectrum was too faint to observe with the bolometric apparatus. 

 Both the moon and the corona gave Jiff/afee deflections (18 and 13 divisions respec- 

 tively) as compared with screens at the temperature of the bolometer, while with 

 only one five-hundredth the aperture the sky where the inner corona was about to 

 appear gave positive deflections as compared with the screens, decreasing from 80 to 5 

 divisions during the five minutes preceding the totality. 



These observations indicate not only that the coronal radiation is very slight, but 

 that the cq/parent temperature of the inner corona is below 20° C. For it will be 

 noticed that the bolometer lost heat by radiation to the corona, as evidenced by a nega- 

 tive deflection. Hence, when we consider its visual photometric brightness at the 

 point where the bolometric measures were taken, which, judging from the results 

 obtained by several observers during the eclipses of 1870, 1878, and 1898, was at least 

 equal to that of the full moon, it is difficult to understand how the light of the 

 corona can l)e due largely to reflection of rays from the sun or even to the incandes- 

 cence of dust particles, for from sources of these kinds, which emit a great preponder- 

 ance of invisil)le infra-red rays, the bolometer would have given large positive 

 deflections. 



Thus during observations taken two days before the full moon of August, 1900, 

 with ajDparatus as nearly as possible identical with that used at Wadesboro, but 

 unfortunately with a very hazy and humid and even cloudy atmosphere, positive 

 deflections of 55 divisions were obtained from the moon as compared with a screen 

 at the temperature of the bolometer, and 86 divisions as compared with the dark 

 zenith sky.^ 



Observations on the daylight sky at a distance from the sun also resulted in large 

 positive deflections. 



^As appears in the Allegheny researches on the temperature of the moon, these 

 deflections would undoubtedly have been cfmsiderably increased had they been 

 made in a cl"ar and dry atmosi)h('n> at tlic liuu> of the full moon. 



