PROCEEDINGS OF THE REGENTS. 131 
British Columbia expedition.—The Secretary briefly reviewed his 
field work and studies in Cambrian geology during the summer of 
1913. 
Solar radiation expedition—Mr. C. G. Abbot, Director of the 
Astrophysical Observatory of the Institution, spent several months 
in California during the summer and fall of 1913, in continuation of 
studies on the variation of the solar constant. The special work 
of the year was in connection with the variability of the brightness 
of different parts of the sun. A tower telescope was constructed on 
Mount Whitney (14,500 feet) and numerous observations made, 
which it is hoped will furnish an independent check on the varia- 
tions to which the sun now appears to be subject. As a further test 
of the results obtained and to overcome any objections that might 
be made in scientific circles as to their soundness, Mr. Abbot devised 
a special self-recording pyrheliometer which may be attached to a 
sounding balloon and sent up entirely free from any connection with 
the earth to the greatest height to which balloons may penetrate the 
atmosphere. Five such instruments were constructed at the Astro- 
physical Observatory in 1913, and, with the cooperation of the 
United States Weather Bureau, they were sent up by observers of 
that bureau from Catalina Island, Cal., about the end of July. All 
were recovered, and although the apparatus had been untried up to 
that time, three of the instruments gave valuable records, taken at 
altitudes as great as 50,000 feet. These observations have not yet 
been definitely reduced, but the preliminary results indicate that 
just such values were found as will confirm in a very satisfactory 
manner the conclusions already reached. Some of the balloons as- 
cended over 100,000 feet (19 miles), but owing to the intense cold 
no records were made, the mercury in the Smithsonian pyrheliome- 
ters having frozen. The lowest temperature recorded by the instru- 
ments of the Weather Bureau was 76° F. below zero, which is far 
lower than the freezing point of mercury. It is expected to renew 
the experiments next spring, when measures will be taken to prevent 
the freezing of the mercury, and it is hoped then to obtain tempera- 
ture records at altitudes of 100,000 feet or more. 
Biological work in North China.—At the annual meeting on De- 
cember 12, 1912, the board was informed that Mr. A. de C. Sowerby 
was making collections in North China for the National Museum, 
through the liberality of a gentleman who desired that his identity 
be not disclosed. The same condition prevails now. 
Mr. Sowerby has recently notified the Institution of the shipment, 
principally from Manchuria, of 121 specimens, including squirrels, 
hog deer, moles, voles (a species of mouse), rats, chipmunks, shrews, 
hedgehogs, weasels, and badgers, many of which are thought to 
be new species. He will continue his expedition in North and West 
Shansi and in the Hei-lung-chang region of Manchuria. 
