304 Scientific Intelligence. 



tion made at various altitudes from sea level up to the highest practicable 

 mountain peak (Mount Whitney), thence in a balloon as high as man could 

 live, thence to a height of 15 miles, and concludes that the solar constant of 

 radiation is l - 93 calories per square centimeter per minute. Dr. Abbot dis- 

 cusses also the interesting fact that considerable fluctuations of the " solar- 

 constant " values occur from day to day ranging over nearly 10 per cent 

 between the extreme limits, 1 - 81 and 1"99 calories. In 1913 the radiation 

 of the sun was 2 '5 per cent below the mean, and 1 per cent above the mean 

 in 1914. A high average value is said to be indicated for 1915. Dr. Abbot 

 remarks in conclusion : " Short-period fluctuations of solar radiation were 

 large in 1913, but small in 1914. Associated with these quick, irregular 

 fluctuations are found variations of contrast of brightness between the center 

 and edges of the solar disk. Curiously enough, while greater contrast is 

 associated with greater solar radiation and with numerous sun spots in the 

 general march of the sun's activity, lesser contrast is associated with greater 

 solar radiation in the march of the quick, irregular fluctuations of the sun's 

 emission. This paradox points to two causes of solar variation- — the long- 

 period changes may probably be caused by changes of the sun's effective 

 temperature attending the march of solar activity ; the quick fluctuations 

 may be ascribed to changes of the transparency of the outer solar envelopes." 



2. Memorial Volume of the Transcontinental Excursion of 

 1912 of 'the American Geographical Society of New York, Pp. 

 xi, 407 ; with numerous plates, maps and other illustrations. New 

 York, 1915 (Published by the Society). — This handsome volume 

 forms a fitting record of the remarkable double trip across the 

 United States accomplished in 1912 by the International Geog- 

 raphers under the auspices of the American Geographical Societ} 7 ". 

 The general idea for this excursion first originated with Pro- 

 fessor Davis in 1908, and was later developed by him ; in the 

 leading paper of the volume (pp. 2-7) he gives an account of the 

 growth of the plan from the beginning and the way in which it 

 was carried out under his able supervision, as director. The his- 

 tory of the trip is given by Professor Albert P. Brigham 

 (pp. 9-45). The important occasion of the excursion was the 

 celebration of the sixtieth anniversary of the founding of the 

 American Geographical Society of New York and the completion 

 of its new building on upper Broadway. Forty-three European 

 geographers from thirteen different countries were present, and 

 with their American associates carried on a journey beginning on 

 August 22 and extending over two months to the Pacific coast 

 and back. The important object aimed at was to give each per- 

 son present as good an opportunity as possible to become 

 acquainted with the most interesting features of the United 

 States, and the itinerary given by Dr. Brigham, with the special 

 notes and maps accompanying it, show how thoroughly the plan 

 was carried out. Portraits of many of the delegates accompany 

 this paper by Dr. Brigham. The remainder of the volume, up- 

 wards of 300 pages, is occupied by a series of twenty-four inter- 

 esting papers by the foreign delegates, nearly all of which are 

 published here for the first time. These papers are in part in 

 French and German and contain valuable contributions to the 

 geography of the regions visited as seen through foreign eyes. 

 They are liberally illustrated and some of the most interesting 



