226 



SCIENCE. 



[N. S. Vol. XIX. No. 475. 



ical Observatory, consisting in measures of 

 the transparency of the air, the rate of receipt 

 of solar energy at the earth's surface, and 

 computations therefrom of the ' solar con- 

 stant ' of radiation and of the probable tem- 

 perature of the sun. 



The transparency of the air, measured at 

 many diiierent wave-lengths by the aid of the 

 spectro-bolometer, had appeared to vary great- 

 ly, so that the means for the first eight months 

 of 1903 fell below the means for 1901-2 by 

 amounts ranging from five per cent, in the 

 infra-red, to twenty per cent, in the blue. 

 During the latter four months of 1903 the 

 transparency had again risen, and approached 

 within two or three per cent, of its values for 

 the year before. 



Results were given of some twenty separate 

 determinations of the solar constant, but these 

 depended directly on the constants and theory 

 of the mercury pyrheliometer, so that they 

 may later be subject to amendment. In re- 

 sponse to questions Mr. Abbot described a 

 new form of pyrheliometer capable of exact 

 checks on its results, and now being tried 

 with most promising results at the Astro- 

 physical Observatory. 



A curve was shown giving the mean of five 

 days' determinations of the distribution of 

 solar radiation outside the atmosphere. From 

 this the position of maximum radiation ap- 

 peared at a wave-length of 0.49yu, correspond- 

 ing, according to Wien's law, to a solar tem- 

 perature of from 5800° to 5900°. 



Dr. Day remarked that the mean value of 

 the solar constant, as given by Mr. Abbot — 

 2.167 calories per cm." per minute — would 

 yield by Stefan's law a solar temperature of 

 5700° to 5800°. Ghaeles K Wead, 



Secretary. 



NEW YORK ACADEMY OP SCIENCES. 

 SECTION OP ASTRONOMY, PHYSICS AND CHEMISTRY. 



The regular meeting of the section was held 

 on January 4 at the American Museum of 

 Natural History. The officers of the section 

 for the year 1904, who were elected at the last 

 regular meeting of the section, are: 



Chairman — Professor Charles Lane Poor. 



Secretary — Mr. Cliarles C. Trowbridge. 



The first paper of the evening was read by 

 Professor Herschel C. Parker and was entitled 

 ' Altitude Observations with the Hypsometer 

 in the Canadian Eockies.' 



A brief outline of the various methods used 

 in altitude determinations was first presented, 

 showing that all are based on two general 

 methods, triangulation or measurement of 

 atmospheric pressure. In the latter method 

 the determinations are made either by means 

 of the several forms of barometer or by the 

 hypsometer. The difficulties attending the 

 use of all of the different forms of barometer 

 were pointed out and the advantages of porta- 

 bility and accuracy of the hypsometer shown. 

 Examples were then given illustrating the 

 extremely satisfactory results obtained with 

 the hypsometer during mountaineering ex- 

 peditions in the Canadian Eockies last sum- 

 mer. 



Professor Parker has had many years' ex- 

 perience in mountain work, making numerous 

 ' first ascents ' in British Columbia and 

 Alberta, and he gave as his conclusion that the 

 hypsometer is by far the most convenient and 

 accurate instrument for the determination of 

 altitudes under ordinary mountaineering con- 

 ditions. 



The second paper was read by Dr. George F. 

 Kunz and Professor Charles Baskerville on 

 ' Phosphorescence in Diamonds Produced by 

 Pitchblende.' They stated that a naturally 

 fractured piece of pitchblende (uraninite), 

 weighing 800 grams, from Pribram, Bohemia, 

 caused the 14i^- carat diamond (tiffanyite) * 

 to phosphoresce when laid upon it, or even 

 when a piece of window glass or a board three 

 fourths of an inch thick was interposed. The 

 diamond glowed, although more than one inch 

 of space intervened between it and the pitch- 

 blende. We have in this instance a substance 

 with a radio-activity of only 2 or 2| affecting 

 a radio-actively responsive substance, proving 

 that there exists a body of the latter character 

 in this ease that responds almost to the unit 

 one of radio-activity. The same specimen 

 of pitchblende did not affect a platinum- 

 barium cyanide screen. Another specimen of 

 pitchblende from Pribram, and others from 



* Science, December 18, 1903. 



