532 Scientific Intelligence. 



stated, they show a considerable variation in the radiation from the 

 sun from time to time, sufficient to produce a very appreciable effect 

 upon the temperature of the earth. The probable mean value of 

 the solar constant obtained is estimated in round numbers at 2'1 

 calories per square centimeter per minute ; otherwise expressed, 

 this implies an intensity of solar radiation which would melt an 

 ice shell over the earth's surface 35 meters (114 feet) in thickness 

 annually. Substantially similar results are obtained for observa- 

 tions at sea level, and at altitudes of 1800 (Mt. Wilson) and of 

 3500 meters (Mt. Whitney). The variations of the solar radiation, 

 as observed at Mount Wilson, are comprised between 1*93 and 

 2*14 calories, and at Washington 1*89 to 2 - 22. The variation of 

 intensity of about 3-J per cent between August and October, due to 

 change in the distance of the sun, is distinctly noted in the Mount 

 Wilson observations, which indicate that the larger changes noted 

 are in fact solar, and not atmospheric or accidental. In consequence 

 of the interference of clouds and water vapor, it is shown that 

 the earth can radiate only slightly into space, the temperature 

 being kept nearly constant, chiefly by the layer of water vapor 

 at a height of 4000 to 5000 meters. This layer is estimated as 

 being 10° or more below 0° C. It is shown to be probable that 

 the changes in solar radiation produce not infrequently marked 

 changes in temperature over the continents, and. such changes 

 could be predicted if accurate measurements of the solar radiation 

 were continued at a few well-selected situations. It is further 

 indicated by comparative measurements of the center and the 

 edge of the solar disk, that observed changes in total radiation 

 accompany a variation in the transparency of the solar envel- 

 ope and perhaps are caused by it. Numerous other points are, 

 brought out in detail through the body of the work, which also 

 gives the observations in full and the methods and instruments 

 by which they have been obtained. 



4. Bulletin of the Mount Weather Observatory • prepared 

 under the direction of Willis L. Moore, Chief U. S. Weather 

 Bureau. Vol. i, pt. 2, pp. 65-133, charts vii-ix. — Among the papers 

 contained in this second number of the Bulletin of the Mount 

 Weather Observatory may be mentioned one by W. R. Blair, 

 on the change of phase in electrical waves on passing through 

 thin plates and the refractive index of water for such waves ; 

 also by the same author, on upper air temperature in October, 

 November and December, obtained by kite flights at a mean 

 altitude of 2342 meters, and a maximum of 7044 meters. The 

 results are shown graphically on three charts which are highly 

 interesting. Still another article by H. H. Kimball discusses 

 observations with the pyrheliometer and polarimeter. 



5. Field Columbian Museum. — Recent publications are the 

 following : 



Annual Report of the Director, Dr. Frederick J. V. Skiff, to 

 the Board of Trustees for 1907. Pp. 109-212, plates xviii-xxxii. 

 Geological Series, Vol. II, Table of Contents and Index. 



