MKTKoRnLOfiY- WATIK. 



117 



.1 r, rage sunshiru 



rds, Aas Agricultural College, 1891 1903. 



In percent 



Sun above Registered <>i' hours 



horizon. sunshine. Bun above 



horizon. 



Maximum. Mini in 1 1 ii 



January . 



February 



March 



April 



May 



June 



.Inly 



August 



Beptember 



October 



November 



December 



Total for yeai 



The results show that the months which are generally considered dark as regards 

 number of hours and 'lays of sunshine arc also 'lark in so far as they have the 

 smallesl percentage of theoretically possible sunshine. It is also apparent that the 

 largest monthly variations in the percentage of sunshine occur during the summer 



months. — F. w. woi.i.. 



On the distribution of photochemically active lig-ht on the northern hemi- 

 sphere at summer solstice, .1. Sebelien I Arch. Math. <»j Nalurvidensk., 26 | 1904), 

 No. 9, pp. 13). — The paper contains a discussion of previous work in this line by 

 Wieler, Langley, Spitaler, Bunsen, and Roscoe, with results obtained by the 

 author. 



By means of the formulas of the last two scientists mentioned, the amount of pho- 

 tochemically active light is calculate" 1 which falls on midsummer day on a horizontal 

 surface unit from sunrise to sunset for each tenth or fifth degree latitude. According 

 to die calculations of the author the maximum number of light degrees of direct sun- 

 Bhine, 89,060, falls at 30° latitude and the maximum degrees of diffused light, 39,839, 

 at the north pole, the total amount of lighi being highest at 30° latitude (114.^:;*> 

 At 82° latitude as much chemical light is received on the longest day of the year 

 through reflection from the sky as by direct insolation, viz, 39,000 light degrees. 



The results of the calculations are platted and discussed in detail in the paper. - 

 i. w. woi.i.. 



Photochemical studies of the ultraviolet part of sunlight, J. Sebelien | K. 

 SnrsL, Vidensk. Sehk. Skr., /, Math. Nat. KL, 1904, X<>. 9, pp. 59; Chem. Tig., ?8 

 {1904), No. 10/, />/). 1259-1268). — The paper is an exhaustive treatise on methods of 



measuring the intensity of the chemically active rays of sunlight, and of the author's 



researches on this subject. The latter were made mostly with Eder's reagent 



(ammonium oxalate and corrosive sublimate) during the year- 1898 and 1899. 

 The detailed results are given in the paper. 



The precipitates obtained were, "ii the whole, heaviest in summer and lightest in 

 winter, hut considerable daily variations occurred, viz, calculated on a 1 Bq. cm. 



surface, ir a few tenths of a milligram in December to several decigrams in June 



and July, the maximum precipitate ever obtained being 590.4 mg. (July 23, 1899). 

 The relations of the data obtained by tlie author to cloudiness, northern lights, sun 



spots, etc, are diseussed, and also the amount of photochemical light due to direct 

 radiation and to diffused light. 



The two kinds of light were found of equal intensity at an altitude of the sun of 



8©°, a result that closely corresponds to the determinations of Bunsen and l; 



"Sit/.her. K. Akad. Wis. [Vienna], 

 ''Ann. Phys., 108, pp. •-'•~>4. '_':.."». 



Math. Naturw. Kl., 2. Aht.. 80 L879 . 



