xxxvi GENERAL SUMMARY OF SCIENTIFIC AND 



ordinary thermometer screen, -without ventilation, gives the temper- 

 ature of the air accurate to one twentieth of a degree Centigrade. 



Theorell invented, for the use of tlie Swedisli Arctic Expedition, 

 an anemometer which maintained a continuous register for the di- 

 rection and velocity of the wind, notwithstanding the intense cold 

 to which it was exposed. A full description of it has been recently 

 published in Wijkander's Memoir, in the 12th volume of the Swed- 

 ish Academy. 



The study of solar radiation by the apj^aratus invented by Viole 

 has been prosecuted by him by means of observations made on Mont 

 Blanc, and at lower stations. He concludes the temperature of the 

 solar surface to be about 1500 Centigrade. 



Dr. Robinson, of Armagh, has made an important contribution to 

 anemometry by the publication of a new analytical theory of his well- 

 known anemometer. 



Du Claux shows that mixtures in definite iDrojDortions of crystal- 

 lizable salts in water deposit their crystals at very definite temj^era- 

 tures, and may therefore be used, in some cases, as thermometers. 



Jannsen has, by means of temporary apparatus at Montmartre, 

 been taking daily photographs of the sun. He records that during 

 the cold spell in France, the first part of May, there were no solar 

 sj)ots visible a fact quite in accordance with other investigations, 

 according to which, in high latitudes, the coldest seasons occur when 

 few sjDots prevail on the sun. 



Professor Houston, of the Philadelphia High School, states that he 

 is at work on a proposed improvement of the barometer, in which 

 he hopes, by means of a scale floating on the surface of the mercury, 

 to read with greater ease and precision the atmospheric pressure. 



Dr. Hellmann, in his discussion of wind observations, suggests that 

 we need instruments which shall measure both the vertical and the 

 horizontal components of the motion of the wind. 



C. Investigations and Results. 



Professor Loomis has continued his contributions to American me- 

 teorology, which have been uniformly published in the American 

 Journal of Science after having been first presented to the National 

 Academy of Sciences. 



In his fifth paper he gives a collection of data relating to hurri- 

 canes, and deduces for American storms a connection between rain- 

 fall and the progress of storms. 



Maquenne has made an important determination of the power of 

 leaves to absorb and radiate heat. His experiments, of course, were 

 conducted at temperatures not exceeding 120 ; and the radiative 

 powers averaged from 91 to 97 ; while the absorptive powers va- 

 ried from 94 to 97, lampblack being adopted as the standard of 

 comparison. 



