118 ANNUAL RECOllD OF SCIENCE AND INDUSTRY. 



and Bache. Schreiber's observations were made in three 

 places at the same altitude, two within houses and the third 

 in the open air. In calm weather the pressure at all tliree 

 places was the same. As soon, however, as the wind blew 

 even with moderate force the pressure within the house was 

 always lower than in the open air. It was also noticed that 

 in the house the pressure oscillated with the strength of the 

 wind, and every gust of wind was accompanied with a cor- 

 responding fall in the barometer ; while in the open air the 

 barometer remained quiet. The barometric depression Avith- 

 in the house was quite considerable, amounting to one quar- 

 ter of a millimeter for a velocity of six meters per second, 

 and 1.15 millimeters for a velocity of 18 meters per second. 

 bth Bericht Naturw. Gesellschaft^ Chemnitz, 1875, 17-22, 

 26-36. 



A NEW FOEM OF HYGEOMETEK. 



Among the new forms of the hygrometer, are noted those 

 as made by Lambrecht according to the plan and under the 

 supervision of the inventor, Klinkerfues, of Gottingen. The 

 method of construction of this instrument is not made pub- 

 lic, but it is stated that it is always compared with the 

 psychrometer, and that in every respect it is exceedingly 

 trustworthy. GieheVs Zeitschrift ges. Natiirw., 1875, XII., 

 300. 



THE FOEMATION OF SXOW AS OBSEEVED FEOM BALLOONS. 



In a balloon ascension on the 29t]i of November, 1875, 

 Tissandier observed that the fall of small crystals of snow 

 which prevailed at the earth's surface ceased after reaching: 

 a moderate altitude. At 700 meters above the earth's sur- 

 face the temperature was 2 Centigrade. At this altitude 

 a thick cloud spread over the earth's surface, having a ver- 

 tical depth of 800 meters. Within this cloud the tempei'a- 

 ture sank to 4 Centigrade. At 1500 feet above the upper 

 surface of the cloud was found a stratum of ice crystals to 

 the depth of 150 meters. Above this the temperature of 

 the air was 0. The snow crystals had a very remarkable 

 appearance ; and the rise in temperature at this altitude de- 

 pended undoubtedly upon the formation of the crystals and 

 the evolution of latent heat. 19 C, 1876, 66. 



