98 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



riocl ; the greater cold in the interior of the land causes a 

 strong contraction of those strata of the air that lie nearest 

 to the earth's surface, whereby the atmospheric pressure is 

 increased. The increased pressure forces the air from the in- 

 terior, outward, toward the coast, causing the land winds. 

 The cold, dense air that streams outward from the continental 

 areas of barometric maxima seeks the valleys, on account of 

 its greater density, and over these it pours with a slight ve- 

 locity, as a river flows into the sea. The moisture that rises 

 from the warmer earth's surface is not dissolved by the cold 

 air, and forms fog in the valleys ; while the higher portions 

 of the country enjoy clear sunshine. Under these circum- 

 stances, the higher portions of the mountains enjoy a temper- 

 ature that is dependent upon the quantity of solar heat re- 

 ceived, while the valleys experience a cold air that is really 

 foreign to them, being brought to them by atmospheric cur- 

 rents from a great distance. These principles are very suc- 

 cessfully applied by Mohn to the explanation of a number of 

 observations, made at various altitudes, in the neighborhood 

 of Christiania; and the principle has long been familiar to 

 the American readers of the predictions of the Army Signal- 

 office. The latter institution has, we believe, never failed to 

 predict the cold northers of Texas and the Gulf States. 

 Jelinek. Zeitschrift 3Iet. y IX., 97. 



THE TEMPEKATUKE OF THE CLOUDS. 



The temperature of the clouds has been investigated by 

 Professor Poey, who has employed for this purpose the ther- 

 mo-electric pile. Professor Henry, secretary of the Smith- 

 sonian Institution, was, we believe, the first to apply this in- 

 strument to a similar object ; but the results obtained by 

 Professor Poey appear to be more positive and definite than 

 any that have been hitherto published. He has shown that 

 the cumulus and the cumulo-stratus of summer are the clouds 

 of highest temperature; then follows the fracto-cumulus, ex- 

 cept when it comes after the rain w r hich accompanies the 

 thunder-storm (in which case it is of a whitish color, very 

 rapid in its motion, much torn at its edges, and partaking of 

 the low temperature prevailing on such occasions). The cirro- 

 cumulus is colder than the cumulus, and the cirrus is the 

 coldest of all the clouds. It has during the last few years 



