76 , BOARD OF AGRICULTURE. 



ing- temperature would kill." In the torrid desert of Africa, where 

 it has been said, "The soil is fire, and the wind is flame," the 

 refrigeration at night is painful to bear, so that ice is sometimes 

 formed there. Wherever the air is dry the daily rang'e of temper- 

 ature will be very great. A traveller in Spain relates, that in the 

 valley of Grenada, where the trees have all been destroyed, the 

 heat by day in the sun's rays was oppressive, while the hoar frost 

 was lying white in the shade. Allusions to the same law are found 

 in an ancient writing, where the Hebrew shepherd while tending 

 the flock of Laban, experienced great hardship through drought by 

 day and frosts by night, sleep departed from his eyes. The desert 

 and mountainous regions of our own country illustrate these phe- 

 nomena of radiation. In the mountain valleys along the Pacific 

 railroad, the thermometer may stand at 90° in the afternoon, and 

 at night fall below the freezing point. Near Salt Lake, Utah, it is 

 difficult to grow Indian corn, though the mean temperature is ten 

 degrees above that of Maine. The local cooling at night, and the 

 higher heats by day are both unfavorable to the crop. Men who 

 have been extensively engaged in making hay in the elevated val- 

 leys of California, assure us that they have had their filled water- 

 pail frozen over by night, so that by keeping it in the shade the 

 ice remained through the following day. These facts are impor- 

 tant as applicable in the future to human comfort. A close con- 

 nection exists between diminution of humidity and reduction of 

 temperature ; and the remedy, if any, is in protection from influ- 

 ences causing excessive dryness. A remedy applicable to wide 

 areas of northern territory where low temperatures occur unsea- 

 sonably, through the precipitate descent of cold air from the high 

 region of the atmosphere, may not be found ; but in the regions 

 where the extremes are not so great, where they just border on 

 the freezing temperature, they may be applied with much promise 

 of success. The principal cauge operating around and above us, 

 producing excessive dryness in the atmosphere and in the soil, is 

 the westerly wind, which alone is competent to reduce the amount 

 of vapor in the air, and to render it incapable of preventing the 

 escape of heat absolved by the earth during the day. 



On the Pacific coast the prevalence of westerly winds gives a 

 great uniformity to the temperature, and the most of the rain 

 comes from that quarter. These winds bear their moisture up the 

 slopes of the mountains, where it is condensed into clouds, and is 

 deposited as rain and snow ; so that as they pass eastward they 



