STATK AGRICULTURAL SOCIETY. 291 



DEPOSITION OF DEW. 



During the Winter months dew falls in the ordinary way. and hence 

 needs no special notice: but in the Summer months, when the whole coun- 

 try is arid, and there is no water to evaporate, the copious dews are brought 

 entirely by the westerly winds from the sea. If no westerly breeze, or but 

 a slight one springs up towards evening, there is no dew. The heavy dews 

 of Summer, which modify the climate so remarkably, differ from ordinary 

 dew in the manner of their deposition, being in great part precipitated in 

 the air in the form of mist before being deposited on the earth. On Summer 

 evenings a few clouds are commonly to be seen in the western horizon soon 

 after sunset. Later in the evening they increase in number, become lower 

 and looser, and sweep past at no great elevation, and often with considera- 

 ble velocity. Towards midnight, or later, they become still more abundant 

 and still lower, brushing the tops of the hills as they pass, and depositing 

 much of their moisture upon them, although dew may fall, even in Sum- 

 mer, in the usual way on clear nights; the surest sign of a copious deposi- 

 tion is the appearance of clouds with a westerly wind after sunset. Dew is 

 most copious in the Spring, and in September and October, except during 

 sirocco weather, when there is none. 



Clouds and a westerly wind at sunset and afterwards, are not, however, 

 always indications of a very damp night. It is the continuation of the west- 

 erly wind during the night that brings abundance of dew. Often at day- 

 break the sky is obscured by a heavy mist, and the ground is wet as if rain 

 had fallen. When the sun begins to act upon this mist, large masses of 

 white clouds are formed, which, however, soon disappear before the great 

 heat, leaving overhead only the usual blue sky of Summer. 



UNHEALTHY PERIOD OF THE YEAR. 



The unhealthy period of the year, the period in which the climatic dis- 

 eases of the country, such as ophthalmia, fevers, and dysentery, are most 

 prevalent, extends from May to October, inclusive. Six things strongly 

 characterize this period: (1) almost entire absence of rain; (2) low atmos- 

 pheric pressure, with small range; (3) high temperature, with great daily 

 range; (4) great dryness of the atmosphere; (5) a very small amount of 

 cloud; and (6) except at the beginning and end of this period, a minimum 

 of easterly winds. While I have been completing this report the cholera 

 has broken out in Egypt, and a strict quarantine has been established in 

 all the Syrian ports. In this connection, therefore, it may be of interest to 

 add a note respecting the climate of Jerusalem in October, 1865, when the 

 cholera raged in this city with considerable violence. The period from the 

 seventh to the twenty-fourth of that month was one of great and oppressive 

 heat. During the whole eighteen days the sky was cloudless, but over- 

 spread with a thin haze. The wind was from northwest, north, and east, 

 but so light as to be considered a calm, except on the fifteenth and six- 

 teenth, when there was a light breeze from the east. The highest temper- 

 ature was ninety-four degrees, and on eleven days it rose to at least ninety 

 degrees. During the period the mean of the maximum temperature was 

 89.1, and of the minimum temperature 65.8; the mean temperature for 

 the period being 77.4 degrees. This high temperature, together with the 

 calm, close, hazy atmosphere, was supposed to have some influence in 

 spreading the cholera. 



