190 
INFLUENCE OF THE FOKEST ON PRECIPITATION. 
the roofs in Alexandria, without being covered or otherwise 
protected from injury by the atmosphere ; but since the mak¬ 
ing of plantations, an obstacle has been created which retards 
the current of air from the north. The air thus checked, accu¬ 
mulates, dilates, cools, and yields rain.* The forests of the 
* The supposed increase in the frequency and quantity of rain in Lower 
Egypt is by no means established. I have heard it disputed on the spot 
by intelligent Franks, whose residence in that country began before the 
plantations of Mehemet Aali and Ibrahim Pacha, and I have been assured 
by them that meteorological observations, made at Alexandria about the 
beginning of this century, show an annual fall of rain as great as is usual 
at this day. The mere fact, that it did not rain during the French occu¬ 
pation, is not conclusive. Having experienced a gentle shower of nearly 
twenty-four hours’ duration in Upper Egypt, I inquired of the local gov¬ 
ernor in relation to the frequency of this phenomenon, and was told by 
him that not a drop of rain had fallen at that point for more than two 
years previous. 
The belief in the increase of rain in Egypt rests almost entirely on the 
observations of Marshal Marmont, and the evidence collected by him in 
1836. His conclusions have been disputed, if not confuted, by Jomard 
and others, and are probably erroneous. See, Foissao, Meteorologie , Ger¬ 
man translation, pp. 634-639. 
It certainly sometimes rains briskly at Cairo, but evaporation is exceed¬ 
ingly rapid in Egypt—as any one, who ever saw a Fellah woman wash a 
napkin in the Kile, and dry it by shaking it a few moments in the air, can 
testify; and a heap of grain, wet a few inches below the surface, would 
probably dry again without injury. At any rate, the Egyptian Govern¬ 
ment often has vast quantities of wheat stored at Boulak, in uncovered 
yards through the winter, though it must be admitted that the slovenliness 
and want of foresight in Oriental life, public and private, are such that we 
cannot infer the safety of any practice followed in the East, merely from 
its long continuance. 
Grain, however, may be long kept in the open air in climates much 
less dry than that of Egypt, without injury, except to the superficial 
layers; for moisture does not penetrate to a great depth in a heap of grain 
once well dried, and kept well aired. When Louis IX was making his 
preparations for his campaign in the East, he had large quantities of wine 
and grain purchased in the Island of Cyprus, and stored up, for two years, 
to await his arrival. “ When we were come to Cyprus,” says Joinville, 
Histoire de Saint Louis, § § 72, 73, “ we found there greate foison of the 
Kynge’s purveyance. * * The wheate and the barley they had piled 
