SCIENTIFIC MISCELLANEA. 173 



Wewils. — M. Vallery has read to the Academy of Sciences at Paris a paper 

 upon a new method of preventing the ravages of Wewils, and other insects, 

 on corn in granaries. His plan is founded upon the observation of the habits 

 of these animals ; and it has the farther advantage of obviating the fermenta- 

 tion that takes place in grain when laid up in heaps. Having ascertained 

 that these insects never breed unless in a state of quietude, and at a certain 

 elevation of temperature in the surrounding medium, he proposes by fre- 

 quently stirring and turning the grain and exposing it to the air, thus to 

 prevent its fermentation, and at the same time the propagation and increase 

 of the Wewils. 



Temperature M. Arago has published an article to prove that the 



temperature of the Holy Land has not sensibly changed since the time of 

 Moses. The Duke of Kagusa (Marshal Marmont) in a letter to the Acade. 

 my, disputes the grounds of this assertion and of a similar one respecting 

 Egypt. M. Argo states that there are now scarcely any Palm trees in Pales- 

 tine, and those that exist are almost barren ; whereas, there are some at Home 

 that bring their fruit to perfection. The limits assigned to the vine are also 

 contested. It is stated in the article, that the vine is not productive where 

 the mean temperature is above 70° Fah., as is the case at Cairo ; but there 

 are vineyards still at Fayoum, the hottest province of Egypt, that produce 

 exellent wines ; and the cultivation of the grape is extending. The Mar- 

 shal's letter also contains a note on the change of temperature in Lower 

 Egypt. Formerly it scarcely ever rained, and only for a short time at 

 Alexandria, now it rains there for thirty or forty days annually, and some- 

 times after the middle of October it does not cease for five or six days toge- 

 ther. At Cairo, instead of a few drops falling, and those rarely, there are 

 from fifteen to twenty rainy days every winter. It is supposed that this 

 change of climate is owing to the immense plantations of the Pacha, twenty 

 millions of trees having been planted below Cairo. What countenances this 

 idea is the contrary effect that has been produced in Upper Egypt by the 



destruction of the trees there The following are the results obtained by 



M. Mollet, from some experiments performed with much care on the effect 

 produced upon the temperature of the soil by a covering of turf. With 

 only two exceptions the temperature under the turf was higher than at an 

 equal depth in the bare soil ; amounting in the morning sometimes to 3° Fah., 

 and generally to one degree at night at eight o'clock, — the morning hour of 

 observation being nine. The experiment was continued for a month. [It is 

 to be regretted that the time of year at which the experiment was made is 

 not given ; and that the experiment was not continued for a whole year. 

 Had this been done, considerable light might have been thrown upon the 

 question of changes of climate in ancient and modern times effected by culti- 

 vation. At present, the general idea is that a country covered with vegeta- 

 tion is hotter in summer and colder in winter, than where the soil is bare ; 

 such at least is the result of observation in the United States from the clear- 

 ing of the woods — Ed.] 



