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THE POPULAR SCIENCE MONTHLY. 



opened for the admission of air, the French 

 employ the vertical division, and open the 

 windows inwardly on hinges as we open 

 doors. The window apertures are also 

 large, or rather high, descending to within 

 eighteen inches of the floor, and ascending 

 to within four inches of the ceiling. Out- 

 side these are latticed shutters. When the 

 windows are open and the shutters closed 

 the sun is effectually kept out, and the free 

 circulation of the air is scarcely interfered 

 with. A light balustrade of iron, within 

 the shutters and without the glass, serves 

 to prevent falling through the windows." 



Destruction of American Forests.— It 

 has been for some years apparent that the 

 United States supply of timber must fail at 

 no distant day, unless some concerted meas- 

 ures are taken for growing new forests or 

 in soTie way preserving the old. The pres- 

 ent condition of the lumbering business will 

 be understood from the following facts, pub- 

 lished by the St. Paul " Pioneer Press," and 

 based on the observations of Mr. James 

 Little, a lumber-merchant of Montreal, who 

 has long studied this subject: Of the twen- 

 ty-six States comprising the Xew England, 

 Middle, Western, and Northwestern, to the 

 Kocky Mountains, only four are now able to 

 furnish lumber-supplies beyond their own 

 requirements ; the four being Maine, Michi- 

 gan, Minnesota, and Wisconsin. But Maine 

 is almost stripped of her pine-forests, and 

 lumberers have to go to the head-waters of 

 the rivers in search of spruce, while mere 

 saplings, six or seven inches in diameter, go 

 to the mill. In a few years Maine will have 

 neither pine nor spruce for home consump- 

 tion. The northern parts of Michigan, Wis- 

 consin, and Minnesota, are the only locali- 

 ties of the whole twenty-six States which can 

 furnish supplies of white pine beyond the 

 home demand ; but they will not be able to 

 do so, Mr. Little affirms, for more than five 

 or six years longer. The main streams are 

 all stripped, and the dependence of the lum- 

 bermen is now on the head-waters of the 

 tributaries. In 1870, according to the cen- 

 sus report, there were in the United States 

 173,450 industrial establishments, employ- 

 ing 1,093,202 hands, devoted to the manu- 

 facture of wooden articles. The impression 

 prevails that when our supply of lumber 



fails, as it must inevitably within the next 

 ten years, we can find in Canada a supply 

 that will not be exhausted in centuries. 

 But this is an error; at least, Mr. Little 

 asserts that there is not from Manitoba to 

 the Gulf of St. Lawrence as much pine, 

 spruce, hemlock, white-wood, and other 

 commercial timber, as would supply the 

 United States for even three years ! In 

 the light of such facts as these, it behooves 

 the people of this country to seriously con- 

 sider the subject of reforestation and the 

 protection of young timber-trees. 



Blovenient of Water in the Suez Canal. 



— The currents of the Suez Canal and the 

 action of the prevalent winds on the water 

 therein have been studied by M. Lemasson, 

 who finds that Lake Timsah and the basin 

 of the Bitter Lakes, the former in the mid- 

 dle of the line of navigation, the latter near- 

 ly at the middle of the southern branch of 

 the canal, constitute two great regulators, 

 at which the tidal currents from the two 

 seas respectively expire. The north and 

 south branches of the canal are not, how- 

 ever, independent as regards the movement 

 of their waters. The dominant winds in 

 this region blow, from May to October, from 

 the north and northwest, and raise the mean 

 level of the waters of the Mediterranean at 

 Port Said, while they depress the mean level 

 at Suez. The difference of level, which at- 

 tains almost sixteen inches in September, 

 sets up, in summer, a current from the 

 Mediterranean to the Red Sea, which is in- 

 terrupted by the tides, but nevertheless car- 

 ries a considerable volume of water from 

 north to south. In the winter, on the con- 

 trary, the south winds blow strongly, and 

 the mean level of the Red Sea is then high- 

 er than that of the Mediterranean, the dif- 

 ference attaining a maximum of nearly one 

 foot. The general direction of the current 

 of the canal then sets from the Red Sea to 

 the Mediterranean. The volume of water 

 flowing annually from sea to sea is estimated 

 at 400,000,000 cubic metres, and this with 

 the tidal currents annihilates the effects of 

 evaporation at the surface of the lakes, and 

 aids the solution of the great salt deposit 

 in the basin of the Bitter Lakes, which, in- 

 stead of increasing, is diminishing, espe- 

 cially in the line of transit of ships. 



