Alaska sentinel., 1908-08-06
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As we reach lower and lower depths the water becomes colder; the warm water, being less dense, remains at the surface. At about 12oOO feet the tenn perature Is little above the freezing point of fresh water. Light gradually disappears, and at 1,40O feet, says Country Life, absolute darkness pre- yails; and as no plant can live without light, the vegetable kingdom Is unrep- resented, except by some boring algae which have been dredged from a depth of over 5000 feet. Further, there are no currents. oxygen Is scarce and uni formity of temperature prevails.
 Prof. A. Herschel, In the Quarterly Journal of the Royal Meteorological Society, describes the extraordinary eff fects produced by lightning in the midst of an open moor In Northumber- land. A hole or feet in diameter was made in the flat, peaty ground, and from this half dozen furrows ex- tended on all sides. Pieces of turf were thrown In various directions, one 8 feet In diameter and a foot thick hay Ing fallen 7S feet from the hole. Inves- tigstlon showed that In addition to the effects visible on the surface, small holes had been bored In the earth ra- diating from the large excavation. Many readers may recall the surpris> they felt on reading Darwin's book on earthworms to find how the great nat hnl nhar to so apparently unpromlsing subject. It led them to entertain a respect they had never previously felt for the hum ble borers In the earth. It now appears that earthworms must be regarded as useful otherwise than as simple culti- yators and renewers of the soil. Ac- cording to E. A. Andrews. they are tree planters also. They draw the flat seeds of the silver maple into their burrows, and such seeds, In districts too dry for them to germlnate If left upon the surface, sprout from the wormholes, and grow Into seedlings, which, under favoring conditions, may become flour. ishing trees.
 Maj. W. V. Judson, the goyernmen. engineer In charge of harbor work at Milwaukee, Wis, is reported by the Railway and Engineering Review to be experimenting with re-enforced con- crete blocks, made hollow, so that they can be foated to place In constructing the government breakwater at that point. The proposed block of standard size will weigh about fourteen tons, but In the experiments the weight Is only about seven tons. The blocks will consist of re-enforced concrete walls, inclosing a hollow space. After It has been lowed to the site of the work an opening in the bottom Is uncovered and water Is permitted to enter the block and sink It. The interior of the block is then filled with sand and gravel, and the open space In the top Is filled with concrete.
 This question, always interesting for the light 1t throws On the past history of the earth, has had many answers. The latest Is that of pr. J. W Spencer, who, from recent studies on the spot, l finds that the mean rate of recession of Niagara falls at present Is 42 feet per year. and this has been the rate for ap- proximately 227 years. But owing to the fact that originally the waters of Lake Erie only were discharged over the falls, giving but one fifteenth of the present water supply, the rate of re- cession was at first much lower. A sud den widening of the gorge above Eos ter's Flat indicates the position of the falls when the other great lakes began to discharge Into Lake Erie. From his data, pr. Spencer calculates the entire age of the falls at 5000 years. Tho cutting, with the full power of the four lakes, Is estimated to have lasted $500 years.