Science Siftings

New Zealand Tablet, 3 August 1911, Page 1491

Science Siftings

By ‘ Volt.’

Protection for Physicians. Dr. Paul Aubourg, of Paris, has designed garments for physicians operating the X-rays which ' will ensure protection from all harmful effects. The outfit consists of a rubber, mask with spectacles of a lead glaze, a long blouse made of lead, rubber, and bismuth, and thick gauntlets of the same materials. Power of Niagara. What makes Niagara Falls’ power possible is the fact that Lake Superior, Lake Michigan, Lake Huron, and Lake Erie, with a combined area of 90,000 square miles, representing the reservoirs of some 250,000 square miles of watershed, are situated 600 feet above the sea level. The great volume of water falling over the vast territory flows on its natural course to the Atlantic ocean with but a slight descent until it is brought into the narrow Niagara River, when, in the rapids just above the falls, it declines 55 feet and then, with a single plunge, drops into the abyss 165 feet below. Eminent engineers have computed that 275,000 cubic feet of water pass over the falls every second, representing in theoretical energy over 6,000,000 horsepower. A Waterspout. A waterspout is a miniature tornado originating in a strong upward draught of air which occurs above the surface of a body of comparatively warm water. Its effect first becomes visible in a circular motion at the point in the clouds to which it ascends. This becomes a whirl, which condenses the vapor at its centre, causing the portion of the cloud there to drop downward in the shape of a gigantic jelly-bag. At the same time the continuing upward draught increases the rapidity of its original swirl and the condensed vapor caught within it until the ascending and descending masses join to form the waterspout. Necessarily by this process the air beneath the spout is rarified, and thus where the phenomenon occurs at sea the water always seems to be sucked up into it, although this is not really the case to any considerable extent. For similar reasons where a waterspout or tornado passes over a building it does most of its damage by exhausting the air outside, causing what is within to expand and blow the structure to pieces. Wire for Felling Trees. From Berlin comes the news that a device reported some years ago on this side of the world is in actual use in Germany for felling trees. The trunks are cut by the' friction of a. steel wire one-millimetre in diameter which, as demonstrated by practical tests, is able to cut through a tree about 20 inches in thickness in six minutes. The wire, which is carried to and fro by an electric motor, is heated by friction on the tree to such an extent as to burn through the timber, the result being a cut which is both smoother and cleaner than that effected by saw. The wire, it is said, will work satisfactorily on the thickest trees without the insertion of wedges into the cut, and the trees may be cut immediately above or below the ground. In the latter case the stump may be left safely in the soil. The motor which actuates the wire is placed outside of the range affected by the fall of the tree, and when electricity is not already available it can be generated by a transportable power plant consisting of a 10horse power gasoline motor and dynamo, which are left at the entrance of the forest during the felling operations.