ICE-SAWS. Large saws used for cutting through the ice for relieving ships when frozen up. The vessels employed in the Greenland fisheries, and others that navigate the polar seas, are regularly furnished with these machines, as the lives of the crew not unfrequently depend on the expedition with which a can be cut, so as to disengage the vessel befare the further accumu ice renders it an The saw, with a weight suspended to it, is introduced by means of a hole broken through the ice, and is suspended by a rope passed over a pulley fixed to a triangle. A party of a dozen or more men, run out and back again with a rope, and thus move the saw up and down till it has cut its way so far as to hang perpendicularly from the pulley. The triangle is then moved a foot or two farther, and the sawing recommences, the services of the whole crew being required in this laborious undertaking.
Lieut. W. J. Hood, of the Hyperion, R.N. has recently greatly improved this apparatus; for the communication of which and the presentation of an illustrative model to the Society of Arts, that gentleman was awarded the Society's honorary medal. In Mr. Hood's machine, the saw is suspended by a slight sledge, and is worked by the power of only two or three men at the end of a lever; a bar, called a propeller, is fixed on the lever between the ful crum and the saw, the other end resting on the surface of the ice, and so adjusted that each motion of the lever shall produce a cut of a given length, and at the same time, by means of the propeller, push the sledge on, so that the teeth of the saw shall always be in contact with the ice. The annexed figure gives a side elevation of the machine. a a a is a sledge, of open frame-work,
ing on the surface of the ice ; b a transverse bar passing through the lever c c, and forming the fulcrum on which it moves; this lever has a cross handle, as represented in perspective in dotted lines; e a clamp or brace consisting of two cheeks, one on :each side of the lever, loosely pinned at top to the lever, and at bottom to the saw f ; g a clamp similar to e, by which the weight d (which is of the shape of a double convex lens) is hung to the lower end of the saw; i the propeller, an iron bar, terminating below in two claws, and at top in a fork, and suspended on the lever by means of a transverse pin k ; 1 a weight hung to the propeller at nr ; a a transverse bar, limiting the motion of the handle end of the lever in an upward direction. It should be understood that there is a duplicate frame similar to that brought into view, on the other side of the machine, about 18 inches apart, and connected by transverse bars. To prevent the lever from swerving laterally, there are at the handle ends two upright bars, between which the lever moves. The saw, after having once entered the ice, will only require from two to four men to work it ; and it should not be taken out of the ice till after the distance required to be cut through is accom plished. The saw can be guided by the lever in any direction, so as to cut the ice into pieces moat convenient for removal, either by pushing them under the adjacent floor of ice, or by dragging them out of the ship's track into clear water.