The wells in the Oil Springs field were formerly from 200 ft. to 300 ft. in depth, but the oil stratum then worked became waterlogged, and the wells are now sunk to a depth of about 375 ft., and are cased to a depth of about 275 ft. to shut off the water. The contract price for drilling a 4-5/8 in. hole to a depth of about 375 ft. under the conditions mentioned is 150 dols. (L30), and the time occupied in drilling is usually about a week when the work is continued night and day. The wells in the Petrolia field have a depth of 480 ft., the contract price, including the cost of 100 ft. of wooden conductor, being 175 dols. (L35), and the time occupied in drilling being from six to twelve days. Pole tools are used in drilling, the poles being of white ash, 37 ft. in length. The derrick is about 48 ft. in height. An auger some 4 ft. in length, and about a foot in diameter, is used to bore through the earth to the bed rock, the auger being rotated by horse power. The drilling tools commonly consist of a bit, 21/2 ft. in length by 4-5/8 in. in diameter, weighing about 60 lb.; a sinker bar, into which the bit is screwed, 30 ft. in length by 3 in. in diameter, weighing about 1,040 lb.; and the jars, inserted between the sinker bar and the poles about 6 ft. in length, and weighing 150 lb. The tools are suspended by a chain, which passes three times round the end of the walking beam and thence to the windlass, with ratchet wheel fixed on the walking beam, by means of which the tools are gradually lowered as the drilling proceeds. The cable is thus only employed in raising the tools from the well and lowering them into it. The sand pump or bailer is frequently as much as 37 ft. in length, and is about 4 in. in diameter. The casing (4-5/8 in diameter) costs about 45 cents (1s. 101/2d.) per foot, and the 11/4 in. pump, with piping, costs from 65 dols. (L13) to 85 dols. (L17), according to the length of pipe required. An ordinary square frame derrick costs, with mud sill, from 22 dols. (L4 8s.) to 27 dols. (L5 8s.), and the walking beam about 8 dols. (L1 12s.) In many cases, however, a three-pole derrick, which can be erected at an expense of about 10 dols. (L2), is employed. A 100 barrel wooden tank costs, erected, 50 dols. (L10). THE CANADIAN TORPEDO.