KILNS, LUMBER. hi these clays of rapid conversion of material, and of short periods between the various processes of conversion, little could be done by the converter of wood without the aid of efficient lumber-drying kilns, taking the place of the old-fashioned long seasoning process in air or water.
An automatic hot-blast apparatus, put out by the Standard Dry Kiln Co., consists of a high-speed blowing-fan, directly driven by an inverted vertical high-speed engine, and con nected with a case or chamber in which there are arranged a series of vertical spiral coils of pipe, through and about which the air enters before being removed by the fan. Into one of the series of pipes (that farthest from the engine and nearest to the entrance of the air to be heated) the exhaust of the engine is led, thus receiving the greatest amount of condensation that could be obtained by such an arrangement, and lessening the back-pressure upon the engine. Some of the rest of the coils in the duct or chamber receive live steam, if desired, but the connections are such that as many as desired receive the exhaust from the main or steam-engine. A steam-jet regulates the degree of humidity of the air. A steam-trap, through which the water of condensation drains when live steam is being used, regulates the amount consumed.
A hot-air duct used in this device has a regulator for controlling the delivery of air to each opening in the duct, preventing the air from rushing by the openings nearest the blower. A series of semi-cylindrical slides drop from the cross-outlets into the body of the main duct, thus retarding the air and forcing it out through the cross-duets into the kiln. The cross
duct nearest the heater ordinarily has its slide projecting farthest into the main duct, although, if desired, any one section of the kiln may be given an increased proportion of air.
In the Standard kiln the lumber is loaded upon ears at what is called the "green end," and run into the kiln on iron tracks at the rate of two or more cars per day, in each of the rooms composing the kiln. Each ear holds about 4,000 ft. of lumber. and each room will contain 12 caws; so that the lumber while in transit remains in the drying process from 3 to 0 days, depending upon the class of stock, before it is run out at the "dry end " of the kiln. The temperature at the end of the kiln in which the heated air centers, and at. which point the process of seasoning is completed, is about 185' F., corresponding to an absorbing capacity of 191 gr. per cub. ft. of air. At that end at which the lumber enters, where the temperature is 125° h'., the absorbing capacity is only about 30 gr., so that the action is gradually increasing —being in this particular much easier upon the stock, drying it more thoroughly and greatly lessening checking.
K nutter: see Ilarvesting-Machines, Knox System of see Qimarrying-Machines.
K ing-Tool : see Metal-Working. Ladders, Fire: see Fire ArionaneeS. Land Roller : see Seeders and Drills.
La pp i ne : See Grinding-Machine.
Last tig-31 ail] Inv : see Deat her- Working Machines.
Lathe : see I hit-Making Machines, Watches and Clocks, Wheel-Making machines, Mowers and Reapers.