MINING CLAY FOR BUILDING-BRICK.
One of the great difficulties usually encountered by the man ufacturers of building-brick who have established extensive works near large bodies of clay is to get sufficient clay dug, loaded, and elevated to meet the demand for the material. Along the banks of the Ohio River where the brick clay ranges from 25 feet to 35 feet in depth, and which clay is of a tough and lumpy nature, and often runs into the wet-stiff-blue clay, it is hard to obtain, except at large expense, laborers to dig, cave, and shovel the material.
By this method the cost of placing the clay in the tempering shed averages fifty cents per thousand in the locality named, and as there is no certainty of a full supply of clay for each day's work, the result is short time and no assurance of any regular output of brick.
Men in caving are often caught in the falling bank and be come disabled, and it makes them wary of undertaking the " job " again, and consequently it becomes extremely hard to employ labor for that class of work.
There are a large number of mechanical clay-diggers now manufactured and designed to perform the work described, but the Barnhart steam shovel, shown in Fig. 15, will dig clay enough for from 150,000 to 200,000 brick daily, and by its use moder ate-sized yards can enlarge their capacity as desired.
The steam shovel shown in Fig. 15 is built by the Marion Steam Shovel Company, Marion, Ohio, and the machine is self propelling and cuts the clay to a height of 18 feet, and will load 30o to 400 cubic yards per day. It digs the clay from top to bottom of bank, thoroughly mixing it. It is built on a solid frame-work upon standard gauge-wheels, and can be moved any distance backward or forward simply by laying a track. At night it can be locked up securely from intrusion by meddlers, as it has a substantial cab built over it. It is the cheapest, best, and simplest machine we know for the purpose, and gives entire satisfaction. It is operated by an engineer, one crane boy and an outside man. Formerly it took eight men to do
this work. These diggers hardly pay on works making less than 50,000 brick per day. A smaller and less costly steam shovel would dig the clay for 50,000 brick daily, if properly constructed and the clay to be dug is not too tough.
The Purington-Kimball Brick Co., of Chicago, Ill., has sub stituted electric power for steam in operating steam-shovels used for the digging of clay, owing to the difficulty experienced in getting coal to the shovel.
Manufacturers of brick whose plants are located in the cen tral or elevated portions of the country, can readily appreciate the advantage in digging clay, which others have who possess inexhaustible banks of clay near at hand.
Some manufacturers in the interior of the country have to haul their clay half a mile or a longer distance, and in some cases eighteen inches to two feet is the maximum depth. Even scrapers and ploughs in such instances are impracticable, and the only way to dig such clay is to turn it over, let the weather slack it, and by muscle and good strong horses and carts move it away. It takes sixty-four cubic feet of clay to make a thous and brick, and a cart having a haul of one-half mile makes about twelve loads for a day's work, and this seems to be the most advantageous method of moving clay that distance.
Manufacturers of brick having banks of clay eight or ten feet in depth often plow the clay when they have satisfactory ar rangements for mixing it ; but when the clay cannot be properly mixed it is better to " fall " the bank, and in that way mix the top and the bottom and the strong and the weak clay. Where fifty thousand brick are made per day, and the clay is only two or three hundred yards away, five men and three horses and carts should be sufficient to move the clay to the crushers or pulverizers.