10 per cent. of the number, but not of the mileage, of the whole; for most of this class run short journeys.
Not reckoning mileage west of Exeter.
IMPROVED OIL MILL.
The old and cumbersome methods of crushing oil seeds by mechanical means have during the last few years undergone a complete revolution. By the old process, the seed, having been flattened between a pair of stones, was afterward ground by edge stones, weighing in some cases as much as 20 tons, and working at about eighteen revolutions per minute. Having been sufficiently ground, the seed was taken to a kettle or steam jacketed vessel, where it was heated, and thence drawn—in quantities sufficient for a cake—in woollen bags, which were placed in a hydraulic press. From four to six bags was the utmost that could be got into the press at one time, and the cakes were pressed between wrappers of horsehair on similar material. All this involved a good deal of manual labor, a cumberstone plant, and a considerable expense in the frequent replacing of the horsehair wrappers, each of which involved a cost of about £4. The modern requirements of trade have in every branch of industry ruthlessly compelled the abandonment of the slow, easy-going methods which satisfied the times when competition was less keen. Automatic mechanical arrangements, almost at every turn, more effectually and at greatly increased speed, complete manufacturing operations previously performed by hand, and oil-seed crushing machinery has been no exception to the general rule. The illustrations we give represent the latest developments in improved oil-mill machinery introduced by Rose, Downs & Thompson, named the "Colonial" mill, and recently we had an opportunity of inspecting the machinery complete before shipment to Calcutta, where it is being sent for the approaching exhibition. As compared with the old system of oil-seed crushing, Messrs. Rose, Downs & Thompson claim for their method, among other advantages, a great saving in driving power, economy of space, a more perfect extraction of the oil, an improved branding of the cakes, a saving of 50 per cent. in the labor employed in the press-room, with also a great saving in wear and tear, while the process is equally applicable to linseed, cottonseed, rapeseed, or similar seeds. In addition to these improvements in the system, the "Colonial" mill has been specially designed in structural arrangement to meet the requirements of exporters. The machinery and engine are self-contained on an iron foundation, so that there is no need of skilled mechanics to erect the mill, nor of expensive stone foundations, while the building covering the mill can, if desired, be of the lightest possible description, as no wall support is required. The mill consists of the following machinery: A vertical steel boiler, 3 ft. 7 in. diameter, 8 ft. 1½ in. high, with three cross tubes 7½ in. diameter, shell 5/16 in. thick, crown 3/8 in. thick, uptake 9 in. diameter, with all necessary fittings, and where wood fuel is used extra grate area can be provided. This boiler supplies the steam not only for the engine, but also for heating and damping the seed in the kettle. The engine is vertical, with 8 in. cylinder and 12 in. stroke, with high speed governors, and stands on the cast iron bed-plate of the mill. This bed-plate, which is in three sections, is about 30 ft. long, and is planed and shaped to receive the various machines, which, when the top is leveled, can be fixed in their respective places by any intelligent man, and when the machines are in position they form a support for the shafting. The seed to be crushed is stored in a wooden bin, placed above and behind the roll frame hopper. The roll frame has four chilled cast iron rolls, 15 in. face, 12 in. diameter, so arranged as to subject the seed to three rollings, with patent pressure giving apparatus. These rolls are driven by fast and loose pulleys by the shaft above. After the last rolling the seed falls through an opening in the foundation plate in a screen driven from the bottom roll shaft by a belt. This conveys the seed in a trough to a set of elevators, which supply it continuously to the kettle. This kettle, which is 3 ft. 6 in. internal diameter and 20 in. deep, is made of cast iron and of specially strong construction. There is only one steam joint in it, and to reduce the liability of leakage this joint is faced in a lathe. The inside furnishings of the kettle are a damping apparatus with perforated boss, upright shaft, stirrer, and delivery plate, and patent slide. The kettle body is fitted with a wood frame and covered with felt, which is inclosed within iron sheeting. The crushed seed is heated in the kettle to the required temperature by steam from the boiler, and it is also damped by a jet of steam which is regulated by a wheel valve with indicating plate. When the required temperature has been obtained, the seed is withdrawn by a measuring box through a self-acting shuttle in the kettle bottom, and evenly distributed over a strip of bagging supported on a steel tray in a Virtue patent moulding machine, where it undergoes a compression sufficient to reduce it to the size that can be taken in by the presses, but not sufficient to cause any extraction of the oil. The seed leaves the moulding machine in the form of a thick cake from nine to eleven pounds in weight, and each press is constructed to take in twelve of these cakes at once. The press cylinders are 12 in. diameter and are of crucible cast steel. To insure strength of construction and even distribution of strain throughout the press, all the columns, cylinders, rams, and heads are planed and turned accurately to gauges, and the pockets that take the columns, in the place of being cast, as is sometimes usual, with fitting strips top and bottom, are solid throughout, and are planed or slotted out of the solid to gauges. The pressure is given by a set of hydraulic pumps made of crucible cast steel and bored out of the solid. One of the pump rams is 2½ in. diameter, and has a stroke of 7 in. This ram gives only a limited pressure, and the arrangements are such as to obtain this pressure upon each press in about fourteen seconds. This pump then automatically ceases running, and the work is taken up by a second plunger, having a ram 1 in. diameter and stroke of 7 in., the second pump continuing its work until a gross pressure of two tons per square inch is attained, which is the maximum, and is arrived at in less than two minutes. For shutting off the communication between the presses, the stop valves are so arranged that either press may be let down, or set to work without in the smallest degree affecting the other. The oil from the presses is caught in an oil tank behind, from which an oil pump, worked by an eccentric, forces it in any desired direction. The cakes, on being withdrawn from the press, are stripped of the bagging and cut to size in a specially arranged paring machine, which is placed off the bed-plate behind the kettle, and is driven by the pulley shown on the main shaft. The paring machine is also fitted with an arrangement for reducing the parings to meal, which is returned to the kettle, and again made up into cakes. The presses shown have corrugated press plates of Messrs. Rose, Downs & Thompson's latest type, but the cakes produced by this process can have any desired name or brand in block letters put upon them. The edges on the upper plate, it may be added, are found of great use in crushing some classes of green or moist seed. The plant, of which we give illustrations opposite, is constructed to crush about four tons of seed per day of eleven hours, and the manual labor has been so reduced to a minimum that it is intended to be worked by one man, who moulds and puts the twenty-four cakes into the presses, and while they are under pressure is engaged paring the cakes that have been previously pressed. In crushing castor-oil seed, a decorticating machine or separator can be combined with the mill, but in such a case the engine and boiler would require to be made larger.—The Engineer.
APPARATUS FOR SEPARATING SUBSTANCES CONTAINED IN THE WASTE WATERS OF PAPER MILLS, ETC.
For extracting such useful materials as are contained in the waste waters of paper mills, cloth manufactories, etc., and, at the same time, for purifying such waters, Mr. Schuricht, of Siebenlehn, employs a sort of filter like that shown in the annexed Figs. 1 and 2, and underneath which he effects a vacuum.