Useful Numbers for Single-Acting Pumps. D= diameter of pump in inches. Formula to find Horse Power of Pumping Engines. G= the number of gallons required per hour. C the number of cubic feet required per hour. F the height in feet to which the water is to be raised. Add 70 per cent to the number obtained by the above formula to allow for friction, leakage, &c. The result obtained is not nominal, but actual horse-power (33,000 foot lbs.). USEFUL RULES. To find the Pressure per Square Inch of a Column of Water (Telford). Multiply the height in feet by 434. The pressure per circular inch may be found by multiplying the height in feet by 341. Example.-Required the pressure in pounds per square inch of a column of water 200 feet high. 200 X 434 86.8 lbs. per square inch. A ready way of ascertaining approximately the pressure is to take half the height in feet, the difference being on the side of safety. To find the Pressure of a Column of Water in Pounds. If the base be circular, square the diameter in inches and multiply by 341 or 34, which gives the weight of one foot in height; therefore, by multiplying by the number of feet in height, the pressure is found. If the base be square, multiply by 434. Example.-Required the pressure of a column of water 12 inches in diameter and 20 feet high, 12 X 12 X 341 X 20982-080 lbs. if the base be circular. To find the Quantity of Water in a Pipe. The square of the diameter in inches gives the weight of water in pounds for 3 feet in length, and by striking off one figure to the right the number of gallons is found. Example.-Required the quantity of water which a pipe 15 inches diameter and 9 feet long will contain. 15 X 15 X3 = 675 lbs., or 67.5 gallons. For large cylinders where both the dimensions are in feet, the following rule (Griffin) is easily calculated, and is sufficiently accurate for ordinary use. Multiply the square of the diameter by five times the depth, the result being the number of gallons approximately. By deducting 2 per cent. the exact quantity may be more nearly ascertained. The actual contents of a cylinder in gallons is found by multiplying the square of the diameter in feet by the depth in feet and then by 4.8994, which is nearly 5. Example.-Required, the quantity of water which a cylinder 4 feet diameter and 5 feet long will contain. 4 X 4 X 25 = 400 gallons, or after 2 per cent. has been deducted 392. The actual contents are 391.79 gallons. If either or both dimensions be in inches the result has to be divided a proper number of times by 12. A pipe 3 inches diameter and 3 feet long holds 18ths. of a gallon, or 7 pints roughly; after taking off 2 per cent., 7.35 pints, the actual contents are 7.346 pints. 3 × 3 × 15 = 135 ÷ 144 = ·938 gallons. To find the Quantity of Water in Gallons delivered by a Pump per Minute. Square the diameter in inches and multiply by ·034 and the product by the speed in feet. Example.-Required, the quantity of water delivered by a pump 10 inches in diameter and working at the rate of 40 feet per minute. 10 X 10 X 034 × 40 = 136 gallons per minute. CHAPTER VII. AGRICULTURAL MACHINERY, MANAGEMENT OF THRASHING MACHINES, &c. WE have elsewhere given rules as to the management of portable engines, &c., and we now purpose giving some instructions as to the working of a machine used largely in conjunction with them, viz. the thrashing machine. This is the most complex of agricultural machines, and being somewhat liable to disarrangement it requires careful handling and management to secure clean and effective working. Its manufacture and operation being somewhat of a speciality we cannot do better than give some of the directions for working issued by a celebrated maker (Ruston), who says: "The first point to attain so as to insure a correct working of the machine is to place it in a proper position, which should be as nearly horizontal as possible. The next is to judge the distance-about 30 feet from centre to centre-it should stand from the engine, care being taken that the fly-wheel of the engine is in a true line with the side of the machine, and exactly fair with the driving drum. All four wheels of the machine must be blocked truly level in all ways, and then both machine and engine must be securely wedged. A disregard of these instructions often entails the running off of belts or of injuring them, and generally tends to the imperfect working of the machine. "The thrashing machine now being ready for work and duly oiled should work empty for a short time-the sound of the machine will at once indicate its fitness to commence work. "To ensure a perfect thrashing of the grain the most important thing to attend to is to properly regulate the drum beater concave to suit the class of grain required to be thrashed, for which purpose adjusting screws are provided on each side, and small peep-holes by which to observe and measure the distance of the beaters from the face of the concave. Upon this adjustment depends the result of the day's work If too wide a space is left between the drum and the concave, the straw will leave the machine not thoroughly clean of grain, and if too little space is left both grain and straw will be bruised. "Barley and large wheat will require the widest opening, that is to say, at the top 1 inch, middle § inch, and inch at the lower point. "For rye, poor wheat, and oats, at the top 1 inch, middle inch, and inch at the lower point. When the grain is brought damp from the field it will be found in practice necessary to deviate slightly from the above figures, and to ensure a proper result a constant observation of the thrashing is necessary, and thus to regulate the machine from time to time during a day's work according to the growth of the cereal which requires to be thrashed of its grain. We shall treat further on the operation of thrashing beans, peas, rape, and clover. "After carefully adjusting the beaters and concave to suit the work, test the distance by the hand, and secure the double nuts tightly so that the concave cannot shift. "However solidly built a machine may be, it is of the greatest importance for those in charge to make a thorough inspection before starting work, to tighten up all nuts and screws that may be discovered to be loose. Attention to this will prevent many a vexatious delay. Most of these defects can be detected by the sound as soon as the machine begins to move. "Frequently it happens that inexperienced workmen set to work with hammer and chisel, doing more harm than good. Proper spanners are supplied with the machine, these only should be used to tighten up bolts, and the lids of all bearings should be opened by the hand, not knocked up with the hammer. Much depends, especially in winter, upon a careful and systematic oiling of all parts having motion, and it is also requisite that all oil cans and tins be kept quite clear of dirt. No machine is more subject to inconvenience from dust than a thrashing machine, and it is the duty of the man in charge of the engine, who should take no part in the thrashing, to carefully see that all parts in motion are free from straw and dirt, and to lubricate the bearings and see that all oil-box covers are securely closed. "The drum will require the most attention, for if this should run hot the entire day's work may be lost. The correct and true position of the machine will, together with good oiling, render this danger next to an impossibility. "Next to the drum the smutter shaft and the blast fans revolve with the greatest speed. These will require to be oiled three or four times daily. The grain elevators and straw shakers, when in good order, would require but twice oiling. "Behind the separating screen is the four-cranked axle, giving backward and forward motion to the upper and lower riddle shoes. These require looking to at least twice a day, likewise the wooden bearings of the straw shakers, which in cold weather, if not kept clear of dirt and grease, will soon work themselves warm. "A good lubricant is obtained by mixing about an ounce of graphite to a quart of oil, and for the hard wood blocks a mixture of 1 lb. of tallow to lb. of olive oil and 1 oz. of graphite, the mixture to be slightly warmed, and when |