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If the proportions are such that a circle drawn around the center A, with radius AD, falls outside the center B, as shown in the figure, we have what is known as a Whitworth quick return motion. Here the slotted crank makes one complete revolution for each complete revolution of AD, but its speed is not

WHITWORTH'S QUICK RETURN.

uniform. In this figure, a connecting rod PT is represented as attached to a point

P on the slotted link. The other end of this connecting rod moves the tool holder T along the straight line BT. When the linkage is in the position shown, T is in its extreme right-hand position, and it will be in its extreme left-hand position when BP occupies the position BP,. In turning BP through this angle (180°) AD has turned through the angle L. In returning BP to its right-hand position again, AD has to turn through the angle M only. Now, since AD turns with uniform speed and since angle M is less. than angle L, T makes its stroke from left to right in less time than was required to move from right to left. The time of advance and time of return are in the ratio of angles L and M. If the length of the crank AD and the ratio of time of advance to return are known the distance AB may be found as follows:

With A as a center and AD as a radius, draw a circle and divide the circumference by the points D and D, so that angle L may bear the same ratio to angle M that the time of advance bears to the time of return. Join D and D, and from A draw a line perpendicular to DD1, meeting it at B, which will be the required center for the driven crank.

The distance BP governs the length of the stroke of the tool, so that by varying the position of P the length of the stroke may be varied.

Small Cement Block Plant

Will you please give me some idea as to the equipment for a small cement block plant?— A. L. B.

In the equipment of a cement block plant a shed is necessary about 30 by 70 feet, with a wing on the north side, preferably in the middle. The shed shouid face the west and east, with windows only on the north. This to prevent any of the sun's rays from striking the green blocks inside. A track should run through the center of the shed for a car to convey the blocks from the west end during the morning, and from the east end during the afternoon.

The wing should be large enough for a sand bin, a cement room and the machines. It should be two stories in height, and on the second floor should be placed a cement hopper, with a spout leading down to the mixer below. The cement hopper should be of sufficient size, so that it will be necessary to fill it not more frequently than three times a day. Unless the mixer has an automatic feed, the cement should be measured into the spout to suit the batch. If it has an automatic feed, the cement of course may run through the spout continually.

A sectional rack of five or six tiers should be installed in the shed. When there are several machines in operation, a car system may be used, and the racks will not be necessary. For convenience, elevators may be installed to convey the material to the hoppers.

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three-way snap switches. Throw-over knife switches may be substituted for these three-way snap switches if de/ sired.

Determining Size of Hydraulic Ram

Kindly tell me what measurements determine the size of a hydraulic ram.-W. D. W. In order to select a ram of suitable size, the following data must be obtained and

SUPPLY

DIAGRAM OF AN HYDRAULIC RAM.

measurements made as shown in the sketch:

1st. Quantity of water, in gallons per minute available for supply.

2nd. Quantity of water, in gallons, required at discharge in 24 hours.

3rd. Vertical fall in feet, from supply to proposed location of ram (A).

4th. Distance from supply to ram (B).

5th. Vertical distance from ram to point of discharge (C).

6th. Required length of discharge pipe from ram (D).

Treating Scaled Boiler

What would be the best method of treating a badly scaled boiler, that was to be cleaned by a liberal use of compound?—A. L. W.

First open the boiler up and note where the loose scale, if any, has lodged. Wash out thoroughly and put in the required amount of compound. While the boiler is in service, open the blow-off valve for a few seconds, two or three times a day, to be assured that it does not become stopped up with scale.

After running the boiler for a week. shut it down, and, when the pressure is down and the boiler cooled off, run the

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set of resistances like the Wheatstone bridge, except that two of the resistances (R1 and R) are inductive rather than ohmic resistances.

A galvanometer, G, is put in circuit with a key, k2, across the bridge, and is connected with the galvanometer commutator. In the same way the battery is connected across the other two points of the bridge, and to the battery commutator, which is immediately in front of and on the same shaft with the gal

vanometer commutator.

With the shaft stationary, balance up the bridge with L, as the induction to be measured; L, is a known standard induction resistance. Then, from the law of the Wheatstone bridge

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Propeller Pump

Please explain the action of the propeller pump.-F. P. A.

The basic principle of the propeller pump is that the water is lifted by screws somewhat similar to propeller screws, termed "runners," each consisting of two half circular inclined blades fastened to a shaft at intervals of 5 feet and of still less diameter than the casing.

In one form of the propeller pump known as the "Woods," there is a boxing for the shaft placed immediately underneath each of the runners. The boxing is held in position by a set of spring blades, termed "guides," set lengthwise of and engaging the well-casing, and thereby held firmly in position, and so arranged as to interrupt the whirling motion imparted to the water as it is thrown upward by the runners, and to turn the water back in the opposite direction, and thereby deliver it into the revolving blades of the runners in a direction opposite to that in which the runners are rotating. By this method the whirling motion of the water is utilized and the capacity of the pump largely increased without any increase of power.

With this pump water may be raised from several hundred feet below the surface by extending the shaft and runners down the well-casing the desired depth; it being necessary, however, to always have the lower runner submerged in water. Then as the shaft is rotated the lower runner lifts the water up to the runner above it, and that one to the next, and so on until the water is delivered to the surface, or above the surface if desired, the distance depending upon the size and pitch of the runners, the number of runners and the speed at which they

are run.

No increase of speed is required for additional depth, because more runners are added as the depth is increased; and this compounding of the runners increases the efficiency of the pump, for whatever number of pounds pressure is exerted on the water by one runner in lifting it at a given rate of speed is repeated by each of the runners. For example, if one runner running at a given rate of speed, gives ten pounds pressure per square inch, then two runners would give 20 pounds; three, 30 pounds, etc.

Duties of Surveyor's Helpers What are the duties and requirements of the axeman, chainman, and rodman in a surveying party?-A. C. B.

The duties of an axeman are to prepare, drive and mark stakes; to cut brush, fell and blaze trees, and keep the line clear for sighting and chaining as directed. He must cut points on stones, assist in setting up instruments, in chaining and running the rod. He must carry tools, keep them in good condition, and be generally useful.

The duties and requirements of the chainman are:

To run the chain, read it and keep tally of the chain lengths. He should know the sources of error in his work and avoid them as much as possible; he directs the axeman in clearing lines for chaining, and the stakeman in driving stakes, assists in carrying instruments and acts as rodman when required.

The duties and requirements of a rod

man are:

To "run" the rod, take readings and keep record of same as a check upon the leveler's notes.

To select and fix turning points and bench marks.

To act as chainman, set and mark stakes, etc.

To set up instruments.

To take the place of the leveler in the latter's absence.

To assist in carrying instruments, tools. In calculations, office work, etc.

He should be familiar with the principle of leveling, and understand the sources of error in his work. He should known the rudiments of trigonometry, be able to use logarithms and assist in earthwork and other calculations.

To Prevent Steam Leaking

Where the piston rod of a locomotive passes through the back head of the cylinder, how is the steam prevented from leaking?-D. S. H.

The rod passes through a stuffing-box and the space between it and the box is filled with an elastic material like hemprubber and cotton; this material being pressed against the walls of the stuffing-box and the outside of the rod by the box cover. A tube which projects inside the box presses against the box and the rod. There are also split

packing-rings of anti-friction metal which are pressed against the rod and the box by springs.

Method of Setting Valves

How can I set the valves on a single cylinder, 4-cycle gas engine?—A. L.

Make a mark on the surface of the cylinder, and with the cylinder head off, turn the engine over, holding a rod fast against the end of the piston and determine the exact point at which the piston is at the end of the stroke. To do this make a mark on the rod and turn the en

gine over several times to see that the mark on the rod is in the same position each time at the end of the stroke.

With the piston exactly on center, take a tram as shown in the accompanying figure, and with a point at x scratch a circle on the face of the flywheel and make another mark at y. Note the exact distance between the points of the tram, and at a suitable time you can find when the end of the piston is at the end of the stroke without taking off the cylinder head. To determine the point when the piston is at the opposite end of the stroke, mark a line from the point y past the center z of the crankshaft. It is best to mark the maIchine when first received from the factory, say with a point m showing the time of closing of the inlet valve, and a point 1 showing the time of opening of the haust valve.

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A good way to determine just when the cam puts a thrust on the valve stem is to slip a thin

X

TO SET VALVES ON A GAS ENGINE.

piece of paper under the stem and turn the engine over, until the paper is gripped. The point of release of the valve can be determined by finding when the paper is released. When the igniter lead is constant another point

should be marked on the flywheel showing the time when the spark occurs.

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And Still They Come!

AMONG the most prominent families in Hartford, Connecticut, is one which President Roosevelt would certainly never censure for "race suicide." The size of this family has always been a standing joke in Hartford. Mark Twain himself, although a devoted friend of the family, has not scrupled to poke fun at it.

It is related that, when a certain pastor of Hartford, who had just been raised to a bishopric, was making his last pastoral calls before entering upon his new duties, he visited

the mother of the family in question. After a brief conversation, during which some reference was made to the "children," the good man rose to go. "You haven't seen my last baby, have you, doctor?" asked the mother.

"No, madam," answered the divine, with a smile, "and I may say that I never expect to." Success.

False Logic ATTORNEY-GENERAL MOODY, discussing a legal point, said:

"That is striking but false logic. It reminds me of a conversation I once heard at the seashore.

"A man in a striped bathing suit was running on thin, pale legs over the hot, white beach toward the cool water when a friend, seizing him by the arm, said:

"'What! Are you going in to bathe just after a heavy lunch? Why, you will be drowned.'

"Oh, no; not at all,' replied the other. 'I ate nothing but fish.'"-Philadelphia Bulletin.

An Optimist

A GEORGIA man lost a leg in an accident, and when they picked him up the first words he said were: "Thank the Lord, it was the leg with the rheumatism in it!"-Atlanta Constitution.

The Test Supreme

"IS HE a thoroughly honest man?"

"I don't know," answered the man from Missouri. "I have trusted him with hundreds of thousands of dollars, but I never tried him with a book or an umbrella."-Washington Star.

Why Norah was Worried

My maid Norah went to consult a fortuneteller and returned wailing dismally.

"Did she predict some great trouble?" I asked sympathetically.

"Och, mem, sich therrible news!" moaned Norah, rocking back and forth wringing her hands.

"Tell me," I said, wishing to comfort the girl.

"She tould me thot me father wurks hard shovelin' coal an' tindin' foires fer a livin'." "But that's no disgrace nor sorrow," I said, a trifle vexed at such affectation.

"Och, mem, me poor father!" sobbed Norah. "He's bin dead these noine years!"-Judge.

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