tioned, which support the pipe carriers, because they are actually subjected to the strain on the pipe or wire line when the leverman moves his lever. Nothing is more vexatious than to have one or more of these foundations move after an interlocking plant is completed, and if there is any doubt as to the solidity of the ground it is best to stand on the safe side and be sure to make them large enough.

I have found the following sizes to be a good average, but as before stated if the ground is marshy or very light they had better be made larger. For cranks: 26 in. wide, 26 in. long and 3 ft. deep. For compensators: 26 in. wide, 52 in. long and 3 ft. deep.

For deflecting bars, 24 in. x 24 in. x 3 ft.

For radial arms and chain wheels: 24 in. x 24 in. x 3 ft.

On account of their size it is not convenient to ship them around; and the quite general practice is to dig a hole of the proper dimensions, suspend the crank, compensator or whatever device is to be set, in its proper position over the hole, and fill in with concrete. In sandy, loose soils, it is frequently necessary to make forms to reach to the bottom of the hole, but in stiff soils a form around the top to give that part of the foundation which shows above ground a neat appearance is all that is necessary. It is very important that the bottom of the hole be kept level, so that the concrete will set with a flat base. If the sides are allowed to cave into the hole, the concrete foundation or block is apt to be made with a rounded bottom, and is then more likely to rock when a strain is put on the pipe line than it would be if it stood on a flat base.

The cranks, compensators, etc., are secured to the concrete block in one of three ways:

(1) By being bolted to blocks of oak through which and extending out from their lower side, are 4 34-in. hook bolts long enough to reach nearly to the bottom of the concrete, which is filled in around these hook bolts.

(2) The same as above, except that the oak block is omitted and the upper ends of the hook bolts are passed through the base of the device to be fastened down.

(3) By using cast iron legs or piers, the tops of which are grooved so as to take the head of a short 34 in. bolt slipped in from the end of the groove. The thread end of the bolt is passed

Fig. 39.

through the base of the device and the nut then put on and screwed down. Two of these piers are used for each device.

Fig. 39 shows a crank fastened to its foundation in each of the three ways.

The first method is little practiced now. tendency is to do away with the use of wood as much as possible at interlocking plants.

The second method allows of no sidewise adjustment in case the foundation should move, which is unavoidable at times on new fills.

The third method is excellent practice, although

if the nuts loosen the bolt heads may slide along the grooves and allow the device to move sidewise when it should not. It cannot move far, however, and may easily be driven back into place, and the bolts tightened up.

The tops of all foundations should be neatly finished off with grout. It is generally a sign of a good foreman if he takes pains to leave his foundations looking well.

CHAPTER VII.

LOCKING AND OPERATING DEVICES.

Our next step brings us to the operation of

switches.

The simplest way to do this, of course, is to let the pipe line which is to operate the switch run along side of and parallel to the track in which the switch is, and when reaching a point opposite the head rod of the switch, to set a crank and connect its arms, one to the pipe line leading from the machine and the other to the head rod of the switch. To a certain extent this is the method followed. However, it would not be safe to depend on this alone, as the switch might be 600 or 700 ft. away from the machine and entirely out of sight of the leverman, and as the pins, jaws, crank arms, etc., are wearing all the time, enough lost motion is soon made in the pipe line to prevent the leverman detecting the presence of some hard substance like a stone between the switch point and the stock rail, which might spring the switch point enough open to cause a derailment.

The most approved method of operating a switch is as follows: The pipe line is led up to the head rod just as described. The lever which operates a switch gives the pipe line a movement of 834 ins. which is carried up to the last crank arm. As the throw of switches is not often over 5 ins. we want to lose 334 ins. of stroke between the crank and the switch point. We could, of course, shorten one crank arm, but the better method is by using what

is known as a special switch adjustment. This is an arrangement of a threaded rod fitted with nuts passing through a socket. If the nuts are closed up on the ends of the socket any movement imparted to the rod will move the socket, but if the nuts are moved away from the ends of the socket any amount of motion we please, less than the motion of the rod, will be imparted to the socket. In practice the nuts are followed by jamb nuts which prevent their backing away after being once set, and the socket is fastened to the head rod of the switch.

Fig. 40 shows a very popular form of this device.

CB

Fig. 40.

This is intended to be attached to the head rod between the two points of the switch.

In addition to the special switch adjustment attached to the head rod of the switch, a front rod is attached to the points. This front rod which is shown in Fig. 41 is made up of three parts; (1) the rod itself, (2) the right hand point lug, (3) the left hand point lug.

L.H. Point Lug

R.H Point Lug

Lug.

Fig. 41.

The point lugs are bolted to the switch points so as to extend a little beyond their ends, and the rod is attached to each of them so that as the switch is moved from one of its positions to the other, the front rod is given a longitudinal movement equal to the throw of