Frequent attempts have been made to use peat as raw material for the manufacture of artificial wood. The material must, for this purpose, be fully reduced to a fibrous condition, so as to produce a mealy mass. This mixture is mixed with an emulsion of plaster and! water, and is subjected for considerable time to heavy hydraulic pressure in molds, then artificially dried, polished and oiled, painted or varnished.
Another process, says the. "Industrial World " .is to-wash the peat without destroying its natural fibrous state, and to mix the resulting moist mass with a mixture of hydrated lime and an aluminum compound and press it in molds for a short time in the moist state, after which the resulting plates are allowed to harden in the air. The resultant product needs only a. comparatively low pressure, and this for a short time only, and is then set out to dry in the air. The artifi-cial wood thus produced is not hygroscopic, and in order to use it for open-air work needs no painting or further impregnation. .
Copper becomes soft and malleable when strongly heated and immersed in cold water, its behavior under these circumstances being diametrically opposite to steel.
through and has a binding post on the top. The whole is provided with a thread for screwing into the cylinder head. The other point f is pivoted, its spindle running through the walls of the cylinder and being moved by the igoiter gear on the outside. Fig. 24 shows the outside gear in which I is a lever on the outer end of the spindle connected to the movable point f; and R is a rod guided by the guides GG. This rod is reciprocated by the same eccentric which operates the water pump, the eccentric strap being pivoted at E. On this rod is a stationary collar carrying the tappet t and the movable collar c. The screw a is in line with the outer end of the tappet t.
In operation the collar c is forced down against the lever I by the spring s pressing the lever and separating the sparking points. When the rod R ascends, the tappet t strikes the collar c and raises it out of contact with the lever I. The spring s then raises the lever I and brings the sparking point Into contact, allowing the passage of the current. As the rod R rises still further and arrives nearly at the top of its stroke, the screw a strikes the outer end of the tappet t, throwing this end down and the upper end out, and allowing the collar c to snap off and descend rapidly. Forced by the spring, this collar then strikes the lever I and forces it down quickly, breaking the contact in the cylinder and causing the spark. As the rod R descends, the tappet t snaps over the collar c and is ready for the next stroke.
The contact is thus broken suddenly; the more suddenly the break, the better and more effective is the resulting spark. By turning the screw a up or down it may be made to strike the tappet t sooner or later, thus changing the time of ignition. An engine having this particular gear is shown in Fig. 9.
It will be noted that there are two rods attached to a projection on the vertical rod; the outer one is the eccentric rod and the inner leads down to and operates the water pump. This illustrates the principle of the make and break ignition, namely, that the points are brought together at some time on the up stroke, held together for the passage of the current, and then snapped apart suddenly at the proper time. The
points should not, of course, be held in contact longer than necessary, as this would cause unnecessary waste of battery. The mere separation of the points is not sufficient, as they must be snapped apart quickly. The collar c does this by its hammer action. The adjustment of the sparking points to the type of gear is a nice matter, as the pin p must be screwed down to the proper point by trial.
The spark points require to be cleaned at intervals, which is done by unscrewing and removing the entire upper construction. The lower point can thus be cleaned through the hole, and the upper part be cleaned and replaced.
Another type of sparking gear is given in Fig. 26, such as is fitted to the engine shown in Fig. 10, the right hand view being a side view of the other. As will be noted, both points are on a sort of plug which is bolted on to the side of the cylinder by the bolts B B, allowing the points to project inside the cylinder. The point a is insulated from the metal of the plug hy a mica bushing or sleeve. The rod c, which can revolve, has on its inner end the strips of metal, or flipper f, which makes the contact with the point a when the rod c is turned. In this case the whole combination may be removed for cleaning by taking out the bolts li B, without in any way disturbing the adjustment of the sparking points.
The outer end of the rod a has a binding screw for fastening the wire. On the outer end of the rod c are the two small levers d and e. The lever e is fast upon the rod; the lever d is loose and may turn, but is always held down against a by a coiled spring, the other end of which is attached to the rod c.
The rod B is given an up and down motion by the eccentric whose strap is attached at O. The upper end of the rod is slotted to admit the tappet t which is pivoted as shown- A coiled spring s forces the tappet out into position. In operation, the rod -R is raised by the eccentric and the tappet t strikes the lever d and raises it. By means of the coiled spring before mentioned, the lever e and the rod c are turned, bringing the points inside the cylinder into contact. The position at this time is shown by Fig. 27.
The lever e can only rise a short distance owing to f striking the other spark point; the lever J is, however, raised higher, separating the two as shown and compressing the outside spring. As the rod B rises still higher the set screw s strikes the tail of the tappet t, forcing it in and drawing in the upper end. This allows the lever a to snap off; it descends with considerable force owing to the action of the coiled spring and, striking the lever a forces it down, quickly separating the sparking points. This illustrates the action of the "hammer break."
On the down stroke of the rod B, the tappet t is pressed into the slot by striking the end of lever d, and is forced out into place again by the spring s. By varying the position of the screw s it may be made to strike the tail of the tappet t earlier or later, thus regulating the time of ignition. The rod B is extended below and works the water pump, as shown in Fig. 10. The two gears just described are used on two cycle engines as they are driven from the main shaft and ignite on each revolution. A similar gear may be used on a four cycle engine, being driven from the valve or half time shaft, in which case the points are sometimes placed as shown in Fig. 28.
A very simple gear is shown in Figs. 29 and 30. It is in some respects similar to the preceding one, both points being on one plate. On the end of the rod c, Fig. 29, is the lever I, having at its outer end a hole through which the rod B passes. The coiled spring s is connected to a pin in the lever I, and tends always to keep the points separate. The rod B, Fig. 30, passes through the hole in the end of the lever I, and is encircled by a coiled spring whose upper end bears against the lever J, holding the head h of the rod B down against the lever l.. On the end of the valve shaft is the cam k, having a step, as shown. The lower end of the rod B rests upon this cam. In operation the cam k turns toward the left, raising the rod B, the pressure of the spring s also raising the lever I, bringing the sparking points into contact. The lever I then remains stationary and the rod B continues to rise, separating the head h considerably from the lever I. When the cam has turned sufficiently, the rod drops off the step, and is forced down by its own weight and the spring s; the head h strikes the lever I a sharp blow and carries it down with it, separating the points. The time of ignition is varied by moving the lower end of the rod R to the left, causing it to drop off earlier or later. This gear will only operate in one direction;
The cam k is, however, provided with a ratchet arrangement to prevent damage when the engine is turned in the opposite direction to that in which it runs.
These examples will illustrate the principles of action. A successful ignition should have the following qualities: viz., it should separate the points quickly, as the strength of the spark depends upon this; it should be simple, with as few parts as possible; some means should be provided for changing the time of ignition while the engine is running, as the best point of ignition is likely to vary for different speeds; it should be easy to clean and keep in order; the sparking points should preferably be tipped with platinum or similar metal, as steel points are worn away rapidly and soon become fouled.