called a lantern gland, whose construction is plainly shown in the drawings, figures 5, 6, and 7. The larger part of the packing is placed above the lantern gland and the remainder below it, and the lantern gland, being free to slide along the rod as the gland proper is screwed up, communicates the pressure applied to the packing below it to the larger mass of packing above it. There is a drain pipe communicating with the hollow space of the lantern gland, for carrying off any water which is carried into it by the piston rod.

FIG. 13.

This drain pipe is so located relative to the lantern gland that, notwithstanding the latter's movement along the rod, it always remains in communication with the hollow spaces within it. The operation of this combination of parts is as follows: The water which follows the piston rod through the upper portion of the packing is received by the lantern gland from which the most of it passes off through the drain pipe, the portion of the water which is in that part of the lantern gland below the drain pipe being without pressure upon it does not find its way through the lower wart of the packing but remains in the gland and acts as a lubricant to the piston rod. The details of the cross head presents some constructive novelties; the

cross head block is a forked forging of wrought iron, which, instead of being bored "taper" for the reception of the conical end of the piston rod, is bored cylindrical, and the end of the rod is turned to fit it, and in order to preserve all the strength possible and provide a proper shoulder for the piston rod, a fine screw thread is cnt upon it just above the cross head block on which is run a gun metal nut (as is shown in figure 5), which receives the downward thrust of the rod, its upward pull being sustained by a steel key passing through the cross head block and piston rod below the nut. This construction admits of a larger cross section of solid metal in the piston rod adjacent to the lower edge of the key than is usually given, and at the same time simplifies the workmanship required. The fork of the cross head block is bored at right angles to the piston rod, and through it is passed the cross head pin secured against rotation by two small keys: the extremities of this pin are turned cylindrical and are fitted, but not fastened, in cylindrical

K

holes in the slide blocks; these are provided with "brasses," the working brass being adjusted for wear by a wedge bolt and nut, the wedge being pinched by a side set screw; both the working brass and its fellow are precisely alike, and when the working brass is nearly worn out it can be shifted to the other side of the slide block, a "liner" of proper thickness being made to take the place of that which secured the unworn brass in place: this "liner,” as will be seen in the drawing, is planed into both the brass and the body of the slide block, and is prevented from dropping out by a small transverse pin, by removing which both liner and brass can readily be displaced without disturbing the body of the slide block, and the working brass can also be easily removed by unscrewing the adjusting nut on the wedge bolt and letting the wedge drop through the bottom of the brass. The lower ends of the "brasses" are provided with inclined holes, which, as these ends dip at every stroke of the engine into the oil cup at the bottom of the guides, carry up oil enough for their lubrication.

FIG. 14.

The pressure of the steam upon the back of the slide valve is

partially removed by an automatically packed balance ring, the invention of William B. Robinson who patented it in 1864, he being at the time the mechanical engineer of the firm of Jackson & Wiley of Detroit, Michigan. Speaking from my own experience in the use of this invention on a large number of engines, I will say

that it deserves to be much more widely known and generally used than it has hitherto been;-it does not pretend to be a perfect balance, that is, to relieve the valve of all the pressure upon it, but by its use the objectionable steam pressure is very materially reduced. In fact, in my own practice I have found it convenient so to proportion the balance ring, that sixty per cent. of the pressure of steam was removed from the back of the valve when both steam

ports were closed. The construction of this balance ring is very simple ;—the steam chest cover is planed off on its under side, but the body of the slide valve does not quite touch this surface. On the back of the valve is a circular groove which is truly turned; in this groove is placed a compound ring made of cast-iron. This ring consists of an outer member of L section inclosing an inner member of rectangular section, as is plainly shown in the section of the valve in Fig. 5. The two members of the compound ring are cut transversely into the same number of segments and are so located with respect to each other as to break joints (see Fig. 12). This compound ring is supported by a number of spiral springs of brass wire which are strong enough to sustain the weight of the ring in contact with, but without exerting of themselves an undue pressure upon the steam chest cover, their object being simply to keep the ring from dropping away from the cover when the steam is shut off. When the engine is in motion the steam acts upon the under and outer side of this compound ring pressing it into steam tight contact with the planed surface of the steam chest cover, and the smaller circumference of the turned groove in the back of the valve within which the ring is placed, thus preventing all access of steam to the space inclosed by the ring. In order to ascertain whether the ring is acting as it should, it has been my custom to put a common try cock in the centre of the steam chest cover, which cock is always left open and any leakage of the ring is at once manifested by the escape of steam from this open cock.

In case of any undue accumulation of water in the cylinder the valve will leave its seat with even greater ease than the ordinary unbalanced valve. The dead weight of the slide valve is balanced by a counter weight on that arm of the rocker shaft which is coupled to the excentric. The stuffing box of the valve stem is constructed in a similiar manner to that of the steam cylinder already described.

I will now call your attention to the most prominent peculiarity of the construction of this engine; the mechanism for balancing the dead weight of those reciprocating parts connected to the main piston. The piston rod is secured to the piston by two gun metal nuts, the rod where it passes through the piston being enlarged as shown in the drawings; above these nuts the piston rod is prolonged of the same diameter as it is below the piston, and passes through a stuffing box in the upper cover of the cylinder and then enters a small cylinder in which it has attached to its upper extremity a small piston. The stuffing box just named is of a very