be made in six segments instead of two, and if they are well put together, can be run at any practicable speed without the slightest danger of rupture.

The extra cost is more than compensated by absolute safety.

No driving pulley should have a velocity of more than 75 feet per second, the point of rupture being with the ordinary casting a little more than 300 feet per second; this allows for a factor of safety 4, as far as vibrations and shocks from rapid speed are concerned, and according to rules above quoted, as relates to tensile strength or rupture, a factor guiding the construction of fly wheels and large pulleys little enough, all must admit; but there are old pulleys running to-day at the rate of 60 feet per second, and are consequently dangerous in the extreme.

DISENGAGING VALVE MOTIONS AND THEIR

ADJUSTMENT.

When Mr. Corliss first adopted a regular standard of style or pattern for his horizontal engine cut-off gear, somewhere about the year 1853, he fixed on a plan superior in many respects to the standard now used by him.

Then there were no pieces of the detail of valve work attached in any way to the steam cylinder, save the four small connecting rods leading from trip motion to valve-stem arms.

All of the cut-off motion was fastened to the main bed-plate or frame, at a point nearly central with its length, and well away from the heating and expanding influences of the cylinder; and as the latch-block catches on barely more than one-eighth of an inch, it will be readily seen that all parts have very little leeway for disarrangement from the cause mentioned.

But the old plan has been discarded, and now every part connected with valve gear is attached to the cylinder, and is, of course, subject to all the changes by temperature common to the locality. Adjust this motion when engine is cold as perfectly as any valve setting can be, then start the engine, and, after an hour's running, take a diagram from each end, and they will show anything but proper setting; the conditions having been changed by the simple matter of expansion of metals. So it is absolutely necessary to make a final adjustment of this motion after the engine reaches its working temperature.

The exhaust valves of a Corliss engine seldom have lap and travel enough to give compression suited or required for high piston speed. These builders have their reasons for so doing, of course, which we certainly shall not question.

While the Wright engine (Newburgh), and the Brown engine (Fitchburg), both have their cutoff gear entirely assembled at the lower part of cylinder, they are not affected like the Corliss,

as one has no wrist-plate, and the other, though a plate is used, has it so far removed from heat, and so short in connections, that no trouble is experienced on this point.

The exhaust valves of a Brown engine are operated by the best method ever introduced for this purpose. They are worked by a cam which throws the valve wide open just before the beginning of the return stroke, and there the valve remains until within a short distance of the finish of the return, when it closes as suddenly as it opened. To give the required amount of compression, the lingering of the valve is accomplished by a concentric spot on the cam. We have seen these engines running at very high speeds, and never saw over one pound uniform back pressure registered by the indicator.

There is one very important thing overlooked many times in adjusting and setting trip cut-off gear. This is the matter of ascertaining if the eccentric rod (whenever it is used) is the proper length. Simply because an eccentric rod grasps a wrist-plate instead of a valve-stem is no reason for failing to attend to this prime-mover. When a competent engineer prepares to set a plain slide. valve, he first squares the motion and fixes the length of the rod exactly; he is then ready for the final touches. The leading motion for all detachable gear worked by an eccentric must have the same attention and correction of errors.

As for steam lead, we do not believe in it beyond of an inch. A valve motion too lazy in 31⁄2 its movement to open a valve without wire-drawing is entirely unfit for use in these days, and we are happy to say that the kind just designated as lazy are very limited.

Our American automatic valve motions are all bordering a little on the complicated order, but they are so well made that this fault is lost sight of.

GOVERNORS AND THEIR SPEED.

The steam engine governor has, we believe, received its share of consideration by engineers, especially in this country. To say that our American mechanics have produced an absolutely perfect working instrument in the regulating line, would be putting it rather strongly; but when we claim that we make the best governors for steam engines of all kinds, we have the statement in its true and just form.

No English power carpet-weaving establishment ever had steady and economical speed until the American model and proportion of regulator was attached to their engines. The English plan generally has been to speed the governor lower than the engine. I would like to see them driving carpet looms on this principle. American engineers rarely speed engines in the manner just described, most of them driving the gover

nor at the same speed as the crank shaft. The engines coming to our notice that regulate the best, are those furnished with governors speeded from 50 to 70 per cent. higher than the engine.

There are many patent high speed governors on the fly-ball, spring and water principle, all graded to run from three to six times the speed of crank shaft. But these, whether attached to their own special valves or to a detaching valve gear, fail to give the best results where the speed must be retained within one or two per cent. of the standard required.

An engine making 80 revolutions per minute, driving the class of machinery noted above, cannot vary more than one and one-half turns per minute without causing a damage to the fabric in weave room. There are engines performing this service to complete satisfaction, but they are not regulated by the extreme high speed governors. As a high speed governor, we believe the "Porter" to be as near perfection as it is possible to attain; it is certainly constructed on scientific principles, and is less subject to a trouble we shall speak of further on, than any other regulator of quick motion.

SINGLE AND DOUBLE HORIZONTAL ENGINES, AND THE TRANSMISSION OF POWER TO MAIN LINES AND COUNTER.

A wide diversity of opinion among experts