Although these areas of vibration are modified by the columns and walls, yet they are not coincident with any divisions of the floor, because excessive vibration has been observed near such places, while the portions away from such support were at rest; but the reverse is generally the case, and the most perfect repose is near the points of greatest stability, where one would naturally expect to find it.

The superintendent of a New Hampshire mill, when in the factory on Sunday, was greatly surprised at the shaking of the building. He observed that the water was flowing in broken sheets over the dam, and presumed that the pulsations of air were synchronous with the key-note of the mill; continuing his observations, he learned that with a greater or smaller flow of water over the dam, the mill was at rest; and also, with the scuttle in the roof open, so that the puffs of outside air were in free communication with the interior of the mill, the vibration was much greater than when the scuttle was closed.

At Centredale, R.I., the water flowing over the dam caused at times a great vibration in the mill. This has been stopped by fastening vertical pieces of plank, at intervals of ten feet, against the front of the dam, and projecting upwards so as to break the long sheet of water into numerous short falls, whose key-note was different from that of the whole sheet of water which they displaced.

At the Essex Woollen Co., mill number eight is sometimes. thrown into vibration by the water flowing over the dam; and, when this happens, the watchman on duty alters the note of the dam by opening the waste-gate, and the mill soon comes to Mill number five of the same company, but at a privilege lower down the stream, is often thrown into vibration by the falling water at that point; and the story is told, that a watchman once fled from that mill, thinking that it was about to fall.

rest.

Of the eleven mills owned by this corporation, I have been told that none of the others vibrate from the above cause. When in operation, mill number six was often thrown into vibration by the motion of the machinery.

When vibrations are due to machinery, they are stopped by changing the speed.

At the Merrimac Mills, Lowell, and many other places, this method has been successful. It is unnecessary to cite further examples; but in all cases vibrations are noticed when some

adequate cause is sounding the key-note: if the velocity of these pulsations is altered, the vibrations due to that identical cause will cease.

The consequences of mill vibration, in the power absorbed by its exertion, in the continual straining of machinery and mill, must inevitably tend to damaging results to plant and product.

Were not a lot of columns placed almost at random out of the question in a mill, we could make the statement that vibration could be diminished and nearly stopped by placing columns under the principal centres of vibration, and so divide the floor into still smaller areas of vibration.

The only sure method of prevention applicable to the future seems to lie in the construction of one-story mills, with the shafting resting upon piers in the basement. The result in the additional speed without any disturbance of stability, and of the diminution of the repairs under the same excessive conditions in mills constructed upon the one-story plan, will hasten their introduction. In such a mill, if vibration should take place, it could be stopped by additional columns in the low basement without interfering with the machinery.

The swaying of a mill owing to oscillation is due to a lack of stability, and weak construction; and the only correction possible for such cases is to increase the strength by reconstruction of weak portions of the building.

Mr. GARSED. While we are on the subject of one-story mills, I must tell a story of my own. In 1853 we built a onestory mill in Philadelphia. It was sixty-six feet on the inside, and five hundred feet long. We built it upon the ground. We did not put any posts under it, or any basement. We simply went along in a democratic manner, and built a mill, and put blocks of stone, and set machinery on the blocks of stone, as there was no basement. It was set on the earth. We did not have any vibration, of course, and we have not to-day. I got up to give you the exact facts. For twenty-six years that mill has been running; and to-day there is no vibration from the machinery, except that which is in the machinery itself. An unbalanced cylinder or an unbalanced pulley will make a frame vibrate, I don't care what frame it is. But the drawback to a one-story mill in our climate appears to be the objection of work-people to walk upon stone, whether it is from the damp

ness or the rigidity. But I would build a one-story mill again, only I would make the walks of wood. I would put the machinery upon stone, but would never run the risk again to get spinners to work upon a stone floor; though it is a very common thing to do in England.

Mr. ATKINSON. This asphalt flooring is a non-conductor of heat, and therefore will remedy all that difficulty.

Mr. GARSED. But there seems to be a want of elasticity to it where people are walking over it all day in a very warm building. I don't know why it is so; but I have made up my mind that I will never again undertake to have a stone floor in any mill in America. If you make a concrete floor, and sink boards one inch below the top of the concrete, and, when the floor rots out, pick up these pieces, and substitute a new one, you will have no difficulty. If your mill is built upon the ground, put your machinery upon blocks of stone, with a piece of leather between the foot of the machinery and the stone, or a piece of sheet-lead. There will be no danger of vibration of the mill, and none whatever of its burning down. But I must say that our experience has not justified the conclusion that it does not take any more heat in winter, and that it is as cool in summer as any other. It does take more heat in winter, and we find it uncomfortably warm in summer.

Mr. ATKINSON. How thick is the wood of the roof?

Mr. GARSED. It is plain inch planks, covered with felting and white gravel.

Mr. ATKINSON.

That marks the difference between a oneinch and a three-inch roofing-plank. The three-inch plank for the roof will keep the one-story mill warm in winter and cool in summer, and will prevent the condensation of moisture on the inside. In Mr. Johnston's weaving-room, he screws his looms right down into this asphalt material.

Mr. GARSED. We bore a hole into the stone, fill with lead, and put an ordinary wood screw into it, the same as you would upon a floor.

Mr. BIRKENHEAD. In Mr. Cumnock's remarks as to the effect of want of balanced pulleys, if he had taken a piece of chalk, and held it near the face of said pulley, he would have noticed the mark left by the chalk would indicate two things worthy of knowing: first, the exact location of the heavy side of the pulley; second, the wear on the shaft in the bearing nearest the pulley,

which, if run a long time, would wear the journal to a form between that of the letters O and D: what is generally known as a flat place; but this convex coincides with the circle of the bearing which is formed by the frictional contact to the circle of the bearing. It is very clear, if the heavy side is always in a line or opposite to the face of this wear, or, in other words, the excess of weight on the pulley, and wear on the shaft, both are on same side, this being the case, the excess of weight must be the cause of the wear. If it is, let us see how this wear takes place. In the first place, the heavy side is the controlling power: the energy of this power is directed outwards, multiplied by its weight and velocity, as it were; the force keeping one side of the shaft constantly in frictional contact with the inner surface of the bearing, instead of a natural revolving contact, there results a sort of scraping or eccentric motion. Now, it will be seen from this, there is no ground for the old idea of hard and soft places in metal, which seems to be an accepted belief by many; the law being a natural one, hence a positive one, results in producing a flattened surface. There is iron that contains hard and soft places, but not in a form that causes a shaft to wear out of round, by any means; for when this is seen in iron it has the appearance of a piece of corduroy, or a fluted roll, or the grain of wood. Lowmoor, and other fine grades of iron, are free from such. Hard and soft places are sometimes found in machinery-steel, caused, I should say, by want of carbon in the soft places. Tool steel contains more carbon, hence is not so liable to have soft places. Spindlesteel contains an excess of carbon above tool or machinery steel. There seems to be no limit to the amount of carbon which steel will take. The Mushet steel, for instance, is harder than hardened steel without the chilling process. In speaking of the uneven wear of shafts, you, no doubt, have noticed flat places on spindles, illustrating the same fact. The causes are these if the bolster-bearing is flat-sided, the spindle top or blade is bent, or imperfectly straightened, producing a heavy side on the side of the flattening surface. If the quill is out of balance, it will have an eccentric motion, the same as an imperfect spindle, but is not likely to form a flat place, for the reason that the quill is being constantly changed in doffing, otherwise a flat place would result. Having thus explained the cause of wear in the bolster-bearing; the flat place in the

foot or step-bearing is caused when the butt is out of balance, through an excess of weight on one side of the extreme cone or V point of the foot, as the point is its balancing centre; and when an eccentric motion is produced becomes worn still more towards the light side, causing the heavy side to become still heavier. You will naturally infer after this statement, or ask the question, Why does not the band keep it up to a bearing? To this I would say, it has no more power to do so than a belt on a shaft, when the pulley is out of balance; for the throw is so great, the band, with a pull of four or more pounds pressure, has no control over it. What is called a vibration in a spindle is not an indiscriminate rattling about, as it appears; any more than a shaft rattles about. It is a rapid, eccentric motion, uniform in its action. It has an artificial centre, and revolves around it. It requires skill to make a good spindle. It makes but little difference how or where you support a spindle; if it is out of balance its life is short, whether light or heavy, or whether it is hard or soft; the result will be the same, if it is out of balance. The law of eccentricity will destroy it, support it where you will; you may stop its appearance, but not its effect.

This has been my experience in the matter for years, and I have endeavored to improve the mode of making spindles, so that inferior work will be less liable to be made. Permit me to suggest here the survival of the fittest. I leave you to decide. I think the time has come for you to ask whose spindle has survived. To speak for myself, I say I have not received an order for, neither have I made, a spindle to replace a worn-out one, nor have I repaired one, since I commenced to make light spindles.

Mr. GOULDING. It occurred to me while the discussion was going on, that those who were paying for coal to make steam to move machinery had enough to do to furnish to run the machinery, without furnishing power to shake the mill and heavy arches. We ought to impress this lesson on our minds, that machinery should be so built as not to have to furnish sufficient power to vibrate the whole building. No one can deny that we have it. We can most of us tell what it is that causes the shaking. Mills may be so placed that it is almost inevitable that the mill should shake from the motion of the looms. Suggestion has been made to put in more posts or timbers. That is