as fine as No. 120 are now spun on the ring spinning-frame, a machine invented in this country, and more used than any other for warp spinning, and now being adopted in Europe. Yarns as fine as 550 are spun on mules for three-cord sewingcotton, and for experiment much finer counts have been reached. It has often been alleged that fine yarns could not be as well spun in the United States as in England, owing to the dry and electrical conditions of the atmosphere during a considerable part of the year. This difficulty has existed in some degree, although not so as to preclude fine work if it had been profitable to undertake it; but, as far as this difficulty existed, it has lately been entirely removed by the invention of a very simple and inexpensive apparatus for moistening the air with the finest spray of pure cold water, by which method the air of a spinning or weaving room may be kept at any desired degree of humidity in the dryest day, so that the adverse effect of electricity is entirely overcome.

Whenever the condition and extension of our market will warrant the undertaking, there is now no obstacle, to our manufacturing any variety of cotton fabric that is in demand, either coarse or fine.

The following examples will give an adequate idea of the construction and general appearance of American cotton factories, and of the dwelling-places of the operatives:

[The completed work will be illustrated with steel engravings of several of our best mills.]

The following examples will give an adequate idea of the mode of construction of American cotton machinery and other apparatus connected with cotton mills, nearly all the diagrams being of machines that are in some respects peculiar to this country. [In the completed work diagrams and descriptions will be given of such machines as the following.]

The Kitson opener; Whitehead & Atherton lapper; Foss & Peavey card; Whitin Machine-shop card (self-stripper); Saco Water Power Company roving-frame; Sawyer ring spinningframe; Whitin ring spinning-frame; Fales & Jenks Manufacturing Company Rabbeth spinning-frame; Mason mule; Lowell slasher; Lewiston warper; Lyall loom (wide); Empire loom (fast); Knowles loom (fancy); Blake pump; Parmelee automatic sprinkler; Fales & Jenks Manufacturing Company rotary pump; Holyoke Machine-shop water-wheels; Garland moistener.

It is suggested that the complete work, of which this publication is a specimen, may be made more complete in the department of cotton and cotton manufacturing, if persons interested will communicate additional information or suggestion to the undersigned.

BOSTON, October, 1879.

E. A.

[From "The American Architect " of Sept. 20, 1879.]
THE VIBRATION OF MILL BUILDINGS.

TO THE EDITOR OF THE AMERICAN ARCHITECT.

BOSTON, September, 1879.

Dear Sir,-Assuming that a large factory or machine-shop is to be constructed upon the slow-burning principle, with open timbers, plank floors, deck roof, &c., there remain other points to be considered, which do not appear to have yet received sufficient attention from either the mill-engineer, the professional architect, or the builder. In many of the existing mills, even of apparently the best construction, there is a great tendency to vibration; and in some of the mills that are high and narrow, the vibration is very great. When it is considered that the lateral motion which constitutes this vibration has been imparted to the whole structure, and that it causes a pressure of every bearing in the mill, first on one side and then on the other, it will be obvious that a great deal of power must be wasted, not only to induce this motion, but also to overcome the additional friction caused by it, especially in heavy bearings.

If the common method of constructing a factory be considered, its faults may be apparent, and possibly the remedy. Assume an ordinary mill, 350 to 500 feet by 72 feet, four or five stories high, with towers to brace the centre only; throughout the greater part of the length the section showing two rows of posts and two side walls, with no brace whatever to prevent them from yielding or bending in some degree either way. There are mills within our knowledge in which a pail of water two-thirds full cannot be set upon the upper floor without slopping over; others in which gas-pendants will sway from side to side more than two inches. One mill was lately inspected, of unusually good construction, built of stone, with arched brick floors, four stories high, carrying very heavy machinery for working flax. On the first floor of the mill it was observed that the gas-pendants hung from the second floor had a very marked swing from side to side. We have the record of another large mill construction with iron beams, in which, before the machinery could be operated with

any success, it became necessary to put wooden beams under the iron, and to lift the iron from the brick walls so that all the bearings should come upon the wood.

This vibration has been attributed chiefly to the motion of the looms; and it is now customary to place looms across the mill, and not lengthwise, and also upon a lower floor, as far as possible. In some cases one-half the looms are operated at a little lower speed than the other half, in order to avoid a synchronous movement of the lathes; but there are many other causes of vibration, even in the rotary motions of other machines and of the shafting, pulleys, and belts. Wherever there is friction there is a cause of vibration; and when it is necessary to construct a mill or workshop above one story in height, a remedy must be sought in the method of construction.

Mill construction appears to have been considered more with reference to the support of dead weight than to stiffness or absence of vibration. In point of fact, the dead weight to be sustained in a cotton or woollen mill is very little. If we take as an example a mill of 32,000 cotton spindles on No. 24 yarn, the floor space and dead weight of the machinery, omitting openers and pickers, which would, almost as a matter of course, be placed upon a concrete floor in a separate building, would be substantially as follows:

COMPUTATION FOR A COTTON MILL OF 32,000 SPINDLES.

slashers; and, as the floor reserved around the slashers is used to pile loaded yarn-beams upon, the weight at this point is relatively much more than the figures show.

A mill floor constructed in the usual manner would consist of beams 12 by 14 inches in one or two parts, 8 feet on centres, 3-inch plank, 14-inch top floor. The material would usually be hard pine and spruce; this would be substantially equivalent to 6 inches of wood of uniform thickness. Spruce weighs 30 pounds per cubic foot; Georgia pine, 48 pounds. On these figures the floor described would be equal to 19 pounds weight to each superficial foot of floor surface. If -inch mortar were used between the floors, it would add about 6 pounds per square foot, making 25 pounds in all. The total weight of floor and load is, therefore, from 50 to 60 pounds per foot of surface in the principal departments of the mill. If the load be multiplied by 8, the standard of the beams would be to bear a breaking strain of 250 pounds per foot of surface, or 50,000 pounds on each beam 25 feet long, supporting 4 feet of floor on each side of the centre, 200 square feet per beam. (An actual weight equal to this was lately found in a warehouse used for storing cheese.) The weight of the floor itself would be distributed about in the proportion of 7 pounds in the beams, and 12 pounds in the plank and boards of the floor. These figures would be varied a little, according to the kind of timber and plank used. In a mill 72 feet wide in the clear, with two rows of posts, the beams must each be a little more than 24 feet long; and it is obvious that there must be a very great proportionate weight on the centre of each beam, and therefore a tendency to sag in the middle. What that means in respect to the adjustment of shafting, and the operation of machinery, every manufacturer knows to his cost and trouble.

How to stiffen the beams without exposing iron truss-rods, such as are commonly used, to the action of fire, as the combustion of the contents only of almost any room of a textile factory would heat truss-rods so as to make them useless, and would probably heat and destroy iron beams, - would seem to be a suitable question. The problem is, how to get the strength of iron and the slow burning of a heavy wooden beam. Objections are made by some engineers to composite beams of iron and wood; and it is not desirable to reduce the substance of the wood more than one-half, that is, not to have either of the two parts of a beam much thinner or more combustible than the floor.

It is alleged that the weight upon a floor sustained by a composite or "flitch" beam will rest either on the iron or on the wood, and cannot be brought upon both together. If your correspondents have any data upon this point, it would be interesting to the mill constructors to know them.

It has been suggested that a factory may be braced with inside rods; but it is desirable to avoid rods, because of their tendency to collect lint.

The equivalent of the knees used in the construction of a ship has been suggested; but it is desirable not to tie the beams to the walls, so as to prevent the ends rolling out of their bearings in case they break or burn one at a time.

Buttresses would doubtless serve a good purpose, but they are somewhat objectionable if deep enough to obstruct light in the lower stories.

Our problem therefore is, how to construct the walls, either solid or hollow; how to brace the posts; and how to construct the beams so as to give the utmost stiffness, and so as to avoid vibration.

There are problems not yet solved in respect to the construction of the frames of machinery as well as of the mills, that would perhaps repay scientific study with a view to avoiding vibration, -a familiar example of the unscientific use of material being the original use of stone sleepers on the Lowell Railroad.

The problem of rightly combining wood and metal in the framework of rapidly moving machinery, and wood, metal, brick, or stone in the construction of the factory, appears to offer a wide field for saving in power, friction, wear, and waste.

These points are stated as indicating some of the points that might be well considered by the student of industrial architecture, and every attempt at architectural effect must be absolutely subordinate to them. The only true effect that can be rightly aimed at must be that which gives expression to these considerations of safety and utility. E. A.

AMBROSE EASTMAN, ESQ., Secretary.

BOSTON, Dec. 15, 1879.

Dear Sir, -The official statement of the export of cotton fabrics for the fiscal year ending June 30, 1879, should be increased in the sum of about a million seven hundred thousand dollars, making that year the largest of record.

The change occurs because a correction of the figures compiled in the Bureau of Statistics in Washington has been made by a comparison with the import figures at Ottawa, Can.

This correction had been made at my suggestion, during previous years, but was overlooked this year. The attention of the authorities has been frequently called by the Chief of the Bureau of Statistics to the inadequacy of the export statement in respect to Canada.

Yours truly,

EDWARD ATKINSON.