Parallel bars

“ But to traverse the head carrying the tools along the bar necessitates a feed screw either within the bar or outside of it. If within, the metal removed to give it place weakens the bar, while in small holes there is no room for it; hence solid bars with fixed cutting tools are used for small holes, and tools held in a traversing head for those sufficiently large to give room for a head without weakening the bar too much. A boring bar is best driven from both ends. ”

“ The stress within the bar is shearing stress, consisting, as it must, of two sets of equal tangential tractions on two sets of planes which are at right angles to each other. These planes are the cross-sections and the axial planes of the bar. The tangential traction at any point of the cross-section is directed at right angles to the axial plane through the point, and the tangential traction on the axial plane is directed parallel to the length of the bar. ”

“ It is, therefore, always preferable to bore and tap the ends of such bars, and to screw in a wrought-iron or steel plug, taking care to screw it in very tightly, so that it shall not at any time become loose. The centres should be well drilled and of a comparatively large size, so as to have surface enough to suffer little from wear, and to well sustain the weight of the bar. ”

“ Many ingenious devices for forming bars have been produced; but generally a strong frame is used, across which steel wires are stretched at distances equal to the size of the bars to be made, the blocks being first cut into slabs and then into bars. ”

“ It must not be supposed that he makes a law of this procedure, but the remarkably frequent occurrence of so curious a device is certainly suggestive of conscious purpose in structural treatment. The result of this mode is that the movements often appear to be crowded with ideas. Commonly the features of the opening bars, which in modern times would be held of almost supreme importance, serve for very little except to determine the character of the movement, and often never make their appearance again. ”

“ The bar (C) is divided into three parts, corresponding to the long, medium, and short provincial lines, insulated from each other, and connected respectively with the bars of the relays (V, V', V") through the galvanometers (g, g', g", Fig. 8) . ”

“ To one set of vertical bars a similar number of horizontal top pieces are hinged, and to the other set levers are jointed, which hold the horizontal bars in position. When the hinged bars are turned up, strings are drawn through the grooves, and the bottom is covered with stout paper. The hanks are then laid in the box, another paper is placed above them, and the hinged bars are drawn down and locked. ”

“ Each bar which they make being inflexible by a feathered rib, is rendered perfectly straight in its edge by grinding with emery upon a flat disc-wheel of block tin, and of invariable length, by a most ingenious method of turning each set of bars in a lathe. The bars are afterwards adjusted in the metallic sieve-frame, or chest, at any desired distance apart, from the 120th to the 60th of an inch, in such a manner as secures them from all risk of derangement by the vibratory or jogging motion in shaking the pulpy fibres through the lineal intervals between them. ”

“ Thus, for instance, the impact caused by putting a key down should have the effect of driving a small weight upwards in the direction of a metal bar, the distance of which can be adjusted. Another bar, at a lower level, is also approached by a second weight, and the perfect degree of evenness in the touch is indicated by the fact [Pg 258] that the lower bar should be made to emit a faint sound with every note, but the higher one not at all. The closer the bars the more difficult is the exercise, and remarkable evenness of touch can be acquired by a progressive training with such an instrument. ”

“ If a boring bar is to be used only for work that does not require facing at the ends, the cutter, slot, or keyway should be placed in such position in the length of the bar as will best suit the work (keeping in mind the desirability of having the bar as short as possible) , and the bar should be tapering from the middle towards each end, as shown in Fig. 1130. This will make the bar stronger in proportion to its weight, and better able to resist the pressure of the cut and the tendency to deflect. ”

“ It is composed of three graduated bars, one of which is held over a fulcrum and carries the others, which are lighter, one at each extremity. The three bars are movable from end to end in box-sockets, each having an index and a vernier in contact with the graduated scale. The box-socket of the principal bar turns round the vertical axle of the fulcrum; that of each side bar is attached to a vertical axle, which also carries a grooved wheel of large diameter and turns in a collar at either end of the principal bar. ”

“ We recal to the recollection of our readers the observation which we have before made, that the destruction of the bars not only leads to contraction by removing a powerful impediment to it, but by adding a still more powerful cause in the slanting direction which is given to the bearing at the heels, when the bar does not contribute to the support of the weight. ”

“ Each bar is struck by a mallet or mallets, and motion is communicated to the arms of the mallets by cords or other suitable attachments to the outer end of the arms, and passing down the tower or other place where the bars are fitted. ”

“ Nor is there any essential difference between the apparatus of Fig. 38 and that of Fig. 20. In Fig. 38 the bar is pulled down by a force at each end, one a weight, the other a spring balance, while it is supported by the upward pressure of the steel edge. In Fig. 20 the bar is being pulled upwards by a force at each end, and downwards by the weight. The two cases are substantially the same. In each of them we find a bar acted upon by a pair of parallel forces applied at its extremities, and retained in equilibrium by a third force. ”

“ Long Figures, on the other hand, occupy a strain of eight bars in long measure—a strain being that part of an air which is terminated by a double bar, and usually consists in country dances of four, eight, or sixteen single bars. ”

“ Rotate the bar by hand, and if the tool just touches the work without taking a cut the line of centres is parallel with the ways. If there is space between the tool point and the turned end of the bar, the tailstock requires setting over towards the back of the lathe, while if the tool takes a cut the tailstock requires to be set over towards the operator. If a bar is at hand that is known to be true, a pointed tool may be adjusted to just make a mark on the end of the bar when the slide rest is traversed. ”

“ At each end of each bed of bars it is expedient to leave a space which the ashes cannot fill up so as to cause the bars to jam; and care must be taken that the heels of the bars do not come against any of the furnace bearers, whereby the room left at the end of the bars to permit the expansion would be rendered of no avail. ”

“ Naturally they pulled the bar of iron although separated by two heavy layers of wood, as there is no insulation which will stop magnetic waves, thus closing or opening the door at the will of the operator. The poker and the heavy overstuffed chair were caused to travel about the room in the same manner, the latter probably having iron bars inserted in the legs, by utilizing other electro-magnets fastened beneath the floor and concealed by this plasterboard. ”

“ There are three thick bars, each set stoutly in woodwork nearly as hard as iron itself, and we want to do this work so carefully that it will not be noticeable should anyone enter the room. Each bar will have to be loosened both top and bottom, and I know not how long it will take us. We will work as constantly as we can, and I doubt not in time we shall be free as the birds, as far as this window is concerned. ”

“ A second hasp, similarly constructed, secures the lowest of the three bars; but, as that bar is behind, and not in front of, the shelf to which it belongs, the arrangements described above are reversed. One lock and key serves for the ironwork belonging to the three shelves.
Fig. 76. Iron bar and socket, closed to prevent removal of the bar: Hereford.
The chains are made of links of hammered iron as shewn in the sketch (fig. 78) which represents a piece of one of the actual size. There is usually a swivel in the centre, probably to prevent twisting. ”

“ Four bars extend outward from an upright post placed in the middle of the floor, and a large flat stone is fastened to the end of each bar by means of a rope. A horse is hitched to one of the bars, which is purposely left longer than the others. ”

“ The performer now places the bar to the extreme points of his fingers, and holds his arm in a horizontal position, when the bar is again seen suspended without any support in that most difficult position.
To prove that this wonderful performance is done without the aid of invisible silk, wire, wax, or mechanism, the operator places the bar against the back of his hand, and once more it is seen suspended in mid-air, while he takes it quite close to the company for inspection. Price, $2. ”

“ Beneath the circular plate forming the support or frame of the watch-movement the gang of steel bars or springs is firmly attached to the plate in such position that the points are in a straight line radial to the centre, and over each point is a hole in the plate so that each can be pushed upward, the point thereof passing through the hole sufficiently to perforate the paper dial in the space corresponding to the point of the spring. ”

“ The common form of the smaller sizes of boring bar is that shown in Fig. 1127. a a being the bar, d d the lathe centres, b the cutter passing through a slot or keyway in the bar, and c a key tapered (as is also the back edge of the cutter) to wedge or fasten the cutter to the bar. It is obvious that, if the cutter is turned up in the bar, and is of the exact size of the hole to be bored, it will require to stand true in the bar, and will therefore be able to cut on both ends, in which case the work may be fed up to it twice as fast as though only one edge were performing duty. ”

“ This bar (Fig. 2) , for its simplicity, portability, and strength, has a reputation for being one of the most useful kinds of apparatus made. Not only is it used for a bar, but children’s swings, hand-rings, and trapeze can be attached to it, as the supports can be spread out to allow the bar to stand at various heights by shifting the stretcher irons (A A) up and down. These irons, three-eighths of a inch in diameter, are cranked at each end—i.e., bent at right-angles—and fit into holes in the uprights about 3 inches apart. ”

“ The mode of upsetting, widening, and shaping the ends of the bars is by placing the ends, after the bars have been rolled into proper shape and size, and the ends heated, into a die-box of the regular form, and then firmly locking them in place, and with great power pressing them up endwise with a movable head-die until the hot iron fills the die-box. ”

“ SORRENTO BARS (No. 8) . These are bars which occur most frequently in Italian lace. They are simply twisted threads, so closely entwined that they only appear as one. They also are frequently radiated, and crossed; the effect produced will be seen in the accompanying diagram.
DOTTED VENETIAN BARS (No. 9) . A bar of threads is made, as for a common Venetian bar. Do on it six stitches, and instead of drawing the seventh tight, hold the top by sticking a needle through it and the paper, about the tenth of an inch, and work on the threads of the loop three button-hole stitches. ”

“ It is with me a clear point that the table moves when the parties, though they strongly wish it, do not intend, and do not believe that they move it by ordinary mechanical power. They say, the table draws their hands; that it moves first, and they have to follow it,—that sometimes it even moves from under their hands. With some the table will move to the right or left according as they wish or will it, —with others the direction of the first motion is uncertain:—but all agree that the table moves the hands and not the hands the table. ”

“ Bars should be transversed and flat, not less than one-and-a-half inches in length and a half-inch in width. Studs shall be round in plan, not less than half-and-inch in diameter, and in no case conical or pointed. ”

“ This board is fixed with wax exactly in the centre of the lower part of the press—the table. By "exactly in the centre" it is to be understood that the centre of the various blocks brought together lies on or near the centre of the draw-out plate. If there are more and heavier blocks fixed to the upper than to the lower side of the plate, the latter must be lowered a little—in a word, the plate must be so adjusted that all parts receive equal pressure. It is only by making a few trials that one can learn exactly what is right. ”

“ In another game a bar, twelve to fourteen feet in length, is balanced by means of a point in a socket on an upright reaching about four feet and-a-half above the ground. Over the end of the horizontal bar a boy hangs, and, touching the ground with the feet, spins himself round. ”

“ Fig. 3 is a working drawing of a corner, dimensioned as suggested. It will make clearer the directions. It is fundamental that the spacing be done in the same direction on parallel rails, for at times [Pg 10] the last space will be a short 1⁄2 in. or whatever dimension is used. In such cases it is necessary to redivide the last several spaces into divisions as near 1⁄2 in. as possible. It thus becomes obvious why spacing must be done in one direction as stated. This applies to all rectangular frames.
FIG. 3. SKETCH OF CORNER FOR CANING. ”