Page:The American Cyclopædia (1879) Volume XIV.djvu/447

 KOPE BORIC FIGURES 427 machines are for forming the rope, and are placed in a horizontal position ; the others are for making strands and hearts, and are verti- cal. Wire hearts are used for bridge cables, &c. Hemp hearts are used instead of wire for standing rigging, as it makes the rope more pliable. The amount of twist to give to the strand and to the rope itself varies with the size, and requires much care and judgment on the part of the manufacturer. The numbers assigned to the various sizes of wires run from No. 22, the smallest, to No. 0, the largest. The heart of the strand must be of the same size as the single wire, and the heart of the rope the size of a strand. The softer hemp permits the inside wires to become imbedded, as in the preceding figure. The foregoing description of wire-rope making applies to the fine wire of 133 to a rope. A stiff er kind of. rope is made of coarser wire having seven to a strand and 49 to the rope. The sizing of the wire will be understood from the annexed diagram. "Wire rope is applicable to all the general purposes of ordinary rope, except running rigging on board ship, and has many advantages over that Wire Rope with Wire Heart. made of hemp or hide. Its first cost is less than that of hemp rope of equal strength, the only correct mode of comparison; and, as a general rule, it will last three times longer than hemp rope. Its utility and economy have been fully demonstrated on inclined planes and slopes, to which purposes its application has become very general, and for hoisting, in ware- houses, machine shops, founderies, mines, &c. It has also been substituted with perfect suc- cess for staying or guying derricks, suspension bridges, cranes, shears, masts, chimneys, &c., and for these purposes, not being affected by the weather, it never requires resetting, saving thereby a large amount of labor. For ferries, tow lines, tiller ropes, suspending gasometers, lightning conductors on vessels or houses, haul- ing logs in saw mills, for transmitting power to a distance in place of belting, and for all other purposes of this kind, where safety, durability, and economy are necessary, wire rope is far superior. Wire rope must not be coiled or uncoiled like hemp rope. When mounted on a reel, the latter should be turned on a spindle to pay off the rope. When in a coil without reel, roll it over the ground like a wheel, and run off the rope in that way. All untwisting or kinking must be avoided. To preserve wire rope, apply raw linseed oil with a piece of sheepskin, wool inside, or mix the oil with equal parts of Spanish brown or lampblack. To preserve wire rope under water or under ground, take mineral or vegetable tar, add a bushel of fresh slacked lime to a barrel of tar (to neutralize the acid), and boil it well, then saturate the rope with the boiling tar. The grooves of cast-iron pulleys and sheaves should be filled with well seasoned blocks of hard wood, set on end, to be renewed when worn out ; this end wood will save the rope and in- crease adhesion. The small pulleys or rollers which support the ropes on inclined planes should be constructed on the same plan. Steel wire is to a certain extent taking the place of iron wire in ropes, where it is a special object to combine lightness and strength. ROQUEPLAN, Joseph Etienne Camille, a French painter, born at Malleinort, near Aries, in 1803, died in Paris, Sept. 29, 1855. He became known in 1827 by his illustrations of Sir Walter Scott's romances. In 1853 his " Amateur Antiquary," painted in 1834, brought 30,000 francs. His latest and best painting was "The Well near the tall Fig Tree " (1852). RORIC FIGURES (Lat. ros, dew), a name ap- plied to certain curious images rendered mani- fest upon breathing on polished solid surfaces, when these have been previously exposed to contact with or close proximity of the objects thus represented, and usually at the same time acted upon by light, heat, or electricity. The singularity of these phenomena is, that they consist usually in the production at the first of a sort of latent or invisible image, which may afterward be developed somewhat in the manner of photography. Dr. J. W. Draper, in the " Philosophical Magazine " for September, 1840, mentioned certain facts going to show that an insensible molecular change may be made to take place in the surface of bodies ; and among them he named the following in- stance, as long known : " That if a piece of very cold clear glass, or, what is better, a cold polished metallic reflector, has a little object, such as a piece of metal, laid on it, and the surface be breathed over once, the object being then carefully removed, as often as you breathe on it again, a spectral image of it [the object] may be seen; and this phenomenon may be exhibited for many days after the first trial is made." Moser of Konigsberg first distinctly called attention to these figures ; his statement through M. Regnault to the French academy in July, 1842, being to the effect that generally,