Engineering Wonders of the World
Volume I

EARLY ATLANTIC CABLES. 291 dition to another year, was equivalent to a loss of £100,000, which required to be made good. New capital was not readily obtainable. The projectors found it hard to stem a rising tide of popular distrust. Moreover, the sec- tion of the public who scouted the idea of an Atlantic telegraph had always been in excess of those who believed in it. But the de- pression which set in at the untimely ter- mination of the first expedition did not interfere with renewed and vigorous efforts to prepare for a second, the projectors being made of stout stuff, and in the end the appeal to the shareholders for more money met with a noble response. The directors were then enabled to arrange for the manufacture of 700 miles of new cable to replace what had been lost, and to provide a surplus against all contingencies. Thus, 3,000 nautical miles in all were shipped this time, instead of 2,500 miles. New paying-out gear was devised and con- structed with a view to obviating a1 recurrence of the accident that had ended the first expedition. In the new apparatus the brake (see Fig. 13) was so arranged that a lever exercised a uniform holding power in exact proportion to the weight attached to it (see illustra- tion page 292) ; and while capable of being released by a hand-wheel, it could not be tightened. The general idea of this clever appliance had been originally introduced by Mr. J. G. Appold in connection with the crank apparatus in jails ; and it was how specially adapted to the exigencies of cable work by the engineer (Mr. Bright) in conjunction with Mr. C. E. Amos of Easton and Amos, the firm which constructed the entire machinery. (Fig. 14.) By this apparatus only a maximum, agreed, strain could be applied, this being regulated from time to time by weights, according to the depth of water and consequent weight of cable paid out. The action of the gear is as follows :—In passing from the hold to the stern of the laying vessel, the cable is taken round a drum or drums. Io the shaft of each, of the drums A and B is a wheel fitted with an iron friction Fig. 13.—DIAGRAM TO SHOW PRINCIPLE OF SELF- RELEASING BRAKE. The two ends of the brake strap are attached by links C and D to a lever, pivoted at one end, and having regulating weights suspended from the other. A decrease of speed and increase of friction tends to revolve the blocks in an anti- clockwise direction, and to raise the wéight. As B is further from the pivot than is A, the brake strap is slackened, and the speed of the drum allowed to increase. The piston in the dash-pot has a small hole in it, through which the liquid has to pass wben the piston moves. This prevents too sudden movements of the weight. strap (to which are fixed blocks of hard wood) capable of exerting a given retarding power, varying with the weights hung on to the lever N, which tightens the strap. When the friction becomes great the wheels have an increased tendency to carry the wooden blocks round with them ; thus, the lever bars are deflected from the vertical line, and the iron band is opened sufficiently to lessen the brake power. Bright also introduced a much, improved dynamometer apparatus for indicating and controlling the strain during paying - out.