(k.) DUPLICATE ROPES. 108 miles of spare 4 inch rope, 221 tons, at 517. 6 miles of 5 inch head-rope for inclined planes, 19 tons, at 511. Interest on this amount at 51. per cent. per annum, being the annual cost of duplicates 974 2 O 400 7 0 1,572 O 0 550 0 0 £14,784 9 0 739 4 5 chief portion of this line descends gradually with the load, and in favourable weather the reciprocating system is adopted on one plane only. The data, therefore, afforded by this railway cannot apply to the Liverpool and Manchester, where the whole is supposed level, or nearly so. One instance, to which Mr. Walker refers in his report, as affording data on this 325 674 370 715 57 800 631 77% 750 704 89 780 942 101 1000 It is necessary to observe, that the gross weight taken at a time, in Nos. 1 to 6 is about 32 tons. The empty carriages, returning, being about one third of the gross weight. In Nos. 7, 8, 9, 10, 16, 17, 18, and 19, the quantity conveyed annually over the respective planes did not amount to more than one third of that which passed over the other planes. Where marked, C denotes that the plane is curved; and S that it is straight. NOTE R. Experiments detailed by Mr. James Walker, in a paper to the Royal Society, read May 31, 1827. The experiments were made in the middle of the East India Import Dock, 1410 feet in length, 560 feet wide, and 24 feet deep. A spring weighing machine was fixed near the bow of the boat, the dial laid horizontally; one end of a line inch in diameter, was attached to the hook of the spring; the other end was attached to a reel or barrel, 3 feet in diameter, the frame of which was firmly fixed in the ground, with handles of sufficient length for the necessary number of men to turn the barrel. The velocities were calculated while the boat was dragged this 176 yards; but to obtain uniform velocity, the boat was, at each experiment, drawn over twice the length, and the 176 yards taken in the middle of the distance by two marks upon the line; an exact uniformity of motion was obtained by means of a pendulum hung up in sight of the men who turned the barrel, by the oscillations of which they regulated the revolution of the handles. The experiments in Table A. were made in a full built boat, loaded with 2 tons 2 cwt., exclusive of the men; the length of the boat was 18 feet 6 inches; breadth, 6 feet; the depth of immersion, 2 feet; the whole depth of the boat being 3 feet, leaving 1 foot above water; the greatest immersed cross section, 9 feet. important point, is on a part of the Hetton railway, which is nearly level, where 301,800 tons are conveyed over 2 miles for an expense of 7801. in ropes, which gives, according to the most favourable mode of calculating, th of a penny per ton per mile. 100 This part of the Hetton road is worked by the reciprocating system to a greater extent than on the Brunton and Shields, and the planes not varying widely from a level, it gives better data than either of the others; yet it does not seem to have influenced Mr. Walker's conclusions on this point, having fixed on 8th of a penny per ton per mile, whereas the daily experience at Hetton indicates ths. Since, however, the curves which exist on that line may increase the wear of ropes in some degree, we shall take the cost, when applied to the Liverpool and Manchester, at 11th of a penny per ton per mile. The experiments in Table B. were made in the same boat, with about 2 tons of ballast. The experiments in Table C. were made in a boat 28 feet in length, but, being light and more exposed to the action of the wind, the smaller boat already described was preferred. "The average resistance of Nos. 7, 8, and 10 (low velocities) is 941 lbs. ; the corresponding velocity, 2,529 miles. The average resistance of Nos. 1 and 2 (high velocities) is 4,259 lbs., the velocity, 4,529 miles. The resistance calculated in the duplicate ratio of the velocities would be 38.11 lbs., in place of 42.59 lbs. Again, the same low velocities, Nos. 7, 8, and 9, compared with No. 3 (velocity 3.871), would give, by calculation, a resistance 22′04, while the actual resistance was 28.07." A few experiments were also made in a small Thames wherry, the distance 80 yards. The average velocity of four of these experiments was 106 yards per minute, or 3.60 miles per hour; resistance, 10 ̊4 lbs.; and of four others the velocity was 160 yards per minute, or 5.5 miles per hour, and the resistance 29 lbs., while the ratio of the square of the four preceding experiments would have given 24.27 lbs. The small excess in the large boat, compared with the smaller and the wherry, Mr. W. considers to have been owing to the form of the bow of the former boat causing less heaping of the water in the front, than in the latter. NOTE S. Section of the Durham and Sunderland Railway, from Whitwell Colliery to the shipping places on the river Wear, at Sunderland. Siding twenty chains on the moor, and further on to the staith, descends about one eighth of an inch per yard. LONDON: Printed by A. Spottiswoode, |
