31

EXAMPLE, THE ROADWAY UPON CHAINS.

If the ascent be taken 1 in 8 * at Fig. 2 & 3 .the points of suspension, then <p = 7° 10'and -j— 8.0156, and 2 w be taken at 1175- (342-46.9 f) = 879.9, then w = 439.95and 8.0156k> — 3526.5. Now instead ofcables, if chain bars, as proposed bythe author in his design, be used, thenthe strength will be 61 X 192 = 12001200 : 16 : : 3526.5 : 47, and there willbe required only 47 bars of iron, each

* “ On the Welsh portion of the great road fromHolyhead through North Wales to Shrewsbury, theinclinations were formerly, in many instances, as muchas 1 in 6, 7, 8, 9,10.” See page 54., Report, Highways,June 25th, 1819. If 1 in 6 mean 1 perpendicular to 6ascending, then

1 in 6 = 9°,,35'; 1 in 7 = 8°,,13'; 1 in 8 = 7°,,10'; 1 in9 = 6°„23'; 1 in 10 = 5°„44'.

f 46.9 tons are deducted from the weight of the sus-pended road for the platform which will be wanted inboth cases.