In a river, the rises and falls at different places are not, of coarse, the same, even when they are long continued. In the river Chenab, at the railway bridge at Shershah, the rise from low water to high flood is generally a foot or two more than the rise at a point 25 miles upstream. It has been suggested that the railway embankments, which run across the flooded area, cause a heading up of the stream. If this were the case, to any appreciable extent, there would be a “rapid” through the bridge, which, if it did not destroy the bridge, would at least be visible and audible. The exaggerated ideas which often prevail regarding the tendency of a river, when in flood, to scour out a new channel, have been mentioned in CHAP. IV., _Art. 8_. Spring, in his paper on river control, admits, when mentioning Dera Ghazi Khan, that there was little danger, but in mentioning the Chenab Bridge at Shershah he quotes, without disputing it, an opinion of the opposite kind (_Government of India Technical Paper_, No. 153, “River Training and Control on the Guide Bank System”). For some other fallacies, see _Hydraulics_, CHAP. VII., _Arts. 9_ and _15_. APPENDIX B =Pitching and Bed Protection= (CHAP. VI., _Art. 3_, and CHAP. X., _Art. 2_).--Any scour upstream of a weir is merely due to the eddies formed upstream of the crest (_Hydraulics_, CHAP. II., _Art. 7_), and is not serious. And, similarly, as to scour upstream of a pier. A hole formed alongside a pier or obstruction, if there is no floor, may work upstream. The chief use of a floor extending far upstream is to flatten the hydraulic gradient (CHAP. X., _Art. 3_). For pitching of the sides, monolithic concrete is not very suitable, because it may settle unequally and crack. For heavy pitching, concrete blocks can be used. They can rest on a layer of 3 to 6 inches of rammed ballast or gravel. The toe wall, as shown in fig. 13, page 65, is sometimes dispensed with, the pitching being merely continued to a suitable depth below the bed, and the bottom edge being at right angles to the slope instead of horizontal. The portion below the bed may be of concrete. INDEX Abrupt changes in streams, 28. Alterations in a channel, upstream effect, 4. Aqueduct, Kali Nadi, 149. Available rainfall, 9. Bank protection, 60. -- -- artificial weeds, 70. -- -- berms, 70. -- -- bushing, 68. -- -- fascining, 66. -- -- heavy stone pitching with apron, 71. -- -- on the Adige, 67. -- -- reinforced concrete, 70. -- -- rolls of wire-netting, 70, 140. -- -- staking, 69. -- -- trees, 68. -- -- twig revetment, 68. -- -- Villa system, 69. Banks, 92. -- Bell’s guide, 137. -- continuous lining of, 64. -- dimensions of, 93. -- guide, 137. -- side slopes of, 92. Barrage of the Nile, Assiut, 117. Bars, river, 203. Bed, protection of, 58. -- -- Villa system, 59. Bell’s guide banks, 137. Bends, effect of, 44. -- short cuts of, 44.