The line should now be levelled, careful checks being made, a longitudinal section of it prepared and the proposed bed, bank and F.S. level shown. The ground levels ascertained by levelling the line, are certain to disagree, to some extent, with the contour lines. The latter were got only by inference from the levels of points in the survey lines, and they should be corrected in accordance with the fresh levels now available. If the line does not seem to be the best that can be got, a fresh line can be marked on the plan and the above procedure repeated. 8. =Final Line and Estimate.=--As soon as the best line seems to have been found, a large scale plan of the country along its course should be made by taking bearings or off-sets from points in it to the various objects and noting where the line cuts them. On this plan will be shown the exact alignment, the curves being put in and the straight portions slightly shifted where necessary so that the line may pass at a proper distance from any buildings or other objects. But before this procedure is carried out, or while it is being carried out, the estimate for the work can be prepared from the longitudinal section already taken. Such a section is of course amply sufficient for a “project estimate,” in which only approximate figures are given, and it is quite near enough for any estimate. In the case of small works which have often to be executed with great promptitude, lamentable delays have occurred owing to the engineer deferring the preparation of his estimate till he had got the line exactly fixed. Moreover there is a chance of the labour being thrown away in case the sanctioning authority directs any change in the alignment to be made. In the case of a large scheme, a project estimate is prepared. In this the earthwork and the area of land to be occupied are calculated pretty accurately. Designs and estimates are also prepared for the headworks and for the chief regulators. For works of which there are to be many of one type--bridges, falls, distributary heads and small drainage syphons--the cost is arrived at from lump sum figures, one drawing of each kind being submitted as a type. The distributaries are approximately estimated at mileage rates. In the case of a small scheme everything is estimated in detail except perhaps the distributaries or some of them. [Illustration: CANAL WITH BRIDGE AND DISTRIBUTARY HEAD. The Head has Gates and Winches. _To face p. 61._]