As regards temporary outlets, wooden outlets if large (unless made of seasoned wood and therefore costly) are liable to give great trouble. Water escapes round the outside or through the joints. Pipes may do well if laid in puddle but are brittle and costly if of large size. The irrigators may interfere both with wooden outlets and pipes and they are liable to be displaced or broken. A temporary outlet, if small, can be made of bricks laid in mud. The joints can be pointed with lime mortar. When the outlet is made permanent the same bricks are used again. But all kinds of temporary outlets are liable to give trouble especially in light or sandy soil. There is much to be said in favour of building masonry outlets at the first, making a barrel only, _i.e._, omitting the head and tail walls and taking the chance of having to alter the size. The alteration is not very expensive. The head and tail walls are built when the size has been finally settled. The adjustment can be made by raising or lowering the roof. This should be done over the whole length of the outlet but lowering can be done temporarily over a length of 3 feet at the tail end of the outlet. This can be done even when the distributary is in flow. A reduction over a short length at the upstream end of a barrel does not, as already remarked, necessarily reduce the discharge much. On inundation canals the rules regarding outlets have to be modified. Great numbers of watercourses take off directly from the canals. In such cases, especially near the head of a canal, the ground to be watered is often 5 to 8 feet above the canal bed and it is wholly unsuitable to place the outlet at bed level. The cost of the tail wall would be excessive. The floor level in such cases must be at about the lowest probable cleared bed level of the watercourse, say, in order to be safe, a foot or half a foot below the usual cleared bed of the watercourse, so that water need never be prevented from entering the watercourse. The irrigators should be consulted as to the floor level and their wishes be attended to as far as possible. For lift outlets the floor should be at the bed level of the canal or distributary. If this bed is to be raised in the course of remodelling, the floor should be at the old bed level until the bed has actually been raised, unless there is a weir which raises the water. It is necessary that lift outlets should work however small the canal supply may be. In a distributary or small canal, the head wall should be built up to F.S. level but in a canal with deep water the head wall should reach up to just above the roof of the outlet and be submerged in high supplies. The stepping of the head wall should be set back if the channel is to be widened and should project into the channel if the channel is to be narrowed. The centre line of the channel near the outlet site must always be laid down and the outlet built at right angles to it and also at the correct distance from it.