118 REPORT—1848. 
‘the breadth of land to be drained, the proportion seldom being greater than 10 horses’ 
power to 1000 acres, and in some cases considerably less. 
The general plan is to carry away the water coming off the higher grounds, and 
prevent it, as much as possible, from running down into the marsh by means of the 
catch-water drains before mentioned, leaving only the rain which falls upon the district 
to be dealt with by mechanical power. 
As the quantity of rain falling on the Great Level of the fens seldom exceeds 26 
inches in the year, and about two-thirds of this quantity is carried off by evaporation 
and absorption or the growth of plants, it is only in extreme cases that 2 inches in 
depth require to be thrown off by the engines in any one month, which amounts to 
14 cubic feet of water upon every square yard of land, or 7260 feet to the acre. 
The standard and accepted measure of a horse’s power is 33,000 lbs, raised one 
foot high in a minute, or 3300 lbs, raised 10 feet high in the same time; and as a 
cubic foot of water weighs 625 lbs. and a gallon of water 10 lbs., so one horse’s power 
will raise and discharge, at a height of 10 feet, 330 gallons, or 52,4 cubic feet of 
water ina minute. Consequently this assumed excess of 7260 cubic feet of water 
falien upon an acve of land will be raised and discharged at an elevation of 10 feet in 
about two hours and twenty minutes. If the quantity of land be 1000 acres of fen or 
marsh, with the upland waters all banked out, the excess of rain, according to the - 
foregoing estimate, will amount to 726,000 cubic feet. A steam-engine of 10-horse 
power will throw off this water in 232 nours, or in less than 20 days, working 12 hours 
aday. This calculation has been found fully supported in practice. 
Although the rain due to any given month may fall in a few days, yet in such case 
much of it will be absorbed by the ground; and the drains must be made of snflicient 
capacity to receive and contain the rain as it falls; besides, in case of necessity, the 
engine may be made to work 20 hours a day instead of 12, until the danger be past. 
The main drains have generally been cut 7} feet deep and of width sufficient to 
give them the required capacity to contain the excess of rain, and to bring the water 
freely down to the engine. In some instances, where the districts are extensive and 
their length great, it has been found necessary to make them somewhat deeper. 
In all cases where it has been requisite to use steam power, Mr, Glynn has applied 
scoop-wheels to raise the water. These scoop-wheels somewhat resemble the under- 
shot wheel of a water-mill, but instead of being turned by the impulse of the water, 
they are used to lift it and are kept in motion by the steam-engine. ; 
The floats or ladle-boards of the wheels are made of wood and fitted to work in a 
trough or track of masonry ; they are generally made 5 feet in length, that is to say, 
they are immersed 5 feet deep in the water, and their width or horizental dimension 
varies from 20 inches to 5 feet, according to the power of the engines employed and 
the head of water to be overcome, The wheel-track at the lower end communicates 
with the main drain, and at the higher end with the river ; the water in the river being 
kept out by a pair of pointing doors, like the lock-gates of a canal, which close when ~ 
the engine ceases to work. The wheels themselves are made of cast-iron, formed in 
parts for convenience of transport. The float-boards are connected with the cast — 
iron part of the wheel by means of oak starts, which are stepped into sockets cast in the — 
circumference of the wheel to receive them. 
There are cast-iron toothed segments fitted to the wheel into which works a pinion 
fixed upon the crank-shaft of the steam-engine. When the head of water in the 
river or delivering drain does not vary much, it is sufficient to have one speed for the 
wheel; but where the tide rises in the river, it is desirable to have two speeds or 
powers of wheel-work, the one to be used at low water, the other more powerful 
combination to act against the rising tide. But in most cases it is not requisiteto 
raise the water more than 3 or 4 feet higher than the surface of the land intended to 
be drained, and even this is only necessary when the rivers are full between their 
banks, from a continuance of wet weather or from upland floods. 
In some instances the height of the water in the rivers being affected by the tide, 
the drainage by natural outfall can take place only during the ebb, and here, in case 
of long-continuing rains, the natural drainage requires the assistance of mechanical 
ower. 
i It has been stated that the main drains have generally been made 73 feet deep, or 
more in larger districts, so that the water may never rise higher than within 18 inches: 
