— 142 Description of Units and Results of Tests.

In general, the tabulated results are self-explanatory. By water horse-power is meant : Gallons per minute X weight per gallon x head in feet -r 33,000.

The costs are given in local currency : 1,000 milliemes =£E.l Egyptian = £1 Os. 6d. sterling.

The areas irrigated are given in feddans : 1 feddan = 1-06 acres.

Plant No. 1. Central Research Farm.

This pumping unit was one of the earliest used for irrigating the farm lands, the total area served being about 250 feddans. It was situated on the banks of the main Nile, about 4| miles below Khartoum.

The plant contained one vertical Cochran boiler, furnishing steam to a tandem compound vertical engine fitted with enclosed forced lubrication.

The pump was directly coupled to the engine shaft by flange couplings, and was of the centrifugal type, having suction and delivery pipes of 12-inch diameter.

The rise and fall of the river at flood season is very considerable, the variation in the lift being as much as 20 feet, and to obviate the necessity of lifting and lowering the engine and pump with the rise and fall of the river, they were placed in a watertight building and erected at low river level. By the adoption of this method the pump was submerged at high flood, while a short suction was permanently ensured when thfe river had fallen to its lowest level.

The boiler was installed in a separate building above flood level, and was supplied with feed water by an injector and a duplex pump, both delivering from a feed heater. This engine was originally fitted with a jet condenser, but serious defects finally necessitated the scrapping of the condensing gear.

The first trial was run on August 25th, 1912, to determine the fuel consumption, and unfortunately did not permit the separate determination of engine and pump efficiencies. The lift was low, being only 8- 3 feet, consequently the plant was running much below full speed, which resulted in considerable loss of efficiency.

The figure 269 (feed water per W.H.P. per hour) shows the combined performance of engine and pump, and is abnormally high, a result due partly to the inclusion of steam used by the feed pump which was by no means economical, and partly to loss of efficiency caused by the low speed.

The conclusion arrived at for this excessive consumption of steam was that it was due either to badly-fitting piston valves or to leaky pistons. As the