854 



HYDRAULIC MACHINERY, FOR MINES 



Pipes and Joints. For underground mains wrought-iron pipes pitched inside will 

 be found advantageous, since they will bo found to resist the action of ordinary water, 

 and can be bent cold to suit the course of a level. The ends should be fitted with 

 thick cast-iron flanges, the latter faced and formed as shown in^. 1186. 



1186 



The joints should be made with a ring of gutta-percha from ^ths to \ of an inch 

 diameter, unless the main is to be charged with hot water, when it will be better to 

 employ vulcanised rubber. 



Pumping Engines. Considerable attention has been given to the construction of 

 pressure-engines by Mr. Darlington, who was actively engaged some years since in 

 effecting the drainage of the Alport mines, in Derbyshire. 



The first engine erected by him had a cylinder 50 inches diameter, and a stroke of 

 10 feet ; the piston-rod passed through the bottom of the cylinder and formed a con- 

 tinuation with the pump-rod, whilst the valve and cataract gearing was worked by a 

 rod connected with the top of the piston, which gave motion to a beam and plug-rod 

 gearing. The column of water was 132 feet high, affording a pressure on the piston 

 of about 58 pounds per square inch, or more than 50 tons on its area. The water 

 was raised from a depth of 22 fathoms, by means of a plunger 42 inches diameter, 

 and in very wet seasons it discharged into the adit nearly 5,000 gallons of water per 

 minute. Water was admitted only on the under side of the piston, and in order to 

 avoid violent concussion in working, two sets of valves were employed, the larger 

 being cylindrically shaped, 22 inches diameter, and the smaller 5 inches diameter. 

 In making the upstroke of the engine the cylindrical valves admitted a full flow 

 of water for about ths of the stroke, and then commenced closing, but at this stage 

 the small valve opened, through which passed sufficient water to terminate the stroke. 

 In this way the flow of water in the column was gradually slackened, and finally 

 brought to a state of rest without imparting impact to the machinery. The speed of 

 the engine was regulated by sluice- valves, one fixed between the engine and the 

 pressure-column, and the other upon the discharge-pipe. 



The cylindrical valves were made of brass with a thin feather-edged beat, and kept 

 tight by a concentric boss, projecting from the nozzle, upon which hemp packing was 

 laid. This was pressed down by a projection in the under surface of tho valvo 

 bonnet. The water thus acted on the exterior of the valves between tho zone of 

 packing and the seatings, and when opened passed through tho latter. Besides this 



