I871j 



Heat. 



427 



that, with an initial pressure of 20 pounds or 25 pounds in a boiler, it would 

 give an effective pressure of 150 pounds on the pistons of the engine. 



Mr. J. Sutherland has described an ingenious modification of the common 

 suction pump, to be emp^ed for the pumping of hot liquids where there is 

 considerable difficulty in getting a sufficient flow of the liquid when its tem- 

 perature is at all near the boiling-point. This result, of course, arises from 

 the well-known fact that liquids boil at lower temperatures exactly as the 

 pressure on its surface is decreased. The pump itself was simply a steam 



Fig. 13. 



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W&ter jitiPfc, ^ 









f 







A 





Is 









t» ' * 



cylinder, having a set of ports opened and 

 closed by slide valves, and producing an ex- 

 haust by means both of the up and the down 

 stroke. This arrangement gave excellent re- 

 sults so long as the liquid was comparatively 

 cold, throwing a continuous stream 2^-inch 

 bore or about 10 to 12 tons spent-lye per hour. 

 The cause of failure was due to the exhaust 

 produced by the pump being as rapidly filled up 

 as formed by the vapours generated from the 

 liquid, brought to a state of ebullition by the 

 decreased pressure produced in the pump con- 

 nection. It then occurred to Mr. Sutherland, 

 that if he could introduce a fine spray of cold 

 water at the inlet of the pump it would con- 

 dense the troublesome vapour and allow the 

 pump to do its work. A water-pipe passed 

 along the wall within a foot or two of" the inlet, 

 and, between the two, a connection was opened 

 with a 4-inch lead pipe having a stop-cock to 

 regulate or shut off the water supply. The end 

 fitting into the cast-metal pipe was fitted with 

 a small rose, in order to spread the water on 

 entering. The accompanying sketch shows the arrangement. A is the 

 pump cylinder, b the steam cylinder, c a 3-inch inlet, d |-inch pipe introduced 

 on the upper, surface of the inlet pipe. It is imperative that it be introduced 

 on the upper surface of a horizontal pipe, as it is there the first vapour will 

 gather and be exposed to the condensing action of the spray. Were the cold 

 water introduced at the lower surface of the pipe it would mix with the hot 

 liquid, and, in all probability, its action would be almost nil. The application 

 proved a thorough cure, and not more than about Jth of an inch bore of water 

 was necessary to set the 3-inch inlet in full action. 



ELECTRICITY. 



At the meeting of the Royal Society of Edinburgh, held on the 29th May, 

 Dr. R. M. Ferguson described and exhibited a magneto-electric machine of the 

 following nature: — The revolving Siemens's armature consists of one piece of soft 

 iron, with two grooves cut in it, the one at right angles to the other, for the 

 reception of two coils of insulated wire, one of which, on the motion of the 

 armature, gives off a current to excite the electro-magnet, between whose poles 

 it rotates, and the other gives off an external current. It is in effect a modi- 

 fication of Ladd's ingenious application of Siemens's andWheatstone's prin- 

 ciple of magnetic and electric reciprocity, only instead of two armatures placed 

 in length and moving on the same axis, with their coils at right angles, a 

 single double coiled armature in this instance is employed. The grooves are 

 of unequal sizes, the larger being four times more capacious than the smaller, 

 and the larger coil, which furnishes the external current, has its wire twice as 

 long and twice as thick as the wire of the smaller coil and groove. The corn- 

 mutating collars at each end of the armature, against which the springs press, 

 can be moved round and fixed at any angle with the planes of the coils. The 

 core of the electro-magnet, made of boiler plate, is 11 inches long, g inches 

 high, and 6 inches between the sides, and the revolving armature within is 11 



