226 beport— 1879. 



I pursued the investigation further by producing artificial irregularities 

 in the pipe, and I then found the more completely I could throw the 

 water clear of the sides of the pipe, the greater effect it produced in ex- 

 pelling the air and starting the siphon. The form of siphon which I 

 have finally adopted as most effective is shown in fig. 3, and in the 

 working model. 



The siphon consists of two concentric tubes, A and B, the outer one, A, 

 being closed at the top, and steadied and supported by three radial ribs 

 projecting from the inner tube, B. The annular space between A and B 

 constitutes the ascending or shorter leg of the siphon, and the inner tube, 

 B, the descending or longer leg. At the upper mouth of B is fixed a conical 

 shell, c, projecting inwards clear from the inner surface of the tube, B. 

 The lower mouth of B dips into a discharging trough, d, which has a weir, 

 E, level with this lower mouth. The action is as follows : — When the 

 vessel is full, the water begins to trickle over the edge of the conical shell, 

 c, and is so directed by the shell as to fall towards the centre of the tube, 

 B, quite clear of the sides, thus producing the maximum effect in displacing 

 the air. The action of the siphon soon commences, and continues till the 

 water in the tank is lowered to the level of the lower mouth of A, after 

 which air is admitted by that mouth to the siphon, and the action ceases. 



In some cases, the quantity of air admitted at the end of the discharge, 

 though sufficient to stop the siphon, is not sufficient to fully charge it with 

 air, so that the next discharge will commence before the water in the 

 vessel has risen to its full height. To obviate this, the best expedient is 

 a secondary siphon, f, fixed in the trough, d, and put into action by the 

 discharge from the larger siphon, A B. "When this discharge has stopped, 

 the siphon f continues in operation, so that the water in the trough, D, is 

 drawn off, the lower mouth of the pipe, B, unsealed, and the larger siphon 

 fully charged with air. Presently, also, the action of the secondary siphon, 

 f, is also stopped by the admission of air. When the vessel is filled, and 

 water trickles over the shell, c, the trough d is again filled up to the level 

 of the weir, and the siphon A B becomes sealed. 



There are other minor conditions which affect the commencement of 

 the automatic action of the siphon, such as the roughness of the top of the 

 conical shell c, the ratio of the area of the tank to the area of the siphon, 

 the length of the siphon, &c, but these I will not go into. 



In conclusion, it is evident that the above form of self-acting siphon 

 will be of great practical use for a number of purposes. I will merely 

 mention one, namely, that of flushing sewers, by means of small quantities 

 of water which ordinarily run to waste. Take, for instance, a drinking 

 fountain, the water which escapes from it is, under ordinary circumstances, 

 absolutely useless for flushing purposes. Collect this water, however, in 

 a tank with a large self-acting siphon, and as soon as the tank is full, be 

 it in one day or in several days, the siphon will be brought into action, and 

 the contents of the tank discharged with great rapidity. The trickle from 

 a drinking fountain would start a siphon of as much as 10 or 12 inches' 

 diameter of the improved form, and would, therefore, flush a sewer of 

 considerable size, say nearly 3 feet in diameter. 



