222 SEWER DESIGN 



which allows of the instantaneous escape or falling away of the 

 heayed-up water. Thus if the discharge mouth were formed 

 as an ordinary bend, the siphon would not act (although the 

 confined air rushes around the lower bend), for the simple 

 reason that the heaved-up water has no means of instantaneous 

 escape, and therefore the equilibrium is not sufficiently dis- 

 turbed. It will thus be seen that the action of this siphon 

 depends, not on the escape of air, but on the sudden reduction 

 of a counterbalancing column of water. 



" Repeated trials with a 6-inch (Miller) siphon have shown 

 that it will discharge full bore a 5oo-gallon tank, fed so slowly 

 as only to be filled in fourteen days. 



" There being no internal obstruction, the discharge is 

 extremely rapid. 



" We have had the opportunity of seeing one of these siphons 

 at work in the excellent Sanitary Museum at Hackney, and, 

 though severely tried, the siphon worked perfectly." 



A special form of the " Miller Tank," designed by Andrew 

 Rosewater for use in the city of Omaha, Neb. (see Fig. 65), is 

 now manufactured. It is claimed that it discharges 40 per cent 

 faster than any other siphon of the same size. It does not 

 take the place of the inspection manhole, but affords easy access 

 for inspection during the working of the siphon. 



Fig. 66 * shows an automatic discharging siphon made by 

 the Merritt Company, of Camden, N. J., and embodying a 

 different principle. The main discharge pipe is built in the 

 form of a " U " tube, the longer leg containing an auxiliary 

 small air pipe, with a return bend at its lower end. When the 

 chamber starts to fill, this small pipe bend or seal is filled with 

 water, so that the rising water confines and compresses air in 

 both the large and small " U " pipes. In time, and at any 

 desired height, determined by changing the relative lengths of 

 the parts of the small -pipe siphon, the seal is broken and the 

 air escaping draws air enough from the large pipe to start it 



* From Ogden and Cleveland's "Practical Method of Sewage Disposal." 



