SPILLWAYS FOE RESERVOIRS AND CANALS. 



21 



1, Plate XII, and the arrangement of piezometer tubes and gage 

 board in figure 2, Plate XII. A diagram of the testing laboratory 

 and the setting of the siphons on the crest is shown in figure 1. 

 Plate XIII. 



The Fort Collins models were larger than those at Throop College 

 and were designed as a miniature of the Phoenix siphon shown in 

 figure 8 and hinged to permit of changing the shape of the outlet leg. 



The tests were conducted to ascertain : 



Fig. 7. — Outline section of type of siphon spillway built by Gregotti in Italy. Note 

 submerged intake lip and surface air control intended for use where floating trash or 

 ice interferes with operation. 



(a) The theoretical and actual loss of head in the various parts. 



(b) The effects of various shapes of parts upon head loss in that 

 part and upon the general efficiency. 



(c) The total efficiency of the structure and to determine a value 

 for k in the formula Q = kAy2gH for different shapes. 



(d) The relation between the depth of submergence of the dis- 

 charge lip and the depth of water over the throat to bring the siphons 

 into action under different conditions of air inlet. 



