SPILLWAYS FOR RESERVOIRS AND CANALS. 
31 
the effects of this departure and verify or correct the theory of the 
parting water column in siphons under relatively high heads would 
be of benefit, and the tests taken on the Yuma installation, where 
the design is identical 
except for the converg- 
ing outlet, could be con- 
trasted. 
As a method of auto- 
matically safeguarding 
the freeboard of a canal 
at isolated points, the 
small siphon shown in 
figure 2, Plate XI, and 
in text-figure 11 is a 
good example. These 
figures illustrate the 
siphon at the head of the 
East Park Feed Canal of 
the Orland project. It is 
designed to operate when the water stands 
0.2 foot above the top of the waste weir 
at the place of diversion, and thus fur- 
nish a close regulation of the water sur- 
face. The estimated capacity is 99 sec- 
ond-feet, with 0.50 taken as the discharge 
coefficient. This was one 
stallations in the United States and followed the 
European custom of inclined draft tube, the slope 
of the ground at the site being particularly 
adapted to the design. 
EUROPEAN PRACTICE. 
The Italian engineer Luigi Luiggi describes 
numerous siphon spillways which have applied to 
dams and to many power and irrigation canals. 1 
prevailing type is a square tube built of reinforced con- 
crete and capable of discharging from 1 to 525 second- 
feet, varying, of course, according to section and the head 
under which they operate, which ranges up to 34 feet. 
To produce larger discharges where head was limited, siphons are 
placed in batteries. A typical example of clever control by the siphon 
spillway is shown in the case of the Logalunga Reservoir, near Genoa, 
1 Transactions of the International Engineering Congress, 1915, Waterways and Irriga- 
tion Section. 
