THE DETHRIDGE METER 
By V. M. Cone, Irrigation Engineer, U. S Office of Public Roads 
and Rural Engineering. 
The Dethridge meter is a device for measuring water flowing 
in open channels. It is the invention of Mr. J. S. Dethridge, mem¬ 
ber of the State Rivers and Water Supply Commission of Victoria, 
Australia, and several thousands of them are in use in different parts 
of Australia for measuring irrigation water. At the present time 
few are in use in the United vStates, except for experimental pur¬ 
poses. In Australia, but one size of meter, the 5-foot wheel, is used, 
and where it is necessary to measure the flow in a ditch in excess 
of the capacity of a single meter, two or more wheels are placed 
side by side with walls between them to divide the flow. 
For the purpose of better adapting the Dethridge meter to irri¬ 
gation conditions in the United States, three sizes of wheels, with 
no essential changes in Mr. Dethridge’s design, were experimented 
with at the hydraulic laboratory at Fort Collins, Colo., during the 
summer of 1915. The statements in this bulletin are based on these 
experiments.* 
The meter consists of a drum with projecting vanes sO' placed 
in the box or structure in the ditch that there is a uniform clear¬ 
ance of from one-fourth to three-eights inch between the walls of 
the box and sides of the wheel, and also' between the vanes and the 
curved floor of the box. Spokes made o^f 2x4 lumber are placed 
inside the drum; one set of spokes in each end of the drum for the 
smaller sizes, and a third set in the middle for the largest sized 
drum. 
A horizontal shaft made of one-inch pipe is placed through 
the spokes at the center of the drum and this shaft is supported in 
a horizontal position by 4x4 wood block bearings. A bearing made 
by boring a hole in a 4x4 block of wood is durable and entirely 
satisfactory if oiled occasionally. A large nail placed through a 
hole bored in the pipe shaft and stapled to one of the spokes will 
prevent the wheel from turning on the shaft. It may be necessary 
*Other experiments with this meter have been made by the Office of Ex¬ 
periment Stations in co-operation with the University of California at Davis, 
Cal., the results being published in California University Agricultural Experi¬ 
ment Station bulletin 247. 
