MEASUREMENT AND DIVISION OF WATER. 25 
As a general thing, the coefficients increase slightly 
as the depth decreases, so that for small depths, less than 
three inches, the discharge will generally exceed the 
computed amount by one or two per cent. 
A table giving the discharge for different depths over 
weirs of various lengths is given in the appendix, winch 
will be useful to those already using this system. 
THE CIPPOLETTI OR CANALE VILLORESI MODULE. 
A module based on the same principles and experi¬ 
ments, but differing in shape, is the module of the Canale- 
Villoresi. The Canale Villoresi—so named from the 
engineer who projected it—is the latest great Italian 
canal. Constructed in 1881-4, it waters some 65,000 
ettare, or 160,000 acres, between the Ticino and Adda, 
rivers. So important a public benefit did the project 
seem to be, that the. Provincial Council of Milan voted 
the money to construct it. Its cost was fully one fourth 
as much as all the canals in Colorado to-day. The- 
various modules in use had long been, unsatisfactory,, 
principally, according to Herrisson, for the reason that 
they favored the large users. 
In the act of concession, the government imposed the- 
condition of proposing a module for the measurement, 
and sale of water. The government required that it, 
should be founded on the theory of the weir with free fall,, 
and that it should give ample guarantees of security and 
accuracy. The problem was put in the able hands of 
Cesare Cippoletti, the director of the works. Much of the- 
following is condensed from his work : “Canale Villoresi ,- 
Modulo per la Dispensa delle Acqua, etc., Milan, 188C, 
published by the direction of the Societa Italiana per 
Condotte d’ Acqua. The problem Cippoletti proposed to 
himself was, while preserving the simple and convenient 
form of the formula of Francis, and a constant coefficient,. 
