4 The Colorado Experiment Station. 
small or where the land to be supplied is nearly on the same level 
as the canal. Methods to be used where the water is clear may 
be impossible in streams carrying large quantities of silt. Likewise, 
the methods must often be adapted to satisfy conditions of local con¬ 
tracts or to accord with local customs. No system will work without 
intelligent supervision. A poor method may work out satisfac¬ 
torily, provided the man in charge has experience and good judg¬ 
ment. Sometimes even a good system will not be free from trouble 
unless administered by capable men. Hence one of the necessary 
requirements in canal management is to educate the superinten¬ 
dents and riders so that they have sufficient understanding of the 
principles of measurement to apply them to the exceptional cases. 
The men also need the confidence of the users. Users are sus¬ 
picious, and hence it is as important, perhaps more important, for 
the successful management of a canal, to have a system which 
appears to be fair as to have one which is fair, but is not appar¬ 
ent. Hence an important feature is a measurement which shall 
be simple and which may be understood by the user. It thus saves- 
unpleasant disputes and arguments, strengthens the faith in the 
ditch rider, and relieves him from clamor of those who think that 
the way to get their share is to claim more than they are 
entitled to. 
The bulletin will describe some methods of the division of water 
adapted to the use of small ditches and laterals, and also methods 
of measurement which may be used in large ditches. It especially 
explains the use of the weir, the conditions under which it should 
be placed and the extent to which it can be relied upon, and also- 
tables for its use. 
In the previous editions of this bulletin, descriptions were made 
of the rectangular and of the trapezoidal weir with sides inclined 
at one-fourth to one. The description of this weir in 1890 was the 
first description of this form of weir in English. Because it 
had been proposed by the engineer of an Italian canal, I called 
it after him, the Cippoletti weir. From the description and recom¬ 
mendation given in Bulletins 13 and 22, its use has widely 
spread over the irrigated sections. It has been adopted by 
various experiment stations, by the state engineers of all of 
the western states, and by the United States Department of 
Agriculture, but in most cases without credit to the author or 
to the station. The recommendation given in Bulletin 13, (1890),. 
and Bulletin 27, (1894) has sometimes been taken too broadly, but 
as a whole the endorsement there given has been justified. The 
statement there made that I considered it to be the most advan¬ 
tageous of any module for irrigation purposes, should not be taken 
to mean that it is the most accurate. The only advantage over the- 
