— 6 — 
uring box which has in general for an object to give the con¬ 
sumer a certain definite quantity of water, as one cubic foot 
per second, d'hese need to be adjustable, so that in times of 
scarcity the amount may be reduced proportionately as the 
quantity in the canal decreases. To this last class the Italians 
give the name of modulo. The French writers on irrigation, 
and to a limited extent the English, have adopted the word 
in the form of module, and, as such a word is needed in our 
irrigation vocabulary, the term is here used. Module will 
therefore be used to designate those boxes or devices, what¬ 
ever their form, whose object it is to measure the quantity of 
water delivered, or to give a constant flow. The word divisor 
will be restricted to the first class, whose only object is to di¬ 
vide the water. A module may evidently serve as a divisor, 
for if the amount to be divided is known it is a simple matter 
to determine the quantity to which each is entitled and to 
regulate the module accordingly. There will always be cases 
where divisors will be by all means the most convenient, but 
these cases will be mostly in the small ditches from which 
few take water. In all other cases modules of one kind or 
another will be found the better. 
In the case of divisors it is evident that there is no unit of 
measure, and that none is needed, as the object is to give the 
consumer some definite portion of the water flowing in the 
ditch whether there be much or little. 
In the module, on the contrary, some unit is needed. j 
It is unfortunate that a system has grown up in which the 
professed unit is the “inch.” The word is used in such a mul¬ 
titude of meanings that it is an almost hopeless task to con- i 
vey an exact idea of quantity by the word. It in effect takes j 
into account only the cross-section of the channel or opening, j 
without regard to the velocity of the water. In the same \ 
ditch it is attempted to have the velocity the same or nearly 3 
the same through the different openings, by keeping the head i 
the same, but in different ditches the heads vary according to ; 
convenience or the notions of the original users. In some ji 
ditches the head is four inches, in others six, in some eight, ; 
and there are others which allow the opening to extend to • 
the surface of the water and no pressure is used. The whole I 
area of the opening in square inches is then counted as inches ; 
of water. Also, in common use, a practice has grown up to i 
call the cross-section of the stream in square inches, without ; 
regard to the velocity of the water, as so many “ inches.” i 
Manifestly there is nothing in common in these different i 
inches, so that the term has no definite meaning. The legal i 
