10 
MEASUREMENT AND DIVISION OF WATER. 
9. It should occupy but small space. 
*10. It should require but little fall or expense. 
These conditions are evidently not of equal impor¬ 
tance, and under different circumstances the weight given 
to each condition may vary. As water becomes more 
scarce those relating to accuracy become relatively more 
important. A module which has been satisfactory may 
become unsuited when these conditions become more im¬ 
portant. 
The old Italian modules are mostly based on an 
orifice of determinate size, with a constant pressure. Our 
statute inch is such a module. Some are circular, as the 
acqua Paola, but most are rectangular, of various dimen¬ 
sions. Those of the same kind had the same height of 
orifice and the same pressure. Different amounts were 
given by giving greater horizontal lenght to the orifice. 
The Milanese module, due to the engineer Soldati, is the 
most celebrated. The canals of that province having fal¬ 
len into great disorder, the magistracy of Milan attempted 
to regulate them, and gave twelve conditions which a 
module should satisfy.f In response to these, Soldati 
proposed the module which has ever since been known as 
—-=_ =s==i 
N 
- -=3F-—— 
Canal ^ 
-— 
i 
Fig. 2. 
the Milanese module. The first thing he considered im¬ 
portant was to insure that the water should flow with uni¬ 
form pressure. This he attempted to do by the following 
principle: 
f Note— The history of this event and the trouble is given in Brnschelti’s 
■“Storm del lrrigazioni del Milanese,” in his collected works, Vol. II., pp. 118-13T:, 
condensed in liuffon. The conditions are all included in those given above. 
