20 
MEASUREMENT AND DIVISION OF WATER. 
one ordinarily meant when weir is spoken of, and the one 
which has been the subject of experiment; and the trape¬ 
zoidal weir proposed by Cippoletti, after a thorough in¬ 
vestigation. Its sides are inclined at a slope of one-fourth 
horizontal to one vertical. 
WEIRS. 
The most complete experimental investigation of the 
flow of water over weirs was made bv an American, 
J. B. Francis, of Lowell, Mass. At that point were lo¬ 
cated a number of manufacturing enterprises drawing 
their water from the Merrimac River, with a combined 
capital of over thirteen millions qf dollars. It became 
necessary to determine more definite measurement of the 
« 
water, and Francis’ experiments were instituted for this 
purpose. Carried on with all the appliances and conven¬ 
iences which the capital interested would warrant, the ex¬ 
periments were performed with such care and such atten¬ 
tion to minute sources of error that they are above 
criticism. 
9 ' 
One difficulty in such experiments is to obtain a suit¬ 
able basin in which to measure the water. In this case 
Francis was fortunate in having one suitable in the Lower 
Locks, into which the water could be deflected at will 
after passing the weir. The lock w T as carefully prepared. 
Cracks were filled, leaks stopped, even the depressions 
about nail heads cemented up. The remaining leakage 
was ascertained by experiment. The slight increase in 
capacity due to bulging when full was ascertained. The 
total capacity of the basin when 9J feet deep was over 
12,000 cubic feet. 
A. preliminary set of experiments was made for deter¬ 
mining the proper form of the equation, and after this 
was determined the main experiments were devoted to 
finding the value of the coefficient of the formula. The 
