—_ Messrs. peaisecagy Abbot. 17 
state of the case: each engineer is obliged to collect the wpa 4 part of 
his knowledge from his own experience, ane by many dear bought lessons 
to direct his future operations, in hig e still proceeds with anxiety 
and hesitation: for we have not yet acquir red principles of theory, and 
experiments have not yet nae aR Peet and pone by which an em- 
_ pirical practice might be safely formed. * The motion of waters has 
be n-really so little investigated, that hydra may still be called a new 
study.” And again 
“As to the uniform course of the streams which water the face of the 
wishes, w e in a manner totally. ignorant. Who n pretend to say 
ees is ti veloc 0 of hy river, of which you tell hi: the broadiie the 
ions. 
are the want or uncertainty of our principles; the falsity of our theory, 
which is belied by experience; and the small number of proper observa- 
tions or experiments, and difficulty of abbey such as shall 
viceable.” 
Tn asserting that this extract continues to represent the state 
of the science of river hydraulics at the present day, as com- 
_ pletely as it did at the close of the last en at when it was 
4 solutions in the works of the highest authorities on the subject, 
at the on ce, time, as they were then. And thx . Ro! 
himself proceeds to set “Porth a system—theoretie aise ractical 
—mainly adopted. from Dubuat, Thich an concludes with affirm- 
ing that he has “ established,” ‘and w hich he assures us “may 
+f : 
_ opinions and practice of our ablest engineers have been, and are 
_ yet, most widely at variance in regard to the airceilost problems 
_ which present themselves relating to the control and manage- 
_ ment of our natural streams; or that, just in proportion as —_ 
_ Streams are large, or are fed by numerous tributaries, dra 
_ their waters from regions tS to diversified climatic viciaat 
Am. Jour. — Senies, VoL. XXXVI, No. 106.—Juxy, 1863. 
