MEASURE OF MOVING FORCE. 141 
various problems according to the principles he 
had assumed. He compared the conclusions 
from the common theory of fluids with the results 
of Smeaton’s experiments on water wheels, (Phil. 
Trans. 1759,) arriving at interesting conclusions; 
but the more recent investigations on this subject 
by Poncelet and others; with the very important 
experiments of the committee of the Franklin 
Institute, upon wheels of 20, 15, 10, and 6 feet 
diameter,—together with those of M. Morin, on 
the Turbine of M. Fourneyron,—have placed 
all others in the shade. Mr. Ewart made many 
experiments on the reaction of effluent water, 
and applied the results of his researches on 
this subject to the solution of the problem of the 
recoil engine, known by the name of Barker’s 
Mill. This part of the paper was reprinted in 
1828, in the Philosophical Magazine, with notes 
relating to the theory of Barker’s mill by the late 
Mr. Ivory. This great mathematician, in solving 
the problem, compared the results of Euler’s, 
Bossut’s, and Mr. Ewart’s solutions, and added 
other enquiries of his own. 
In following the reasonings in Mr. Ewart’s 
paper, though generally sound, the reader has to 
encounter difficulties from a change of names, and 
