The character of theoretical information imparted by some Chicago Journal of Commerce, dated 20th February, 1884.  There we are informed that “the height of the fall is one of the most important considerations, as the same stream of water will furnish five times the horse power at ten ft. that it will at five ft. fall.”  By general consent twice two are four, but it has been reserved for this imaginative writer to make the useful discovery that sometimes twice two are ten.  Not until after the translation of Captain Morris’ work on turbines by Mr. E. Morris in 1844, was attention in America directed to the advantages which these motors possessed over the gravity wheels then in use.  A duty of 75 per cent. was then obtained, and a further study of the subject by a most acute and practical engineer, Mr. Boyden, led to various improvements upon Mr. Fauneyron’s model, by which his experiments indicated the high duty of 88 per cent.  The most conspicuous addition made by Mr. Boyden was the diffuser.  The ingenious contrivance had the effect of transforming part of whatever velocity remained in the stream after passing out of a turbine into an atmospheric pressure, by which the corresponding lost head became effective, and added about 3 per cent. to the duty obtained.  It may be worth noticing that, by an accidental application of these principles to some inward flow turbines, there is obtained most, if not all, of whatever advantage they are supposed to possess, but oddly enough this genuine advantage is never mentioned by any of the writers who are interested in their introduction or sale.  The well-known experiments of Mr. James B. Francis in 1857, and his elaborate report, gave to hydraulic engineers a vast store of useful data, and since that period much progress has been made in the construction of turbines, and literature on the subject has become very complete.

In the limits of a short paper it is impossible to do justice to more than one aspect of the considerations relating to turbines, and it is now proposed to bring before the Mechanical Section of the British Association some conclusions drawn from the behavior of jets of water discharged under pressure, more particularly in the hope that, as water power is extremely abundant in Canada, any remarks relating to the subject may not fail to prove interesting.

Between the action of turbines and that of screw propellers exists an exact parallelism, although in one case water imparts motion to the buckets of a turbine, while in the other case blades of a screw give spiral movement to a column of water driven aft from the vessel it propels forward.  Turbines have been driven sometimes by impact alone, sometimes by reaction above, though generally by a combination of impact and reaction, and it is by the last named system that the best results are now known to be obtained.