Transactions of the Institution of Engineers and Shipbuilders in Scotland Volume 28 (Paperback)

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1885 Excerpt: ...explicit value of f, which mechanicians distin guish as Morin's constant, as, 21,010 E 1 t0) t_ das N Log-i (a--n) V The perfect agreement of these formulae with the facts of experience has been illustrated so often that it is almost a waste of time to adduce further examples. I will note, for a few vesssels, the values of a and b which enter equation (4), which is the approximate true form of the " Admiralty " equation, the ordinary well known forms being founded on a false law of the resistance, are entirely misleading and erroneous. According to this, the relation between the power and speed, say, for example, in the small vessel "Warsaw," is, E= 2 97 VLog-i 111 V; hence, for the following speeds, Trial Speeds Product by-111 Log V Log 2-97 Log E.'. E By Trial, = 1-6727 2-1871 2-5097 2-7201 = 47-1 1540 323-4 525 47 153 324 525 The agreement of these figures is closer than we have any right to expect, considering the many sources of uncertainty which affect the data by which the relation of power and speed is determined in progressive speed trials. I shall now illustrate the calculation of the va'ue of "Morin's" constant by formula (5), taking, for example, H.M.S. "Heroine," which has been referred to by Mr Denny, I presume, as an example of the absurdity of my method of treating the question. The data for this is given iii the last issue, "Results of trials made in Her Majesty's screw ships and vessels," as follows: --The remaining necessary data are, d = 36; s = 2-5; whence, In the foregoing each trial gives its own value and testimony to the truth of the mechanical principles involved in the equation, and the very exception shown by the slight excess of value in' (2) is only an indication that the reporte...