MARINE ENGINES.
SIS
constant quantity in all the experiments, so long as the conditions ofthe trial are unchanged. We thus completely remove the objection-able variations of coefficient of the Admiralty formula, which, in thesame vessel and circumstances, usually gives a new value of C forevery value of V.
To illustrate the constancy of the derived coefficient, in passingfrom vessel to vessel, let us make use of experimental data which,treated by the Admiralty formula, offer great variations; for ex-ample, to a few cases of paddle vessels with feathering floats, ofwhich (except the Paris ), having only one experiment, and con-sequently being unable to determine a, it is assumed that thevalue of this is '0796. (Tabular results of experiments are given bythe author.) The problem therefore is, having given the length andarea, power and corresponding speed, of certain paddle vessels, tocalculate from the formula,
C ? = (L log- _1 '0796 v,
the value of C the efficiency coefficient, and to contrast the samewith the values yielded by the formula,
C ~ = M V 2 .
Resblts of Calculation of Efficiency of the following Paddle Vessels.
Name.
Length.
Mid. Area.
Log.(L-v/M )3
Trial
Power.
Correspond-ing Speed.
Efficiency
Co-efficient.
Admiralty
Co-efficient.
Shannon ,..
329
610
3-4212
2928
13-90
i6o-o
559-5
Paramatta ,
329
606
3'4199
2940
J 3 ' 9 S
160-9
56°-O
Admiral , ..
211
214
3'°557
744
11-87
159-8
485-7
219
177
3-0248
1030
i 3 ‘ 4 i
161 -o
400’4
Wolf .
239
220
3U059
1500
14-19
I 59'2
39 ! -i
It will be seen that the formula virtually embracing the whole is,
E = (L / M) ^ V log. - 1 -0796 V.
160'4
The efficiency coefficient 160-4 giving as close a result as would beobtained by the use of three values of the Admiralty formula coeffi-cient, say 560, 486, and 400. Having thus exhibited the ränge andaccuracy of the proposed System of comparison with the ordinaryrun of merchant vessels, let us now apply them to the valuable datafurnished by Mr. White, so as to compare results.”
The author then proceeds to a comparison of various experi-mental results, and finds that the efficiency coefficient for vessels ofH.M. navy and mercantile marine vary from about 80 to nearly600, and points out that the conflicting elements which enter into