======
Length of grade, in miles | | 34.03
| |
Grade {in feet per mile | | 31.47
{percentage |_A_ | 0.597
| |
Resistances, in pounds per 2,000 lb., | |
Gravity (=20 _A_) = 11.94. Friction = 4.70 |_B_ | 16.64
| |
Load: | Cars. | Locomotive.| Tender. | |
Maximum[E] | 1,561 | 44.60 | 25.25 |_C_ | 1,631
Minimum[F] | 1,031 | 60.50 | 34.50 |_C_ | 1,126
| |
Traction (= _B_ _C_ / 2,000 ) Maximum[E] |_D_ | 13.60
Minimum[F] |_D_ | 9.38
Weight on Drivers: | Locomotive.| Helper. | |
Maximum[E] | 21.60 | 63.00 |_E_ | 84.60
Minimum[F] | 47.00 | 72.00 |_E_ | 119.00
| |
Percentage ( = _D_ / _E_ ). | |
Maximum |_F_ | 16.1
Minimum |_F_ | 7.9
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FOOTNOTES:

[Footnote E: Giving maximum values of percentage, _F_.]

[Footnote F: Giving minimum values of percentage, _F_.]

BEVERLY S. RANDOLPH, M. AM. SOC. C. E. (by letter).--The percentages
given by Mr. Purdon would seem to indicate that the length of the grades
did not affect the loads in the cases cited, but these percentages are
so much below those shown in the table, for similar distances, as to
indicate some special conditions which the writer has been unable to
find in the text.

The use of the percentage of weight on drivers which is utilized in
traction as a measure of the efficiency of the locomotive, while,
probably, not applicable to individual machines, is sound for the
purposes of comparison of results to be obtained on various portions of
a line as far as affected by conditions of grade and alignment. It has
the advantage of disregarding questions of temperature, condition of
track, character of fuel, etc., which, being the same on all portions of
the line, naturally balance and do not