In the 9th to 17th editions of Trautwine (1885-1900), these early accounts were superseded by numerous later instances, including some of those quoted by the author.
In the 18th and 19th editions (1902-1909) are given data respecting performances on the Catawissa Branch of the Reading (Shamokin Division) in 1898-1901. These give the maximum and minimum loads hauled up a nearly continuous grade of 31.47 ft. per mile (0.59%) from Catawissa to Lofty (34.03 miles) by engines of different classes, with different helpers and without helpers.
[Table 2] (in which the writer follows the author in assuming frictional resistance at 4.7 lb. per 2,000 lb.) shows the cases giving the maximum and minimum values of the quantity represented by the ordinates in the author's diagram, namely, "Traction, in percentage of weight on drivers."
It will be seen that the maximum percentage (16.1) is practically identical with that found by the author (16) for grade lengths exceeding 17 miles.
Near the middle of the 34-mile distance there is a stretch of 1.51 miles, on which the average grade is only 5.93 ft. per mile (0.112%), and this stretch divides the remaining distance into two practically continuous grades, 19.39 and 13.13 miles long, respectively; but, as the same loads are hauled over these two portions by the same engines, the results are virtually identical, the maxima furnishing two more points closely coinciding with the author's diagram.
TABLE 2.—Tractive Force, Catawissa to Lofty.
| 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 | |||||||||||||
| |||||||||||||||
| C | 1,631 | ||||||||||||||
| C | 1,126 | ||||||||||||||
| Traction (= B C ÷ 2,000) | Maximum[E] | D | 13.60 | ||||||||||||
| Minimum[F] | D | 9.38 | |||||||||||||
| |||||||||||||||
| E | 84.60 | ||||||||||||||
| E | 119.00 | ||||||||||||||
| Percentage ( = D ÷ E ). | |||||||||||||||
| Maximum | F | 16.1 | |||||||||||||
| Minimum | F | 7.9 | |||||||||||||
[ [E] Giving maximum values of percentage, F.
[ [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.