de, 2.44 miles, makes the tractive
power on it 92% of that on shorter grades.

On Hill _B_, the rating, adding 180 tons as above, is 1,160 and 1,230
tons, respectively, giving 94% for 3.57 miles.

On Hill _C_, the rating, with 180 tons added, is 1,130 and 1,230 tons,
making 92% for 4.41 miles.

Taking the same basis as the author, namely, 4.7 lb. per ton, rate of
grade x 20, and weight on drivers, gives:

Hill _A_, 18.078%, remainder of division, 19.462%
Hill _B_, 20.068%, " " " 21.279%
Hill _C_, 19.549%, " " " 21.279%

It will be noted that the author uses the weight on the drivers as the
criterion, but the tractive power is not directly as the weight on the
drivers, some engines being over-cylindered, or under-cylindered; in the
class of engines above mentioned the tractive power is 23.35% of the
weight on the drivers.

The writer made a study of several dynamometer tests on Hill _C_. There
is a grade of the same rate, about 1 mile long, near this hill, and a
station near its foot, but there is sufficient level grade between this
station and the foot of the hill to get a good start.

All the engines of the above class, loaded for Hill _C_, gained speed on
the 1-mile grade, but began to fall below the theoretical speed at a
point about 2-1/4 miles from the foot of the hill. This condition
occurred when the trains stopped at the station and also when they
passed it at a rate of some 16 or 18 miles per hour, the speed becoming
less and less as the top of the hill was approached.

The writer concludes that the author might stretch his opinion as to
using heavier rates of grade on shorter hills than 10 miles, and indeed
his diagram seems to intimate as much, and that, for economical
operation, the maximum rate of grade should be reduced after a length of
about 2 miles has been reached, and more and more in proportion to the
length of the hill, in order that the same rating could be applied all
over a division.

This conclusion might be modified by local conditions, such as an
important town where cars might be added to or taken from the train.

While it does not seem practicable to the writer to calculate what the
reduction of rate of grade should be, a consensus of results of
operation on different lengths of grade might give sufficient data to
reach some conclusion on the matter.

The American Railway Engineering and Maintenance of Way Association has
a Committee on "Rai