of the tank; a glass with scale is used outside in summer time. Each inch
in height on the scale is converted into cubic feet, and then by means of
a table is converted into Russian poods, according to the specific gravity
at various temperatures. As it would be superfluous to graduate the table
for each separate degree of temperature, the columns in the table show the
weights for every 8 degrees Reaumur, which is quite sufficient: namely,
from 24 deg. to 17 deg., from 16 deg. to 9 deg., and so on, down to -24
deg.; the equivalent Fahrenheit range being from 86 deg. down to -22 deg.
Suppose the filling of a tender tank draws off a height of 27 in. from the
distributing tank, at a temperature of say -20 deg. R., these figures are
shown by the table to correspond with 200.61 poods = 7,245 lb., or 3.23
tons, of petroleum. This arrangement does very well in practice; both the
quantity and the temperature are entered on the driver's fuel bill at the
time of his taking in his supply.

_Engines._--The engines used in the trials were built by Borsig, of
Berlin, Schneider, of Creusot, and the Russian Mechanical and Mining
Company, of St. Petersburg. Their main dimensions and weights were about
the same, as follows, all of them having six wheels coupled, and 36 tons
adhesive weight; as originally constructed they had ordinary fire boxes
for burning anthracite or wood; cylinders 18-1/8 in. diameter and 24 in.
stroke; slide valves, outside lap 1-1/16 in., inside lap 3/32 in., maximum
travel, 4-9/16 in.; Stephenson link motion; boiler pressure, 120 lb. per
square inch; six wheels, all coupled, 4 ft. 3 in. in diameter; distance
between centers of leading and middle wheels, 6 ft. 2-3/4 in.; between
middle and trailing, 4 ft. 9-1/4 in.; total length of wheel base, 11 ft.;
weight empty, on leading wheels, 12.041 tons; middle, 10.782 tons;
trailing, 10.685 tons; total weight, 33.508 tons empty; weight in running
order, on leading wheels, 12.563 tons; middle, 11.885 tons; trailing
12.790 tons; total weight, 37.238 tons in running order. Tubes number 151;