corresponding maximum grades are as tabulated.

Length in miles. Steepest grade
Boston to Worcester, 44 30
Worcester to Springfield, 541/2 50
Springfield to Pittsfield, 52 83
Pittsfield to Albany, 431/2 45

A load of five hundred tons upon a grade of thirty feet per mile
requires of the locomotive a drawing-power of 11,500 lbs.

Upon a 50 feet grade 15,500 lbs.
Upon an 83 feet grade 22,500 lbs.
Upon a 45 feet grade 14,500 lbs.

Now, if the engines are all alike, (as they are very nearly,) and
each is able to exert a drawing-power of five thousand pounds to
move a load of five hundred tons from Boston to Albany, we need as
follows:

B. to W.--11500/5000 or 2 engines.
W. to S.--15500/5000 or 3 engines.
S. to P.--22500/5000 or 5 engines.
P. to A.--14500/5000 or 3 engines.

From which the whole number of miles run by engines for one whole
trip would be,--

B. to W. 44 miles by 2 engines, or 88
W. to S. 541/2 miles by 3 engines, or 1631/2