Let
a = time filling a barrow with any material.
b = time preparing to wheel.
c = time wheeling full barrow 100 feet.
d = time dumping and turning.
e = time returning 100 feet with empty barrow.
f = time dropping barrow and starting to shovel.
p = time loosening one cubic yard with the pick.
P = percentage of a day required to rest and necessary delays.
L = load of a barrow in cubic feet.
B = time per cubic yard picking, loading, and wheeling any given kind of
earth to any given distance when the wheeler loads his own barrow.
[Transcriber's note -- formula and Tables omitted]
This general formula for barrow work can be simplified by choosing
average values for the constants, and substituting numerals for the
letters now representing them. Substituting the average values from the
note sheet on Fig. 2 (page 151), our formula becomes:
[Transcriber's note -- formula omitted]
In classes of work where the percentage of rest varies with the
different elements of an operation it is most convenient to correct all
of the elementary times by the proper percentages before combining them.
Sometimes after having constructed a general formula, it may be solved
by setting down the substitute numerical values in a vertical column for
direct addition.
Table 3 (page 164) gives the times for throwing earth to different
distances and different heights.
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