In such a case, the letters
designating each elementary unit are entered under the columns "Op.,"
the stop watch is thrown to zero, and started as the man commences to
work. As each new division of the operation (that is, as each
elementary unit or unit time) is begun, the time is recorded. During
any special delay the watch may be stopped, and started again from the
same point, although, as a rule, Mr. Thompson advocates allowing the
watch to run continuously, and enters the time of such a stop,
designating it for convenience by the letter "Y."
In the case we are considering, two kinds of materials were handled sand
and clay. The time of each of the unit times, except the "filling," is
the same for both sand and clay; hence, if we have sufficient
observations on either one of the materials, the only element of the
other which requires to be timed is the loading. This illustrates one of
the merits of the elementary system.
The column "Av." is filled from the preceding column. The figures thus
found are the actual net times of the different unit times. These unit
times are averaged and entered in the "Time" column, on the lower half
of the right-hand page, preceded, in the "No." column, by the number of
observations which have been taken of each unit. These times, combined
and compared with the gross times on the left-hand page, will determine
the percentage lost in resting and other necessary delays.
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