The chart illustrated in Fig. 8 is that for steam-shovel work on the same contract of the Construction Service Company. Line A indicates the approximate number of yards moved per day. Line B shows the pay-roll, ranging from $165 to $310 per day, and including a percentage for incidentals; while line C represents the values of the B quantity divided by the A quantity, and gives the unit-cost in labor per yard for excavating and moving rock. It will be noted that the Sundays are skipped. These came on the 5th, 12th, 19th, and 26th of the month. There were some men employed on each of these Sundays; but their time was so distributed over the rest of the month as not to show for the Sundays, as the steam shovels did not work on that day.
Fig. 7. Efficiency Chart Indicating Cost of Channeling Rock.
Fig. 8. Efficiency Chart Showing Costs in Connection with Steam-Shovel Work in Rock Excavation and Removal.
These charts are of a size to be filed in one of the standard loose-leaf books, and their range is from zero to about 12; thus it is possible to show any quantity to scale for any day in the month. This company has not found it of advantage to plot more than 4 lines on any one chart.
Charts such as these may be marked each morning by the time-keeper upon a tracing prepared for this purpose; and at the end of the month the lines connecting the points may be inked in, and the chart blue-printed and the blue-print filed in a convenient place for immediate reference.