The actual working time of the drills in the 736 shifts (7,360 hours) covered by Table 1, was 3,826 hours, or 5.2 hours per shift. The average depth drilled per yard, as shown in the last column of Table 1, agrees fairly well with the figures on the diagrams, Figs. 1, 2, 3, and 4.
Table 2 has been compiled from detailed timed observations of individual drilling of down holes in the bench, for periods of 7 or 8 hours each, in January, 1907. The work at that time was in fairly normal condition at all points.
The figures in the third column of Table 2 include the time required for moving from one hole to another, when this occurred during the observation, the time required for changing bits, oiling drills, etc., and all delays of all kinds. A close record of the delays was
kept, and it was considered that, of the 93 hours, 48 min., in Table 2, the unnecessary delays amounted to 5 hours, 7 min., or about 5½ per cent.
[TABLE 1.]
| Shifts: Number of shifts covered by observations. Hours: Average number of hours worked per shift. D/Hr: Average depth drilled per hour per drill D/Yd: Average depth drilled per yard. | Hack.: Hackensack Whk.: Weehawken CS: Central Shaft |
| Method. | Date. | Shifts | Place. | Hours | D/Hr | D/Yd | |
No. 1— | Aug. ’06 | 44 | Hack., | N. | 5.69 | 2.78 | 10.1 |
| Sept. ’06 | 38 | ” | N. | 5.80 | 3.77 | 11.1 | |
| Aug. ’06 | 43 | ” | S. | 5.60 | 2.89 | 9.1 | |
| Sept. ’06 | 36 | ” | S. | 6.18 | 2.65 | 8.7 | |
| Jan. ’07 | 16 | CS E. | N. | 5.99 | 2.99 | 8.2 | |
| Jan. ’07 | 20 | ” | S. | 6.05 | 2.9 | 7.1 | |
| Apr. ’07 | 48 | CS W. | N. | 4.92 | 3.3 | 6.7 | |
| Apr. ’07 | 48 | ” | S. | 5.00 | 3.2 | 7.7 | |
Nos. 2 and 3— | Dec. ’06 | 54 | Whk., | N. | 4.95 | 2.16 | 4.52 |
| Dec. ’06 | 54 | ” | S. | 5.23 | 2.14 | 4.54 | |
| Dec. ’06 | 52 | Hack., | N. | 5.03 | 2.2 | 5.77 | |
| Dec. ’06 | 54 | ” | S. | 5.90 | 1.82 | 5.67 | |
No. 4— | June ’07 | 56 | Whk., | N. | 4.77 | 2.55 | 4.23 |
| June ’07 | 58 | ” | S. | 4.82 | 2.26 | 3.88 | |
| May ’07 | 60 | Hack., | N. | 4.67 | 2.44 | 5.00 |
| May ’07 | 60 | ” | S. | 4.54 | 2.57 | 4.80 | |
[TABLE 2.]
| Date. | Place. | Total working time. | Number of feet drilled. | ||
| Hours. | Minutes. | ||||
| Jan. 14th, 1907 | Weehawken | N. | 8 | 0 | 15 |
| ” 15th, 1907 | ” | N. | 7 | 32 | 12 |
| ” | N. | 7 | 22 | 14 | |
| ” 12th, 1907 | ” | S. | 8 | 0 | 20 |
| ” | S. | 8 | 0 | 11 | |
| ” | S. | 8 | 0 | 10 | |
| ” 11th, 1907 | Hackensack | N. | 8 | 0 | 13 |
| ” 17th, 1907 | ” | N. | 7 | 10 | 10 |
| ” | N. | 7 | 5 | 11 | |
| ” | N. | 7 | 10 | 10 | |
| ” 16th, 1907 | ” | S. | 4 | 20 | 10 |
| ” | S. | 6 | 9 | 10 | |
| ” | S. | 7 | ... | 8 | |
| Totals. | 93 | 48 | 154 | ||
Average: 36.6 min. per ft. drilled, or 1.64 ft. drilled per hour.