The introduction of the first machine into the tunnel, before its capacity, strength, and expense of working had been fully tested, was unfortunate, inasmuch as its use there delayed the progress of the work. The second machine gives such promise of success, that it will be continued in use in the tunnel until a fair test has been made. But should the Burleigh machine prove unsuccessful, and further attempts with machines be attempted, the Committee recommend that their usefulness be tested outside of the tunnel, and meanwhile the excavation with hand drills be resumed.
Experiments with Dr. Ehrhardt's Powder.
The first blast was fired in the tunnel at the East End on the 20th of November, but owing to the presence of charcoal or some other substance in the article, a poisonous gas was evolved which effected the miners disagreeably, and drove them from the work. The subsequent experiments at this point were not satisfactory, and were discontinued, and subsequently resumed at the Central Shaft, where it was used most of the time for a week, varying its composition from time to time. At the close of the week, while preparing for the last blast, a premature explosion took place, resulting in the death of one of the miners, and the injury of three or four others.
The material result of this experiment was as follows:—With 261 days' work and 1391/2 lbs. of powder, 202 buckets of stone were removed; while in the preceding week, using common powder (schaghticoke) with 2513/4 days' labor and 236 lbs. of powder, 168 buckets of stone were taken out. The cost of the experimental powder is about twice as expensive as the common powder, and its superior strength is apparent from the above result.
Experiments with Nitro-Glycerine.
During the summer, some experiments have been made with this explosive agent. A quantity, costing $934.29, was brought to the works by Colonel Schaffner, who exhibited the action of the material in various ways, with a view of testing its power, and the comparative safety of introducing it instead of powder. After repeated trials outside of the works, during which about three-fifths of the material was consumed, it was introduced into the tunnel at the West Shaft with the following result: It was used for three days at the East heading of the West Shaft; the advance made in the heading was for the time, 141/2 feet;—being an advance of 4.82 feet per day, and at the rate of 125.33 feet per month.
| In these three days there were taken out of the enlargement 151.76 yards of stone. To remove this quantity with powder would cost, on an average, per yard, | $9 84 | ||
| Actual cost with glycerine, | 6 20 | ||
| Difference, | $3 64 | ||
| Multiplied by 151.76, gives. | $552 40 | ||
| In the same time there was removed of heading 60.15 yards. | |||
| To remove an equal amount by powder costs, per yard, | $16 25 | ||
| Actual cost with glycerine, per yard, | 6 05 | ||
| Difference, | $10 20 | ||
| $10.20 multiplied by 60.15, gives | 613 53 | ||
| $1,165 93 | |||
| Cost of the glycerine used during the three days, being 2/5 of $934.29, | 350 36 | ||
| Saved, by using glycerine, in three days, | $815 57 | ||
| Which is a saving by the use of glycerine, per day, of | $276 85.4 | ||
| and allowing three hundred successful working days in the year, an annual saving of | $81,557 40 | ||
The progress made at the West Shaft on the East heading the present year, ending December 31, 1866, is 626 feet and 8 inches. This progress was somewhat lessened by the influx of water in December. The monthly advance has been 52 feet and 2 inches. The average of the eleven months ending with November is 53 feet and 6 inches. Assuming the progress made with glycerine during the three days of its use to be obtainable throughout the year, the monthly progress, using that material, would be 120 feet and 10 inches, on a calculation of twenty-five days to a month, which would give an annual advance of 1,450 feet.