To the charge required.
Table for the Charges of Mines,
according to Valiere.
| Line of Least Resistance. | Charge for the Mine. | Line of Least Resistance. | Charge for the Mine. | ||
|---|---|---|---|---|---|
| Feet. | lbs. | oz. | Feet. | lbs. | oz. |
| 1 | 0 | 2 | 21 | 868 | 3 |
| 2 | 0 | 12 | 22 | 998 | 4 |
| 3 | 2 | 8 | 23 | 1140 | 10 |
| 4 | 6 | — | 24 | 1296 | — |
| 5 | 11 | 11 | 25 | 1558 | 9 |
| 6 | 20 | 4 | 26 | 1647 | 12 |
| 7 | 32 | 2 | 27 | 1815 | 4 |
| 8 | 48 | — | 28 | 2058 | — |
| 9 | 68 | 5 | 29 | 2286 | 7 |
| 10 | 93 | 12 | 30 | 2530 | 4 |
| 11 | 124 | 12 | 31 | 2792 | 4 |
| 12 | 162 | — | 32 | 3072 | — |
| 13 | 205 | 15 | 33 | 3369 | 1 |
| 14 | 257 | 4 | 34 | 3680 | 22 |
| 15 | 316 | 4 | 25 | 4019 | 8 |
| 16 | 384 | — | 36 | 4374 | — |
| 17 | 460 | 9 | 37 | 4748 | 11 |
| 18 | 546 | 12 | 38 | 5144 | 4 |
| 19 | 643 | — | 39 | 5561 | 2 |
| 20 | 750 | — | 40 | 6000 | — |
This table is calculated upon a supposition that the excavation of the mine is a paraboloid, having a base double the line of least resistance; and that 10 lbs. 10 oz of powder is sufficient for raising one cubic fathom of earth, by making the line of least resistance of the required globe only equal to the radius of the globe of compression.
The charges thus found by means of this table, being only for one nature of soil; viz. light earth and sand, (that for which the table is calculated) must be augmented according to the following table of Vauban’s, by one, four, five, seven, or nine elevenths of the charge found.
Table of the Quantity of Powder
required to raise a Cubic Fathom,
according to the Soil.
| 1 Light earth, mixed with sand | 11 pounds. |
| 2 Common earth | 12 |
| 3 Strong sand | 15 |
| 4 Clay, or fat earth | 16 |
| 5 Old and good Masonry | 18 |
| 6 Rock | 20 |
The following rule is however laid down by Belidor, and generally adopted, if it be intended that the mine shall produce its maximum or greatest effect: Multiply the line of least resistance, expressed in feet, by 300, the product will be the charge in pounds.
In making mines of any kind, the following remarks may be of service.