MINE
, in Fortification &c, is a subterraneous canal or passage, dug under any place or work intended to be blown up by gunpowder. The passage of a mine leading to the powder is called the Gallery; and the extremity, or place where the powder is placed, is called the Chamber. The line drawn from the centre of the chamber perpendicular to the nearest surface, is called the Line of least Resistance; and the pit or hole, made by the mine when sprung, or blown up, is called the Excavation.
The Mines made by the besiegers in the attack of a place, are called simply Mines; and those made by the besieged, Counter-mines.
The fire is conveyed to the Mine by a pipe or hose, made of coarse cloth, of about an inch and half in diameter, called Saucisson, extending from the powder in the chamber to the beginning or entrance of the gallery, to the end of which is fixed a match, that the miner who sets fire to it may have time to retire before it reaches the chamber.
It is found by experiments, that the figure of the excavation made by the explosion of the powder, is nearly a paraboloid, having its focus in the centre of the powder, and its axis the line of least resistance; its diameter being more or less according to the quantity of the powder, to the same axis, or line of least resistance. Thus, M. Belidor lodged seven different quantities of powder in as many different mines, of the same depth, or line of least resistance 10 feet; the charges and greatest diameters of the excavation, meaured after the explosion, were as follow:
| Powder. | Diam. | |
| 1st | 120lb | 22 2/3 feet |
| 2d | 160 | 26 |
| 3d | 200 | 29 |
| 4th | 240 | 31 1/4 |
| 5th | 280 | 33 1/2 |
| 6th | 320 | 36 |
| 7th | 360 | 38 |
Mine-Dial, is a box and needle, with a brass ring divided into 360 degrees, with several dials graduated upon it, commonly made for the use of miners.
