15 ENCYCLOPÆDIA PERTHENSIS. MIN (I.) MINE. n. mine, French; mayn or maun, Welth, from maen lapis, in the plural meini.] 1. A place or cavern in the earth which contains metals or minerals.In your large heart was found a wealthy mine. Waller. -A workman, to avoid idleness, worked in a groove or mine-pit thereabouts, which was little efteemed. Boyle-A mine-digger may meet with a gem, which he knows not what to make of. Boyle. The heedless mine-man aims only at the obtaining a quantity of fuch a metal as may be vendible. Boyle. 2. A cavern dug under any for tification that it may fink for want of fupport; or, in modern war, that powder may be lodged in it, which being fired at a proper time, whatever is over it may be blown up and deftroyed. What mine hath erft thrown down fo fair a tower? Sidney. -Build up the walls of Jerufalem, which you have broken down, and fill up the mines that you have digged. Whitgift. Others to a city ftrong Lay fiege, encamp'd; by batt'ry, fcale, and mine, Affaulting. Milton. (II.) MINE, in the military art, (§ I. def. 2.) See MINE, II. in laft volume, p. 720. From a great number of experiments, it appears, 1. That the force of a mine is always towards the weakeft fide; fo that the difpofition of the chamber of a mine does not at all contribute to determine this effect. 2. That the quantity of powder must be greater or lefs in proportion to the greater or lefs weight of the bodies to be raised, and to their greater or lefs cohefion; fo that we muft allow for each cubic fathom of loofe earth 9 or 10 lb. Of firm earth and ftrong fand, 11 or 12 lb. Of flat clayey earth, 15 or 16 lb. Of new mafonry, not ftrongly bound, 15 or 20 lb; and of old masonry, well bound, 25 or 30 lb. 3. That the aperture, or entonnoir of a mine, if rightly charged, is a cone, the diameter of whofe VOL. XV. PART 1. MIN bafe is double the height taken from the centre of the mine. 4. That when the mine has been overcharged, its entonnoir is nearly cylindrical, the diameter of the upper extreme not much exceeding that of the chamber. 5. That befides the fhock of the powder against the bodies it takes up, it likewife crushes all the earth that borders upon it, both underneath and fidewife. To charge a mine fo as to have the most advantageous effect, the weight of the matter to be carried must be known; that is, the folidity of a right cone, whose bafe is double the height of the earth over the centre of the mine: thus, having found the folidity of the cone in cubic fathoms, multiply the number of fathoms by the number of pounds of powder neceffary for raifing the matter it contains; and if the cone contains matters of different weights, take a mean weight between them all, always having a regard to their degree of cohesion. As to the difpofition of mines, there is but one general rule, viz. that the fide towards which one would determine the effect be the weakeft; but this varies according to circumftances. The calculation of mines is generally built upon this hypothefis, That the entonnoir of a mine is the fruftum of an inverted cone, whofe altitude is equal to the radius of the excavation of the mine, and the diameter of the whole lesser base is equal to the line of leaft refiftance; and though these fuppofitions are not quite exact, yet the calculations of mines deduced from them have proved fuccessful in practice; for which reafon this calculation fhould be followed till a better and more fimple one be found out. M. De Valliere found that the entonnoir of a mine was a parabaloid, which is a folid generated by the rotation of a femiparabola about its axis; but as the difference between these two is very infignificant in practice, that of the fruf tum of a cone may be used. (III. 1.) MINE, in natural history, (§ II. def. 1.) hplies a deep pit under ground, whence various kinds of minerals are dug out; but is more partiA cularly |