SLIDES.

When a lode has been thrown up by a slide, to find the base and perpendicular.

Rule. Add the bases made by the segments of the lode together for the horizontal, and subtract the perpendicular made by the ascension of the slide from the sum of the others for the perpendicular.

EXAMPLE.

A shaft having been sunk on a lode 114 feet from A to B, on an angle of 54° 30', at this place the lode was separated and thrown up by a slide, from B to C, 32 feet, the angle of elevation at B being 47°: at C the lode was again cut and prosecuted on an angle of 51°, from C to D, 73 feet. Required to know the length from A to E at surface, where a perpendicular shaft should be put down, that would intercept the lode at the foot of the diagonal C D; also the depth of the shaft E D.

NOTE-Perpendiculars to strike B or C and their respective horizontal distances from A are shown by the sums of the first and second operation in the above calculations.

When a lode has been thrown down by a slide.

Rule. Add the perpendiculars together for the depth, and subtract the base of the slide from the bases of the segment of the lode for the horizontal.

EXAMPLE.

A shaft A B having been sunk 77 feet on a lode which made an angle of 34° 45', it was there found that a slide had severed

B

or disjoined the lode and carried it downward from B to C 40 feet, on an angle of depression or declivity 59°. Here (at C) the lode was again discovered, and wrought 102 feet from C to D, on an angle of 42° 15′; required the depth of the vertical line D E, and the length of the horizontal A E.

NOTE.-Should it be required to find the proper depth in the shaft D E from whence to drive a cross-cut to strike the end of the shaft A B, (where the slide first appeared,)—the perpendicular of the first draft gives the depth, and the length of the cross-cut will be found by subtracting the

base of the first draft from the horizontal line A E: and should it be necessary to make a drift from the shaft D E to the angle C, (where the lode was again discovered,) the depth will be found by adding the perpendiculars of A and B together, and the bases of B and C will be the length of the drift.