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oblique veins, are frequently heaved or thrown from 
their course, and often otherwise affected. The heave 
or throw is generally found to be oil the side of the 
oblique angle, formed by the intersecting planes of the 
converging veins. Cases to the contrary have, however, 
occurred, and at the Grassington mines one exception to the 
rule took place, where the vein was heaved to the acute 
angle, and lengthened about fifty yards. This dislocation 
of veins is indicative of different periods of vein-formation. 
When one or both veins produce ore up to the point at 
which they meet, the yield is mostly increased by their junction. 
The extent of the angle formed by the two veins is, however, 
in the miner's mind, indicative of the result — the more acute 
the angle, the greater the chance of a deposit. 
The greater portion of the produce of the northern 
district is from the Old Gang Mine in Arkendale, and Kell 
Head in Swaledale ; while the Grassington Mines, in 
Wharfedale, yield about two-thirds of the produce from 
the southern fields. 
From what has been briefly advanced, it will be noted, 
that mining for metallic minerals is of a much more uncertain 
and speculative character than that for coal ; and further, 
that lead mining in stratified districts is attended with greater 
difficulties and uncertainties than in the more Primitive rocks. 
It must not be supposed that in any lead mining district 
the veins are continually productive ; since the best bearing 
lodes have often great lengths of unproductive ground. 
In all mining districts, especially in a stratified country, 
the phenomena presented by veins, their frequent heaves 
and dislocations, and their varied appearances when bounded 
by different rocks, call for very close attention ; and even a 
dependence on knowledge acquired in one district may prove 
fatal in another. The miner should be perfectly acquainted 
with the nature of those substances which it is his daily task to 
