184 
AMERICAN GEOLOGY. 
frequently vertical, and sunk at a distance from the outcrop of 
the vein so as to intersect it at any given depth which may be 
desirable. To do this it is necessary to ascertain in what direc¬ 
tion and how much the vein dips, or in other words, how many 
feet the vein makes on the dip side in any given number of 
vertical feet. Thus a vein may make to the west seven feet 
horizontally in seventeen vertical feet. It is easy from these 
facts to calculate how far west from the outcrop the shaft must 
be sunk to intersect the vein at one hundred or two hundred 
feet; and so of any other ratio which the vertical plane may 
bear to the inclined one. It is to be borne in mind that a very 
flat vein, as has been already observed, will become steeper as 
it descends. In very flat veins, therefore, calculations of this 
kind can not be relied upon until the vein has reached its maxi¬ 
mum dip. 
Tunnels or drifts are horizontal cuts into the earth or rocks. 
They may be designed both for conveying outwards the mineral 
and for drainage. In that case they are made from the outside, 
or begin on a slope and are worked inwards, or they may pro¬ 
ceed from a shaft to a lode which lies upon one side of it. 
Stoping is a term applied to that kind of work by which the 
vein, or its metal, is removed from its bed. The most econo¬ 
mical way is to stope from beneath upwards. The dead rock 
is readily disposed of, and placed so as to save the expense of 
raising it to the surface, and at the same time aid in supporting 
the walls. The arrangements for stoping should be such that 
several gangs of miners may be employed in taking down the 
vein at different levels at the same time. In this case they will 
be arranged generally in a series of steps, one above another. 
The cost of a shaft seven feet by five, and sixty feet deep will 
not be less than two dollars and a half per foot. If sunk to 
one hundred feet, it will not be less than four dollars per foot. 
A windlass will answer for the purpose of raising rock and 
earth for the first sixty feet, but a whimsey, or whim, is more 
economical below that depth. The apparatus for raising the 
rock and water, however, must depend very much upon cir- 
