438 REVIEWS 
Perhaps a still clearer example is that of certain mine workings in 
the Newhouse tunnel at Idaho Springs, Colo. This tunnel is driven 
north from South Clear Creek a distance of more than two miles under 
Seaton Mountain and toward Central City. It attains a maximum 
vertical depth of 1,710 feet, or approximately 2,200 feet, as measured 
along the dip of the veins. ‘The slopes of the Gem workings in this 
tunnel are so dusty that there is difficulty in obtaining men who will 
work in them permanently, yet the month that the tunnel cut through 
this vein the men had to wear a full outfit of rubber boots, slickers, 
and rubber hats, and the tunnel drift still yields a notable flow of 
water. When the Addudle vein was cut, approximately .a year ago, 
there was another small flood, and to this day the vein is raining into 
the tunnel steadily. In this instance, despite the steady downpour, the 
old surface workings are as full of water as ever. That the waters 
encountered in the tunnel belong to the ordinary underground circu- 
lation and come from the surface is proven by their oxidizing character. 
In general, along the tunnel the main flow of water comes from the 
veins, but nevertheless there seems to be a minor but steady seepage 
through the country rock. A rough measure of this seepage is given 
by certain work in the Franklin mine. The first of February, this year, 
the sixth level yielded a flow of approximately 7,000 gallons per day. 
Since then the drifts have been extended 250 feet, adding approxi- 
mately 5,000 square feet of surface for seepage, and not intersecting 
any important cross veins or fractures, and yet the flow has slightly. 
more than doubled. Since there has been no corresponding increase 
in the amount of water elsewhere, it seems clear that the larger flow 
is due to the greater surface. The fifth level of this mine, by the way, 
since pumping began on the sixth, is dry, but on the first level there 
is a drift not connected with the lower workings, full of water. Clearly 
in this case the different portions of the vein matter vary greatly as 
regards permeability. Cross-cut tunnels generally yield little water 
except as they intersect fractures; but 1 know of none which does not 
have a water box along the bottom and a steady stream of water flow- 
ing through it; that is, while the flow is practically confined to the 
fractures, the rock, measured in bulk, none the less contains water in 
quantity. The evidence, then, points to a widespread underground cir- 
culation, though there are admittedly dry or impervious beds, and 
admittedly measurable flows are nearly always confined to visible 
cavities. 
