The Middlebury register. [volume] (Middlebury, Vt.) 1850-1882, 1870-04-26

-" icel through limestone. Slatc ana
coal. The temperature at the bottom was
Is deg. . min. far below the freezing
point. The thickness Of the frozen crust
at Fort Simpson, on Makcnnc's river, in
the same latitute as Yakootsh (62 deg.)
has been found to be &c feet Hours qi
Home far February.
\ New Process for Testing Miurs.
For Il few days past, a novelty, in the
way of steam rock boring machine, for
mining and other purposes, has been at
work in Telegraph Hill, at the end of
Sansome street, north Of Broadway, and
its operation has been witnessed with
much interest by civil engineers, and
practical miners. 1t is small portable
engine, of perhaps five horse power driv-
ing one of Leschot's patent diamond
pointed steam drills This drill was in
vented and patented by Lesehot, the en-
gineer of the Mont Gems tunnel, and per-
fected by Severance * Holt, the latter
being a practical mechanic and is now
put in practical usc for the first time on
the Pacific Coast.
1t is merely a long hollow iron or steel
tube (ron gas pipe is used for ordinary
drilling), with four or FIVE rude bits of
"black diamonds or "carhones." the
coarscst and least valuable formation of
the diamond, set into one end in the edge
Of the metal This pipe Or tube is set
into an apparatus with screw thread for
running it up and down and gcarings for
giving it rapid rotary motion attached
to the engine. The tube or pipe may be
of any required size, from the fraction of
an inch upward. that in use at Telegraph
Hill, is abont two inches in diameter,and
the metal ia about fourth Of an inch in
thickness. When the tube or drill is in
place, it is lowered to the face of the rock
and power being applied is made to rotate
at speed of from four hundred to one
thousand revolutions per minute. The
diamonds set in the end Of the tube cut
n circular trench in the rock as the drill
revolves. leaving n core of solid stone
of the size of the tube less the thickness
of the iron on all sides, in the center, and
as the work progresses, the tube dcscends
steadily into the rock, leaving the core
to run up in the centre, until all the tube
is paved out the machine is then stopp-
ed, the tube elevated and the core dis
charged. This core, it is obvious, must
present an exact sample Of the rock at
every pont. so far as the bore has been
carried down. and an analysis OF il will
show Just what minerals, any have been
cut through. One tube or drill can be
put on TO another, and the boring carried
to any required depth, and if the core nj
any point does not break off and come mp
in the tube, very simple attachment is
let down which cuts it off and brings it
away at once. The machine is so arrang-
ed that it will bore equally well at any
angle, and the rock can be bored at any
point desired, horizontally, perpendicu-
larly, or at any intermediate angle. If
the core is not required for assaying, a
drill making a clear bore like the ordi-
nary drill, but pointed with the black
diamonds can be used in the place Of the
hollow drill, the change requiring but a
moment.
In soft rock like that which Telegraph
Hill is composed Of the hollow will pene-
trate the rock at the rate of four to eight
inches per minute, and in harder rock it
will work equally well, though more slow
ly. On Saturday last a number of repre-
resentatives Of the press saw it at work
upon block of tough blue granite almost
as hard as crystalized quartz, the drill
went through the block of nine inches
in thickness in three minutes and ten
seconds to three minutes and twenty Sec
onds every time, and cut ont core as
clear as a moulded candle. Water is
discharged through the tube all the time
when the drill is revolving so that no heat
is evolved by the friction, and the cutting
of the rock is facilitated. The drill points
Of diamond wear for many months, and
are replaced in few minutes without
trouble. 4 drill of this kind has been
run down over three hundred feet in ma
ny places, and in Colorado near Central
City, one was run in, horizontally four
hundred and seventeen feet and half,
and will be driven four hundred feet fur
thcr to cut a qnartz lead at a great depth
in the mountain. While this invention is
valuable for drilling, for blasting, in the
ordinary manner it promises to work a
revolution in mining in California in
another manner. The great drawback on
on quartz mining is always the cost of do
ing "dead work." that is to say, running
tunnels, sinking shafts, etc. etc,, to pros
pect the vein, or supposed vein, 10 accer-
tain if there is really mineral in it, and
where the deposits lie the mere taking
taking out of the ore when found is but
IA trlfe Now with one Of these machines,
n mine may be prospected in every direc-
ton in few days time, or even in few
hours, at slight cost II costs from eight
to thirty dollars per foot, to sink an or
binary prospecting shaft of five by six feet
in the usual mnnncr, the location of the
district and hardness of rock making the
difference in cost With one Of these
machines il ought not TO cost more than
fifty cents to one dollar per foot to bore
a hole two inches in diameter. taking out
the core for testing. In other words six
teen to fifty such holes can be bored for
what would cost to sink one prospecting
shaft in the ordinary manner. and there
would be no cost for pumping or draining.
The saving in time too is an immense