126 SEFSTROM ON THE FURROWS WHICH TRAVERSE 
§ 14. 
Some concluding Remarks. 
(A.) Those who would make observations on the furrows should 
be provided with the following instruments :— 
Ist. A small hand-compass, with a square bottom plate, having 
a well-adjusted needle on an agate bearing, which rests on a 
finely pointed pivot which can be often changed. In order that 
this might be done by any one, the pivot should be inserted in a 
hole drilled into a coarser piece, and fastened with shell-lac. On 
the bottom plate there should be a graduated semicircle over 
which a plumb-line can freely traverse, for determining the in- 
clination of the side of the mountain. Two of the sides of the 
bottom plate should be parallel with that diameter of the gradu- 
ated face of the compass which unites 0° with 180°. In making 
observations the compass is placed horizontally, and afterwards 
turned parallel with the furrows the direction of which you wish 
to observe. When the needle, after a gentle tapping on the 
compass, stands still, the number of degrees shown by the 
needle’s north or + end is to be read off, and noted. 
2nd. An azimuth compass, partly for occasionally showing the 
magnetic variation of the needle, partly for determining by it the 
direction of the furrows in places where the magnetic needle is 
disturbed by ore or other causes. 
3rd. A portable leveling-instrument, the telescope of which 
should magnify from ten to sixteen times, and the vernier read 
to fifteen seconds. 
Ath. A graduated measuring tape of 150 feet. 
5th. A good telescope which magnifies above twenty times. 
6th. Two portable barometers, or two Hypsometrical thermo- 
meters of Mohrstadt’s and Gintl’s improved construction. 
In tracts less explored, one should be supplied with,— 
7th. A sextant with an artificial horizon, and a chronometer, 
for the accurate observations of the latitudes, longitudes and 
azimuths. 'The telescope should also be such that occultations _ 
of the stars could be observed with it, as well as eclipses of 
Jupiter’s satellites ; and it should have a stand. 
8th. For investigating the nature of minerals and earthy 
substances, one should be provided with a blow-pipe apparatus, 
as well as the most common reagents. 
(B.) Besides the scientific interest deserving of encourage- 
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