Transactions . anteiqDnHLNRiaftlfUANNlIm O* itcnjmru anm&.- ttptf JaJntkr -w/w? tumrf<ul</,,,i xc&ijfoft/jam ?f Octant. Theodolite and Transit. Evolution of the Theodolite.—The German instrument of is illustrated in a curious black-letter book of 38 pages onsurveying;* and, at the time, was considered to be of great * Instrument zur Mechanica, A. Albrecht, 1673. REM UIKS ON MINE 31 i:\ BY] NTG tNSTRl MEN rS. 15 importance. It is possible thai it was employed in mine-sur-veying. In the original description, A is a small compass-box,containing a magnetic needle, with the four cardi
Transactions . anteiqDnHLNRiaftlfUANNlIm O* itcnjmru anm&.- ttptf JaJntkr -w/w? tumrf<ul</,,,i xc&ijfoft/jam ?f Octant. Theodolite and Transit. Evolution of the Theodolite.—The German instrument of is illustrated in a curious black-letter book of 38 pages onsurveying;* and, at the time, was considered to be of great * Instrument zur Mechanica, A. Albrecht, 1673. REM UIKS ON MINE 31 i:\ BY] NTG tNSTRl MEN rS. 15 importance. It is possible thai it was employed in mine-sur-veying. In the original description, A is a small compass-box,containing a magnetic needle, with the four cardinal pointsmarked. B shows an indicator to which the compass-box iescrewed, both of which revolve horizontally. C is a fixedgraduated circle placed under the indicator B, and is divided Fio. i Octant in Use. into 360°; also the four cardinal lines are marked upon it. Dis a circular writing-table placed under the divided circle andextending concentrically beyond it. E is a bound book, partof the instrument, to which all the other parts, previously de-scribed, are firmly attached. The book wTas intended for writ-ing and drawing. FG represents a tube or telescope, attachedby means of a short axis and appendage to the side of the book. h; REMARKS ON MINE-SURVEYING INSTRUMENTS. A vortical semicircle was also fixed to the underside of the tele-BCOpe, and the vertieal angles were indicated by swingingpendulums suspended from the short horizontal axis previouslynoted. NQP represents the upper partofthe stand, with jointsfor giving horizontal motion to the instrument. The cylindri-cal part at N appears to have been divided. When in use, thetelescope of this instrument was directed to an object and theindex bar, B, was then moved by hand round the divided circle, Fig. 145. KALEVIMAG
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Keywords: ., bo, bookcentury1800, bookdecade1870, booksubjectmineralindustries
