...of which has a vernier at its extremity adapted to the divided circle, and the other a milled-head, d, which turns a pinion, working in a toothed rack...quantity that we can pretend to lay down with certainty. Greater accuracy may perhaps be obtained by the help of a table of natural sines and a well-graduated...

...of the two arms (which form a diameter to the circle) turns a branch, ee, which for packing may he folded over the face of the instrument, but when in...quantity that we can pretend to lay down with certainty. Greater accuracy may perhaps be obtained by the help of a table of natural sines and a well-graduated...

...instrument, but when in use must be placed in the position shown in the figure: these branches cariy, near each of their extremities, a fine steel pricker,...quantity that we can pretend to lay down with certainty. Greater accuracy may perhaps be obtained by the help of a table of natural sines and a well graduated...

...placing the centre of the protractor over the angular point may easily be discovered, for, if incon ectly done, a straight line drawn through the two punctures...quantity that we can pretend to lay down with certainty. Price, $18.00 to $40.00. Fig. 74 Fig. 76. The Pantagraph. — (Fig. 76, as above.) — The pantagraph...

...placed as nearly even with the under surface of the instrument as possible, that no parallax may he occasioned by a space between the lines and the surface...quantity that we can pretend to lay down with certainty. Price, $18.00 to $40.00. Fig. 74. rig. 76. The Pantagraph. — (Fig. 76, as above.) — The pantograph...

...may be folded over the face of the instrument, but when in use must be placed in the position shewn in the figure: these branches carry, near each of...quantity that we can pretend to lay down with certainty. Greater accuracy may perhaps be obtained by the help of a table of natural sines and a well-graduated...

...graduated to single minutes, which, taking into consideration the numerous sources of inaccuracy of this kind of proceeding, is the smallest angular quantity...be preferred to lay down the triangles by means of their sides, beam compasses with vernier scales attached should be used in this operation. The meridian...

...not pass through the angular point, which it will do, if all be correct. MATHEMATICAL INSTRUMENTS. The face of the glass centre-piece, on which the lines...quantity that we can pretend to lay down with certainty. Price, $18.00 to $40.00. Fig. 74. Fig. 75. Fig. 76. The Pantograph. — (Fig. 76, as above.) — The...

...be occasioned by space between the lines on the glasscentre and the surface of the paper. By means of the vernier, the protractor is graduated to single...the numerous sources of inaccuracy in this kind of work, is the smallest angular quantity we can pretend to lay down correctly. It will be barely necessary...