Hints to travellers, scientific and general (1901)
Royal Geographical Society (Great Britain) · London, The Royal Geographical Society · leaf 28
nsists of a magnetic needle, A, balanced on a pivot, B, carrying an aluminium ring, C, divided into 360°; it is graduated from the south pole of the needle, — by west, north, and east to south again, from 0° to 360°; the 0° is not shown on the ring, since it coincides with 360°. A prism, D, is… … Prismatic Compass. there is a slit through which the observer looks; it has also an arm with two dark glasses E, to protect the eye when taking a bearing of the sun. On the opposite side of the box is a sight-vane G, having a fine thread down its centre, and a mirror H, which slides on and off as…
