box-sextant

It should be noted that the box-sextant only reads angles in the plane of the instrument, so that if one object sighted is lower than the other, the angle read will be the direct angle between them, and not the horizontal angle, as given by a theodolite.

The Sewerage of Sea Coast Towns Henry C. Adams 1912

To adjust the box-sextant the smoked glass slide should be drawn over the eyepiece, and then, if the sun is sighted, it should appear as a perfect sphere when the vernier is at zero, in whatever position the sextant may be held.

The Sewerage of Sea Coast Towns Henry C. Adams 1912

The general appearance of a box-sextant is as shown in Fig. 42, and an enlarged diagrammatic plan of it is shown in Fig. 43.

The Sewerage of Sea Coast Towns Henry C. Adams 1912

The usual and more accurate method of determining the position of a floating object from the object, itself, or from a boat alongside, is by taking angles with a sextant, or box-sextant, between three fixed points on shore in two operations.

The Sewerage of Sea Coast Towns Henry C. Adams 1912

They bathed and breakfasted in due course, and then, armed to the teeth, set out upon a tour of general inspection, the professor carrying his camera, and Sir Reginald his sketch-block and colour-box, whilst Mildmay and the colonel, provided with a box-sextant and a light measuring chain, set themselves the task of making a rough survey of the ruins and a portion of the surrounding country.

The Log of the Flying Fish A Story of Aerial and Submarine Peril and Adventure Harry Collingwood 1886