A marine sextant

A study of a marine sextant with an open frame, curved scale, index arm and telescope on textured paper. Construct the open triangular frame and its curved lower arc.

A way into the drawing

1. Establish the construction

   Construct the open triangular frame and its curved lower arc.

2. Resolve the main structure

   Pivot the index arm from the upper joint and place the telescope across the frame.

3. Develop the detail

   Attach mirror housings and the rear handle, then add a few blank arc ticks.

4. Control the values

   Separate overlapping metal parts with dark recesses and narrow reflected highlights.

A small thing to tryKeep the index arm anchored at its pivot rather than floating across the frame.