Paper, 'A description of a water level to be fixed to Davis's Quadrant whereby an observation may be taken at sea in thick and hazy weather without seeing the horizon' by Charles Leigh Description of an artificial horizon designed by Leigh to be attached to a Davis's quadrant (John Davis (c.1550–1605)). An addition to aid in navigation at sea when visibility is poor. Includes a figure of the water level in coloured ink. Subject: Navigation / Scientific apparatus and instruments Read to the Royal Society on 3 November 1737 Published in Philosophical Transactions as ' A description of a water-level to be fix'd to Davis's quadrant, whereby an observation may be taken at sea, in thick and hazy weather, without seeing the horizon' [1737]