Computations and calculations for the altitude and azimuth instruments, including examinations of the pivots and graduations of the vertical and horizontal circle in the instrument; intervals of wires; comparisons of the levels to the plane and axis of the vertical circle; computation of zenith distances and tabular errors; alterations to the azimuth instruments, with a description; and plans of the instrument drawn on canvas. There is also brief correspondence with Sir F. Beaufort and J.C. Hare and an engraving of a lighthouse and seed drill.