Correspondence and papers concerning refinements and improvements to chronometers, including B. Russell's new escapements, with drawings; J.V. Weber's plan for equalising tension in the main spring, with plans; trials of J.M. Bloxam's gravity clock escapements; J.E. Merritt's compensating pendulum; E.T. Loseby's improvements in clocks, with plans and a description of the Leicester Exchange Clock; S. May's new chronometer balance; J.R. Hall's patent for improved clocks and watches; a hermetic case tested by J. Washington; C. Frodsham's trials of chronometers; M.J. Johnson's magnetic dispenser; and claims by J.G. Ulrich for rewards for his chronometers.