Pièce 106 - Letter from George Airy

3 pp.

Royal Observatory Greenwich - GA is 'busy in the pendulum reductions, and till they are pretty far advanced or indeed completed we cannot tell how good the results are'. He sent six observers to Haston Colliery: 'I put up the apparatus and gave a few lessons, but I did not take a single observation'. GA gives a description of the tests: 'Galvonic wires were laid from one station to the other, and a telegraph needle was mounted by each clock face, and thus our clocks were compared by simultaneous signals without any necessity for chronometers'. GA is surprised at WW's report of Scoresby's remark on the non-correction of varying inductive force, and he should direct Scoresby [William Scoresby] to look at the Phil. Trans. for 1839 (p. 182-183): 'The effect of induced magnetism is very small, and I believe that ship-correcters very commonly neglect it'.