Item 117 - Letter from George Airy

Flamsteed House, Greenwich - GA has been laboring on the account of Sheepshanks's [Richard Sheepshanks] work on Standards, which has now passed through its first stage. GA's plan devised for the Correction of the Compass is adopted by most iron ships in the world. However, the Admiralty 'nominally adopt Archibald Smith's mode of resolving observed errors into series &c of multiples and then computing errors generally, but practically, I do not think it is ever used at all'. GA gives a description of 'a very neat way of presenting errors graphically, which was invented by Napier [Robert Napier], iron ship builder, of Glasgow'. GA had a Royal Navy ship sent out with a corrected compass last autumn: 'Scoresby [William Scoresby] had not published any thing specific. Changes were found in the magnetism of the ship. Some of his compass observations came to me through the Liverpool Committee [of the BAAS], and I discussed them. A very valuable report on the subject generally, including these, has been made by the Liverpool Committee to the B. of Trade, which I have urged the Board to publish'. GA does not know anything of the diurnal variations and the magnetic storms, as compared with solar spots.