[ 5°5 ] • 
Having laid thefe Accounts before you, permit 
me the Honour to be, 
SIR , 
Catherine Street, June iS. Xour WO^l obeJi nt 
~ ■ 1750. 
humble Servant, 
H. Baker. 
XVIII. A Defer iption of a Mariner ’ s Compafs 
contrived by Gowin Knight, M. B. F.R.S. 
Read July 5.^ ■ 'HE Difcovery of the Mariners Com- 
1750 JL P a ^ s P r °bably been of more ge- 
neral and important Ul'e to human Society, than the 
Invention of any one Inftrument whatfoever : And yet 
fo far have they been from ftudying the Improvement 
of it, that there would be no Abfurdity in fuppofing 
that the firft which was made might be as much fu- 
perior to thofe in common Ufe now, as the mod 
improved Inftrument we have is fuperior to its firft 
Contrivance. 
The Compafs which appeared before this Society 
Lift Year, on account of its being render’d ufelefs by 
Lightning *, was what afforded me the firft Idea of 
their Imperfe&ions, fome of which I then enumerated ; 
but others have fince occurred to me, arifing trom 
the Stru&ure of the Needle, which I had not fuf- 
ficicntly confidered at that time. It was then ob- 
ferved, that almoft all the Compafles on board our 
Merchant- 
* See thefe Tranfaftiont, 492, p. in. 
