Description and Notes:
The initials W. T. G. and the address "Nichols, London" are respectively engraved on the two sides of the folding arms of the compass, but it is not clear whether they corresponding to the maker or the original owner of the compass. The instrument is made of lacquered German silver and steel, the screw topped lead box is made of ivory.
This type of folding compass is considered to be invented by David Napier (1785 - 1873) in 1848, and hence the name. It has been described by W. F. Stanley in his 1878 book, A Descriptive Treatise On Mathematical Drawing Instruments, as
... perhaps the best and most popular kind of pocket compasses, their especial merit being their compact form,
... they are a difficult instrument to make perfectly.
I have acquired a Napier compass by Stanley London also, which is indeed very well made and of the same style and construction as this one, but the size is notably smaller.