further to my last comment after more research i have realised that i got the patent date wrong, edward massey was born in the early 1800s(1802 i think) and went on to patent his so called harpoon log in 1863ish a few years prior to the development of the walkers of birmingham england log of a very similar design.

this is in fact as knackler states a ships log although not a walkers model.i also own a walkers a2 harpoon log and althaugh very similar it is my opinion a massey ships log patented aprox 1806 that we see here.the first mechanical shis log ever patented..