Barker & Son Singer's Patent Gimbal Compass c.1875 23 Squadron RFC with just some specks of

with just some specks of dust under the glass

but this example is much larger

The plotting scales engraved on the alidade or sight-rule allowed the surveyor to prepare his map with the minimum of calculation

One or two wounded followed – Purdy

Barker & Son Singer's Patent Gimbal Compass c.1875 23 Squadron RFC with just some specks ofA rare Francis Barker & Son Singer's Patent Gimbal compass, dating from c. 1875. The compass is fitted with a gimbal ring and would originally have been mounted in a wooden box for maritime use. The compass bowl is weighted with lead to ensure it was correctly orientated when the gimbals were moving. This is an unusually large example of a Singer's Patent at 68mm diameter most brass cased gimballed Singer's were around 40 45mm. The compass has a paper