Incudes an Extra Set of Sight Vanes - Also Includes Rarely Seen Vane with a Slider

This is a very cool William Young Compass. The #3474 serial number dates the compass as circa 1855. The compass is special because it has two rarely seen add-ons. First, the compass includes an extra set of sight vanes, which apparently came with the compass when new. If you look at the compass pic above, you will see the box lid was designed to hold the extra set of vanes. The bottom part of the box also holds two sight vanes. While Young made some 4 vaned compasses, this is not a 4 vaned compass. Compass #3474 can only accommodate 2 vanes at a time.

The second really neat add-on is a sight vane with a slider mechanism attached. Take a look at the last two pics below. The slider likely was used to measure vertical angles to correct the slope distance to horizontal. While many sight vanes have notches on them to aid in this calculation, the slider probably made the calculation easier and more accurate. A neat little rarely seen extra.

The level vial no longer holds liquid, but everything else including the counter seems to work.

The extra sight vanes and the slider vane really set Compass #3474 apart from other mid-19 century compasses, and make this compass very display-worthy. Please feel free to contact me with any questions.