This is a very nice George Jacob Heisely compass, which features two nifty innovations that set it apart from most other compasses.

The first thing that stands out about this compass is the Northern Sight Vane. This sight vane has a unique mechanism that goes up and down the backside of the sight vane, and contains two crossbars that you can see thru the slit of the sight vane. The front of the sight vane has 20 increments (10 - 0 - 10). I assume that these increments are 10 degrees plus or minus. Thus, a surveyor could use this compass to measure vertical angles by raising or lowering the crossbars on the mechanism. Very nifty! See a couple of the pics attached below. you will see that s small screw is missing from the slider mechanism. The absent screw doesn't seem to impact the operation of the mechanism however.

The needle lifter is the second neat innovation that Heisely added to this compass. Most compasses from this era had a thumbscrew that would raise or lower the needle. This compass has a slider mechanism. The slider mechanism is on the underside of the compass and pushes in and pulls away from the center of the compass. (See pic below of the underside of the compass). Very cool! I haven't opened up the compass to see how the slider mechanism works, but it's a very neat device.

George J Heisely was born in 1789, so I suspect that he made this compass in the 1830s, or perhaps in the 1840s. But there is no way to date the compass other than by George's age.

This compass has a 15 inch manipulate and a 6 inch needle. The compass has a very nice eye-pleasing patina. The compass has a chain counter with some darkening on it.

The compass has a small ding on the compass face, as you can see in the last pic posted below. You have to look pretty closely to see it. The ding doesn't detract from the compass much to my eye.

The Compass does not have a face cover, staff adapter or box, unfortunately.

I really like this compass because of the neat features and wonderful patina.

To read more about the Heisely family of makers, please go to my webpage: The Heisely Family