Elgin Grade 101

This is a less common Elgin Watch Company product, the lever-set grade 101. It is a 6 size, 11 jewel, design, this one made about 1890.  

If you look close, you can see that the movement has a male stem, and the case has a square hole to match that in the arbor inside the neck of the case. This is a less common case/movement design in vintage American pocketwatches. Cases of this style are quite rare.