Thanks to Kitt for the help ID'ing this.
It might be a theodolite instead of a transit. There seems to be a terminological debate. Here's information from a website Kitt found:
THEODOLITE - Measures horizontal and vertical angles. Its name is one of the most misused in surveying instrument nomenclature, and is used on instruments that not only measure angles, but also directions and distances. There are many kinds, including transit, direction, optical, solar, astronomic, etc.
TRANSIT - For measuring straight lines. Like the theodolite, the transit's name is often misused in defining surveying instruments. Most transits were made to measure horizontal and vertical angles and magnetic and true directions. There are many kinds, including astronomic, solar, optical, vernier, compass, etc.
http://www.surveyhistory.org/intro_to_antique_surveying_instruments.htm
