Levels made for tripods differ from theodolites by lacking a vertical circle, half-circle or arc. From development of William Gravatt’s level in 1830 through the twentieth century, simple leveling telescopes with or without compasses have been called ‘dumpy levels’, referring to Gravatt’s design which had a high diameter to length ratio. They are designed both as simple leveling sights, commonly with a compass or azimuth dial, and as transit levels with a scope that can be rotated to back sight. The original transit level, invented in 1734, was called the ‘Y’ level, because the removable telescope rests on ‘y’ or ‘u’ shaped collars with a similar shaped hinged clip that swings and locks over the telescope to hold it in place. Thus the scope can be easily removed and placed to back site in the opposite direction. From the mid-late-1800s, most transits and transit levels manufactured have been designed with telescopes that swing in the vertical plane forward and backward to back-sight, just like a transiting theodolite. The surveyor’s compass, designed in the mid-1850s, is simply a large, 5 to 6 inch diameter compass in a brass case with hinged sighting alidades, spirit level and vernier scale. Some have interchangeable alidades and telescopes. It usually has a threaded base for mounting to a tripod or staff. Mine dials are similar except later models were more compact, fitted with smaller dials, the vertical dial mounted low against the horizontal dial and equipped with a short telescope sometimes mounted to a gimbaled frame that rotates to offer vertical sightings both up and down.