According to my Grandfather who toured the observatory in 1936, there was in use there a fixed telescope. An operator would lie on his back and observe the transit (meridian crossing) of stars. Later images show a seated operator at the telescope, it may have been updated at some point. At the moment of the transit, the observer would press a button activating an electrical relay and setting two Riefler chronographs to exact time.
The chronographs were kept in a separate room which only two people were allowed to enter at a time in order to avoid temperature shifts. The room was heated to a constant 81 degrees by dozens of light bulbs all around the room. Each light bulb had an individual thermostat turning it on and off as needed to maintain temperature. To control air pressure, each chronograph was sealed in a glass enclosure connected to an apparatus allowing air to be pumped in or out as needed.. Each clock was mounted on a concrete pier that extended down into the ground 60 feet.
Elgin operated this system until 1958 when technology began finally providing better methods. The observatory structure still exists today at 312 Watch Street, Elgin, Il., just a block of National Street. It is owned by the city and operated by the Elgin school distinct as the Elgin U-46 Planetarium.