This photograph gives you a good idea as to how the switch machine inside the the Vernon Interlocking tower would have looked. Each lever would have controlled a switch, switch lock, or signal, hundreds or even thousands of feet away, via a system of rods and cranks running along the tracks. The upper level is only the tip of the iceberg, as the brains of the machine is on the level below, the part of the machine referred to as the interlocking bed. The interlocking bed was "programmed" so that the operator could not create a route for any train that was not clear of a potential collision with another. The entire machine was huge, and the building tself was constructed around the machine.
The photograph is actually the South Norwalk Interlocking Tower, which has been restored, and is a museum, open to the public.
You can visit their website here.