Two open mainsprings (without barrels) run the time train, there are winding squares on back for a separate key (instead of screw-on keys). The alarm has a regular mainspring barrel and screw-on key.
Research by Richard Tjarks, Jeff Wood, Gary Biolchini, Greg Adams and Bill Stoddard
Examples of the Westclox Eight Day Alarm Clock:
The movement illustrated is not the one in the clock, but is the same type. The case has no patent date. At the top of the dial is "Pat ... Balance: 1b: Lead rim with notched balance staff.