Ingersoll mechanical caliber IN 519. This movement was found in an Ingersoll Chinook model. Chinese-made with 20 jewels. Ingersoll claims this movement should stay accurate between -30 to +30 seconds per day when worn under normal conditions.
According to the Ingersoll manual:
A mechanical watch is a device for keeping time, which uses the energy from a wound spring, and keeps time through the highly regulated release of that energy through a set of gears (the wheel train) and an escapement. It differs from typical quartz watches in that it uses purely mechanical components to keep time. Mechanical watches typically can run for about 40 hours on one full winding of the mainspring.