Wild Sync   

Production synchronization where the sound recorder and the camera are not linked via time code, a synchronization cable (rare) or crystal speed control. 

Using a slate at the head and tail of each shot, one tries for very short takes and prays often.

If the image recorder's speed is controlled by an exact time source (such as a crystal or 60 Hz alternating current from a wall plug) or is digital (digital video) and the audio recorder is also a digital device (DAT, etc.) then wild sync will work. This is not a preferred method and a head and tail slate is essential.