I built the following circuit and it oscillates at about 1 Hz. I can't figure out however how it works. I picked the design up from an old Bernard Babani book (1979) on 7400 series ICs. The book doesn't explain how it works either. The book uses a 7400 to supply the NOT gates (combining two NAND gate inputs to form a NOT gate). I don't do that, instead I have a transitor based circuit that behaves as a NOT gate. However it oscillates as the book suggested it would. I implemented the circuit in circuitlab and I can get the simulation to show square wave oscillations, see below.
Simulation from circuitlab