Method and apparatus for connecting an upper thread with a lower thread

Method for connecting an upper thread to a lower thread, which comprises inserting the threads into a longitudinal groove formed in a chamber for connecting the threads with a thread feeder being movable from a thread receiving position to a thread delivery position, splicing the threads together in the chamber using compressed air acting on the threads from the side, securely holding the threads up to the application of the compressed air when the threads are inserted into the chamber uncrossed, securely holding the threads which are inserted into the chamber during the splicing in the immediate vicinity of the chamber when the threads are crossed during movement of the thread feeder, elastically pressing the threads against the outer surface of the chamber and wrapping the threads around rims of the groove formed in the chamber at an angle of approximately 90.degree..