The male and the female, from which the bobbin moves this way and that, must be square, so that everything can turn at one time together with the spinning-wheel; otherwise it would not run well.

a, n

Just as here the thread a n, having come out of its bobbin, is bent, so one can bend the cord of the spinning-wheel and send the line of the carriage's spindle along the line of the thread a n.

The thread a n that is to be twisted must, when it first begins to be gathered onto its bobbin, already be very well twisted. For you must consider that if the thread gathered in one whole turn onto the bobbin a were 1/3 of a braccio, and the span between a n — that is, the length of thread being twisted — were one braccio, and this thread were not twisted at all, and as soon as you turned the spinning-wheel that bobbin began to gather that poorly twisted thread, the thread would always keep that same twist and would never be well twisted. Hence you must hold the head of the thread a in your hand and give three turns to the spinning-wheel, so that with each turn the thread receives a hundred twists, that is for every third of a braccio. So, the thread a n being, as said, three thirds of a braccio, it will have 300 twists from the 3 turns given by the spinning-wheel. This done, stop, attach the thread to the bobbin, and continue to the very end, and it will come out well. And if you want the thread more or less twisted, arrange it as you please between a n, for it will always continue in the manner you set there.