I have a bobbin like that in my 1900 treadle. hold the shuttle between the thumb and fingers of the lefthand. place the bobbin into the shuttle with the thread drawing toward the right from the side of the bobbin nearest you. place the forefinger on the left hand on the end of the bobbin and draw the thread downward into the long slot in the shuttle as far as it will go. then draw the thread straight upward and under the tension spring until the bobbin begins to unwind. I hope this is as clear as mud