Sewing Machine, U. S. Patent 113,407, April 4, 1871, Alfred S. Dinsmore, Boston, Massachusetts.
This invention is an arrangement of arms and springs that controls the tension of thread in a shuttle-stitch sewing machine. Since the invention is on a production model, it was probably used commercially.
The invention is part of an 18" x 14" x 8" all metal Florence Sewing Machine. The model is painted black with typical sewing machine gold painted decorations. It is in excellent condition and has two partial Patent Office tags.