Wheeler and Wilson D12 twin-needle lock-stitch sewing machine, 1890.

This machine was built by the Wheeler and Wilson Manufacturing Company in 1890 and was intended for fancy stitching on leather. It has two needles mounted on a single needle bar, their threads carried by a rotating hook around a single bobbin, so that two parallel seems connected by the underthread can be sewn simultaneously. Its variable speed motion was designed to improve the appearance of the stitch. In 1905 the Wheeler and Wilson Manufacturing Company, which until 1870 had been the largest manufacturer of sewing machines, was taken over by the Singer Manufacturing Company.