View of an advertising card for L. Black & Co. Printed on front: "L. Black & Co., opticians, manufacturers of spectacles and eye-glasses, in steel, silver, gold and rubber frame, 77 Woodward Avenue, Detroit, Mich. Importers of optical and mathematical instruments. Sole agents for Mueller's celebrated artificial human eyes." Printed on back: "Coldest days in 11 years as observed by L. Black & co., opticians, 77 Woodward Ave." with list of dates and temperatures.