This rare photo of Chicago & Alton 2-6-6-2 Mallet compound No. 700 comes from the collection of Gary Thompson. The C&A bought three of these locomotives from Alco's Brooks Works in 1910 for coal train and helper service. Apparently Nos. 700-702 were not well suited to the railroad's mostly prairieland profile, and one was shortly resold to the Chesapeake & Ohio. The two others lasted till 1931, when the Alton's Baltimore & Ohio owner took them east and scrapped them. The K-1 class had 62-inch drivers and sustained a boiler pressure of 200 pounds. The rear high-pressure cylinders had dimensions of 22x30 inches, while the front low-pressure cylinders (with slide valves) had a larger diameter of 35 inches but the same stroke of 30 inches. The locomotives weighed 148 tons. Note the arched-window cab and the headlight mounted in the center of the smokebox, unusual for a Mallet articulated which usually had the headlight mounted above the pilot. Photographer, date and location are unknown. For a view of No. 702, also from the Gary Thompson collection, click here.