The Boston & Maine operated 30 2-10-2 or Santa Fe-type locomotives, ponderous engines that were assigned to the railroad's heaviest freight duties before the arrival of the Lima 2-8-4s. The twenty members of the S-1a class are represented here by the first of the group, No. 3000, coming off the turntable at Lowell, Massachusetts on March 18 1935. Weighing in at 377,800 pounds, they exerted 71,251 pounds of tractive force; for other specifications see the commentary for No. 3015 following. This view from an unnamed photographer, provided by Carl Weber, brings out the "reverse" or "indirect" configuration of the Walschaerts valve gear that was applied to these 2-10-2s and many other B&M engines.