Robert Leffingwell loaned this image of Baltimore & Ohio Mikado No, 315, which he took some time around 1956-57 when the B&O renumbered its remaining steam locomotives to make room for new diesel power. No. 315, formerly 4515, belonged to class Q-3, erected by Baldwin Locomotive Works in 1918 following the USRA light 2-8-2 design. With the 63-inch diameter drivers common to most Mikados, this class had cylinder dimensions of 26x30 inches and sustained a boiler pressure of 200 p.s.i. Locomotive weight was 290,000 pounds. Their grate area was 67 square feet, and their evaporative heating surface totaled 3775 square feet together with 880 square feet of superheating surface. With these dimensions they developed about 54,700 pounds of tractive force. No. 315 is shown here taking on water during what may have been a Chicago area railfan event, judging by the crowd in the background.