Locomotives like the Ariel and New York Elevated 39 shown were called Forney type locomotives after the 1866 patent of M. N. Forney, a renowned locomotive expert of the time. Forney types were well adapted to light passenger service. The New York elevated lines used hundreds of these little machines before adopting electricity in the early years of this century. The No. 39 was built by Baldwin in 1878. (Recent Locomotives, Fig. 92)