Coal train and the gravity incline.jpg
H.C. White Co.
en
Coal train and the gravity incline, Steam mining locomotives
commons
en
Coal train and the gravity incline, A loaded coal train and the gravity incline at a coal mine, Pittsburg, Pa., U.S.A.
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ja
石炭列車と重力傾斜角、蒸気機関車
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ja
石炭列車と重力傾斜、A号車と重力傾斜。
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steam coal theory of gravitation gravitational interaction gravitationally gravitation gravity interactional gravitational