N.Y. R.R. Law § 62
Any railroad corporation may contract with any person, association or corporation for the hauling by the special or regular trains of said railroad corporation, the parlor, drawing-room or sleeping car or cars of such person, association or corporation, in which extra accommodations shall be furnished, for which said person, association or corporation furnishing such parlor, drawing-room or sleeping car or cars, may charge for the carriage and transportation of persons and property therein, a reasonable compensation for such extra accommodation, in addition to the fare and charges now allowed by law for the carriage and transportation of passengers and property in the ordinary cars of said railroad corporation. But said railroad corporation so contracting shall be liable in the same way and to the same extent as if the said car or cars were owned by it, and shall furnish sufficient ordinary cars for the reasonable accommodation of the traveling public.
N.Y. R.R. Law § 62