The adoption of automatic couplers was stimulated in some degree by laws enacted by the various states and by the United States; and the Safety Appliance Act passed by Congress in 1893 made it unlawful for railways to permit to be hauled on their lines after the ist of January 1898 any car used for interstate commerce that was not equipped with couplers which coupled automatically by impact, and which could be uncoupled without the necessity for men going in between the ends of the cars.