“ Cars are seldom set apart for exclusive use in moving either class of traffic, but generally are used interchangeably in moving both; and the situation is much the same with trainmen, switchmen, and like employees, for they usually, if not necessarily, have to do with both classes of traffic. Besides, the several trains on the same railroad are not independent in point of movement and safety, but are interdependent; for whatever brings delay or disaster to one, or results in disabling one of its operatives, is calculated to impede the progress and imperil the safety of other trains. ”

“ True, if they were rejected, the two clauses, in the instance of a train composed of many cars, some moving interstate traffic and others moving intrastate traffic, would, by their concurrent operation, bring the entire train within the statute. But it is not necessary to reject them to accomplish this result, for the first clause, with those words in it, does even more; that is to say, it embraces every train on a railroad which is a highway of interstate commerce, without regard to the class of traffic which the cars are moving. ”

“ The two clauses are in no wise antagonistic, but, at most, only redundant; and we perceive no reason for believing that Congress intended that less than full effect should be given to the more comprehensive one, but, on the contrary, good reason for believing otherwise. ”