When one reflects upon the destructive energy which is contained in a swiftly moving train, and sees its effects in a wreck; when he understands how many minute mechanical details, and how many minds and hands must work together in harmony to insure its safe arrival at its destination, he must marvel at the safety of railroad travel. In the year 1887, the passengers killed in train accidents in the United States were 207; those injured were 916. The employees killed were 406, and injured 890.[20] These were in train accidents only, it must be remembered, and do not include persons killed at crossings, or while trespassing on the track, or employees killed and injured making up trains. As will be seen later, the casualties in these two classes are much greater than those from train accidents. The total passenger movement in 1887 was equal to one passenger travelling 10,570,306,710 miles. That is to say, a passenger might have travelled 51,000,000 miles before being killed, or 12,000,000 miles before being injured. Or he might travel day and night steadily at the rate of 30 miles an hour for 194 years before being killed. Mark Twain would doubtless conclude from this that travelling by rail is much the safest profession that a man could adopt. It is unquestionably true that it is safer than travelling by coach or on horseback, and probably it is safer than any other method of getting over the earth's surface that man has yet contrived, unless it may be by ocean steamer. If one wants anything safer he must walk. * * * * * [Illustration: Stephenson's Steam Driver-brake. Patented 1833.] In considering the means that have been adopted to make railroad travel safe, it must be remembered that there are very few devices in use that are purely safety appliances. Nearly everything used on a railroad has an economic or mechanical value, and if it promotes safety that is but part of its duty. The great source of safety in railroad working is good discipline. Of all the train accidents which have happened in the United States in the last sixteen years, nearly ten per cent. were due to negligence in operation, and seventeen per cent. were unexplained. Of these no doubt many were due to negligence, and many that were attributed to defects of track and equipment would have been prevented, had men done their duty. The value of mechanical appliances for safety is perhaps as often overrated as underrated. Undoubtedly the best, and in the long run the cheapest, practice will be that which combines in the highest degree both elements--disciplined intelligence and perfection of mechanical details. [Illustration: Driver-brake on Modern Locomotive.]