. Our iron roads: their history, construction and administration . can lines have remarkable character-istics of their own. Some of these are plainly indicated in theaccompanying engraving. OUR IRON ROADS. It is difficult to understand the speed not only at whichsal Structures travel, but at which some of their parts areworking. When, for instance, a train is running at 50 miles anhour, the pistons are passing backwards and forwards alongthe cylinders at the marvellous rate of 800 feet a minute,and the movements of some parts of the machinery are dis-tinctly and regularly dividing even a secon
. Our iron roads: their history, construction and administration . can lines have remarkable character-istics of their own. Some of these are plainly indicated in theaccompanying engraving. OUR IRON ROADS. It is difficult to understand the speed not only at whichsal Structures travel, but at which some of their parts areworking. When, for instance, a train is running at 50 miles anhour, the pistons are passing backwards and forwards alongthe cylinders at the marvellous rate of 800 feet a minute,and the movements of some parts of the machinery are dis-tinctly and regularly dividing even a second into many equalparts When a train is running at 70 miles an hour, a space istraversed of about 105 feet per second—that is to say, thirty -five yards between the tickings of the clock. If two trains passone another at this speed, the relative velocity will, of course, bedoubled ; so that, if one of them be seventy yards long, it wouldRash past the other in a second. Now, according to the experi-ments of Dr. Hutton, the flight of a cannon-ball, having a range. AN AMERICAN LOCOMOTIVE. of 6,700 feet, takes a quarter of a minute, which is at the rate offive miles a minute, or 300 miles an hour; and hence it follows,that a railway train moving at 75 miles an hour has one-fourthof the velocity of a cannon-ball, and is practically a huge projec-tile, subject to exactly the same laws as projectiles, and havingthe same force as projectiles ; only that a cannon-ball weighsperhaps 100 pounds, and a train may weigh 100 tons. Thisforce, like that of a cannon-ball, is estimable as the weight ofthe body multiplied by the square of its velocity, and the blowwhich the oscillations of an engine cause to be given to the railsarc comparable with the impact of a rifle bolt upon an irontarget. In gunnery practice the tests are generally applieddirect, in railway battering the blows are indirect. The gun-shot hitting on an incline does not penetrate, but makes a more THE WORK OF ENGINES. 337 or l
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectrailroa, bookyear1883
