Show WHEELS AND PUFFS some information abent a locomotive the number of puffs given by a locomotive always depends upon the circumference cum ference of its driving wheels and the rate of speed at which the engine is for every ono round of the driving wheels a locomotive always gives forth 4 puffs 3 out of each cylinder all such cylinders double the aizo sizo of the driving wheels vary greatly on different patterns of engines they being from 15 to 23 feet in diameter the general run however being 1819 or 20 feet five engines out of every 7 may be set down as having driving wheels 20 feet in diameter the speed of the average express train varies from 54 to 53 miles per hour taking the average circumference of the driving wheel to be 20 feet and the average speed per hour at 50 miles a locomotive will give gainar at express speed puffs per minute or puffs per hour during the same time the wheels will revolve times which will cause the locomotive to give 1050 puffs to the mile therefore an express train going from london to liverpool a distance of miles will throw out puffs be tween the time when it leaves the london depot and that at which it arrives at its destination burins the tourist season of 1888 the journey from london to edinburgh was accomplished in less than 8 hours the distance being miles giving a speed throughout of 50 miles per hour according to the figures shown above a locomotive making such a journey in the time stated must have given forth upwards of puffs or say |