TRAVELING AT HIGH SPEEDS HEL-E-SHAW. 641 



the population increases and there is less room for everybody, the 

 question of brakepower becomes more and more important, and 

 with it, of course, the power of starting from rest quickly, or, to put 

 it in scientific words, the power of rapidly effecting both positive 

 and negative acceleration. We are very differently constructed from 

 the particles of air in which we live, and do not yet travel as fast, 

 but fortunately, as yet, we are not quite so crowded, since, according 

 to Lord Kelvin, they move about amongst each other at the ordinary 

 atmospheric temperature and pressure at an average speed of 1,800 

 miles an hour, and they can not avoid fewer than 5,000 million col- 

 lisions in every second. As you see in the streets, and as I shall 

 show you with regard to suburban traffic, high speed is becoming 

 more and more a question of starting and stopping rapidly. I 

 remember in the early days of cycle racing, in order, to lighten the 

 machine, the racing men had no brake, until they found what is now 

 well recognized — that the speed at which you can travel depends 

 upon the safe distance in which you can stop. I can illustrate this 

 by dropping an egg from the dome of this building, which I can do 

 without causing it any injury, even when it is traveling at 30 miles 

 an hour, if I have proper means for bringing it to rest. I also drop 

 a wineglass from the same height and bring it to rest quite safely. 



Owing largely to the perfection of the continuous brake, the speed 

 records obtained on several railways are from 96 to 98 miles an hour, 

 winch I have put down on the diagram, and it is possible that 100 

 miles an hour has been reached, and even exceeded; but this is a very 

 different matter from the highest express running which is found 

 really practicable. You will see on the speed chart (fig. 3) a line 

 indicating the average railway speeds of the fastest running (without 

 stopping) for the 15 principal railways of the country. The average 

 distance of the quick runs is 51.7 miles, and the average fastest run- 

 ning is 56.2 miles per hour. On either side of this line are the two 

 fastest speeds namely, 61 1 miles per hour for 44^ miles on the North- 

 eastern Railway from Darlington to York, and the lowest of these is 

 51 miles an hour, over the 51 miles from Victoria to Brighton on the 

 London, Brighton & South Coast Railway. This shows how little 

 the high speeds of all the railways of tins country differ from one 

 another, and indicates, at any rate for the present conditions, the 

 highest speeds of traveling found suitable to our wants. 



I will take as another illustration of actual traveling the case of 

 suburban traffic; and we have only time for one example, namely, 

 the traffic from the Mansion House to Ealing on the Metropolitar 

 & District Railway, the details of which have been kindly provided. 

 by Mr. Blake, the superintendent of the line. Figure 5 shows in 

 38734°— sm 1911 41 



