1884. J on Bicycles and Tricycles in Tlieory and in Practice. 



17 



wear of only ^^- inch off tlie surface. At this rate of wear — 

 3-12 mgms. per 1000 miles — tbe balls would lose only J- of their 

 weight in travelling as far as from here to the moon. 



The twelve balls, after the first 200 miles, each weighed in grammes 

 as follows. The loss of each in running 600 miles is appended ; — 



miles. 



I did not weigh each ball on the first and last occasion ; however, 

 the wonderfully uniform wear in the intermediate 600 miles speaks 

 well for the equal hardness of the balls. 



The wear of the dozen during each journey of 200 miles was as 

 follows : — 



I have given the results of these experiments at length, for I do 

 not think that accurate and systematic observations of the kind have 

 been made before. 



We may consider, then, that the balls are practically inde- 

 structible. Knowing this, Mr. Trigwell has applied the ball bearing 

 to the construction of the " head " of the bicycle, not so much with the 

 view of diminishing the friction there, but of preventing wear in a 

 place where any shake is highly objectionable. One of his ball 

 heads is en the table. 



The frame of the bicycle, consisting merely of the fork and Lack- 

 bone, is made of thin steel tube, the type of all that is light and 

 strong, Indiarubber, besides being used for the tyres of all machines, 

 has been worked into every part of the structure, to diminish, so far 

 as is possible, that perpetual and wearying vibration of which all 

 bicyclists so bitterly complain. The number of improvements in 

 every detail is so great that any attempt to enumerate them is out of 

 the question. Suf&ce it to say that the modern bicycle is the per- 

 fection of all that is perfect ; as a machine for racing, as a machine 

 for hurrying over good and level roads, nothing can approach it. 

 Unfortunately, however, there is ever present danger, and danger of 

 the most objectionable sort, for the most skilful rider knows too well 

 that should he strike a stone of even an ordinary size, he must expect 

 to be pitched over the handles and come with a crash to the ground. 



Vol. XI. (No. 78.) o 



