403 
the mechanism: of bicycles. 
ensure each number always appearing in the centre of the aperture. 
The “ Veeder - ” cyclo¬ 
meter is on a somewhat 
different principle, the 
various figures being 
printed on the rims of 
discs which all rotate 
about the same axis. 
Tbe star wheel is^on 
the eccentric spindle! of 
a double spur wheel, i.e. 
two spur wheels (having 
19 and 20 teeth respec¬ 
tively) keyed together ; 
the 19 toothed wheel 
gears with an annular 
wheel (of 22 teeth) fixed 
to the frame of the 
cyclometer, the 20 
toothed wheel gears with 
Diagram “ D. 1”—Tlie Veeder Cyclometer . an annu l ar wheel (of 23 
teeth) on the inside of the “ fraction ” disc, which has to revolve 
once for each mile travelled . 1 
This combination forms an epicyclic train, the value of which can 
be worked out by the usual formula . 2 
On the “ fraction disc is a projection which, on the completion of one 
revolution, comes into contact with a small double four armed star 
wheel which gears with the teeth (ten in number) on the annular 
wheel of the unit disc, which is consequently moved one tenth of a 
revolution for each mile; the “ tens 99 orhundreds 99 discs are provided 
for in a similar manner. Yery delicate springs prevent each disc 
being moved through more than the correct distance and hold the 
discs steady in position. 
To explain the working of the epicyclic train without using the 
formula it may be taken in this way. 
The small spur wheel has 19 teeth and consequently when the eccen¬ 
tric spindle has rotated once it has moved a distance equal to 
the pitch of three teeth (in the opposite direction) with relation to the 
fixed wheel, since 22 — 19=3, and therefore it will take ^ or 63 - revol¬ 
utions of the spindle for the spur wheel to rotate once round the eccen¬ 
tric spindle. The larger spur wheel in the same way having 20 
teeth and the fraction disc 23, the same thing happens that is to say 
it moves back 3 teeth for each revolution of the eccentric spindle 
—but now it is seen that it will take 6 f ( 2 ? °) revolutions of the spindle 
for the larger spur wheel to rotate once round the spindle and only 
1 A large working model of this cyclometer showing the mechanism was exhibited. 
2 JE = ff x f§ = 1-07. 
-p _ M — A _ 0 — 145-7 145-7 _ 1-n? 
N — A 1 — 145-7 “ 144-7 
