302 LIGHT SCIENCE FOR LEISURE HOURS. 



ble results of approaching contests, equine or other- 

 wise. 



Let us take a few simple cases of u odds," to begin 

 with 5 and, having mastered the elements of our sub- 

 ject, proceed to see how cases of greater complexity 

 are to be dealt with. 



Suppose the newspapers inform us that the betting 

 is 2 to 1 against a certain horse for such and such a 

 race, what inference are we to deduce ? To learn this, 

 let us conceive a case in which the true odds against a 

 certain event are as 2 to 1. Suppose there are three 

 balls in a bag, one being white, the others black. 

 Then,. if we draw a ball at random, it is clear that we 

 are twice as likely to draw a black as to draw a white 

 ball. This is technically expressed by saying that the 

 odds are 2 to 1 against drawing a white ball ; or 2 to 1 

 on (that, is in favor of) drawing a black ball. This 

 being understood, it follows that, when the odds are 

 said to be 2 to 1 against a certain horse, we are to infer 

 that, in the opinion of those who have studied the 

 performance of the horse, and compared it with that 

 of the other horses engaged in the race, his chance of 

 winning is equivalent to the chance of drawing one 

 particular ball out of a bag of three balls. 



Observe how this result is obtained : the odds are 2 

 to 1, and the chance of the horse is as that of drawing 

 one ball out of a bag of three three being the sum of 

 the two numbers 2 and 1. This is the method followed 



