IN CASES OF LEGAL EVIDENCE. 157 



And for Q, = {/,p, + /,(!- p.^\ Q, + hp,0 - Qi), 



, ^ 99 ,^4 ,^9 j^> 5041 



'^100 '^10 '^lO' '^5043' 



^ , 45500 , 2293 *■ 



which give Q, <t , and Q, Q, <t ; 



* 45992 ^1 ><^ -^ 23, g 



3508 



•5509 



In the following cases, Professor Starkie has assumed that a probability to be conclusive 

 must be indetinite; they are inserted here for the purpose of shewing that conclusiveness is in- 

 dependent of this property. 



Ex. Two pieces of cloth, on being compared, correspond with each other at the junction ; to 

 determine the probability that they were originally one piece. St. 570. n. 



Let the edges be divided into n corresponding portions, and let p, , P2...Pn be the probabilities 

 that any cause, other than the pieces having been originally one, would have produced the corre- 

 spondence of the several portions ; then, it being certain that if they were originally one piece, the 

 edges would correspond. The probability that this is the true cause of the corresponding, is 



, and the conclusiveness of the evidence depends on the smallness of the fraction 



1 + p,.p2...p„ 



p, , p2...p„, and not on the question of its value being or not being accurately determinable. 



For example, if the breadth be 18 inches, and this be divided into as many equal portions, and 



if the values of p,, p2.,.p„ can be accurately assigned, and are each = , then the probability 



that the pieces were originally one, is — — , which is a definite measure. But if, as is prac- 



tically true, it would be difficult or impossible to assign these measures with accuracy, and we can 

 only with certainty define their limits, let p,...p„ be each Ip- — , and <^ , the probability will 



then be <t -^— — > — ^-^^— , and the measure will be indefinite. In either case the evi- 

 1 1 



'"^10^ ' "^ S'" . 10'« 



dence is conclusive; but the probability whose measure is definite, is many thousand times as great 



as the other. 



Ex. ^ is robbed of 1 penny, 2 sixpences, 3 shillings, 4 half-crowns, 5 crowns, 6 half-sovereigns 

 and 7 sovereigns ; B is found in the same fair or market in possession of the same combination of 

 coins. No part of the coin can be identified, and no other circumstances operate against B. 



" Although the circumstances raise a high probability of identity, it is still one of a definite 

 and inconclusive nature." St. ib. 



The hypothesis that B is innocent of the theft is opposed by the extraordinary coincidence of the 

 coins in number and value : the liy])othesis that he is guilty, by the fact, scarcely less extraordinary 

 that there should be guilt which did not afford any other circumstances of suspicion. It is submitted, 

 that the want of conclusiveness is a consequence of the probability that guilt, if it existed, would 

 have left some other evidence of its existence, being as great, or nearly as great, as the probability 

 that the concurring of the coins in number and value was due to their identity. It would further 



x2 



