SECT. 13.] Arrangement and Formation of the Series. 41 



scientific sense of the term. It is simply a rule or direction 

 informing us how we may best proceed to treat any group of 

 these errors which may be set before us, so as to extract the 

 true result at which they have been aiming. Clearly there 

 fore it belongs to the inferential or logical part of the subject. 



It cannot indeed be denied that the methods we employ 

 must have some connection with the arrangement of the facts 

 to which they are applied ; but the two things are none the 

 less distinct in their nature, and in this case the connection 

 does not seem at all a necessary one, but at most one of pro 

 priety and convenience. The Method of Least Squares is 

 usually applied, no doubt, to the most familiar and common 

 form of the Law of Error, namely the exponential form with 

 which we have been recently occupied. But other forms of 

 laws of error may exist, and, if they did, the method in 

 question might equally well be applied to them. I am not 

 asserting that it would necessarily be the best method in 

 every case, but it would be a possible one ; indeed we may 

 go further and say, as will be shown in a future chapter, 

 that it would be a good method in almost every case. But 

 its particular merits or demerits do not interfere with its 

 possible employment in every case in which we may choose 

 to resort to it. It will be seen therefore, even from the few 

 remarks that can be made upon the subject here, that the 

 fact that one and the same method is very commonly em 

 ployed with satisfactory results affords little or no proof that 

 the errors to which it is applied must be arranged according 

 to one fixed law. 



13. So much then for the attempt to prove the preva 

 lence, in all cases, of this particular law of divergence. The 

 next point in Quetelet s treatment of the subject which deserves 

 attention as erroneous or confusing, is the doctrine maintained 

 by him and others as to the existence of what he terms a type 



