CLASSIFICATION. 353 



portant facts concerning the nationality of the persons. It 

 would appear that the Evans's and Jones's were of Welsh 

 descent, and those whose names bear the prefix Mac of 

 Scotch descent. With the nationality would be more or 

 less strictly correlated many peculiarities of physical con- 

 stitution, language, habits, or mental character. In other 

 cases I have been interested in noticing the empirical 

 inferences which are displayed in the most apparently 

 arbitrary arrangements. If a large register of the names 

 of ships be examined it will often be found that a number 

 of ships bearing the same name were built about the same 

 *time, a correlation due to the occurrence of some striking 

 incident shortly previous to the building of the ships. 

 The age of ships or other structures is usually closely cor- 

 related with their general form, nature of materials, &c. 

 It is impossible to examine the details of some of the 

 most apparently artificial systems of classification of plants, 

 without finding that many of the classes are natural in 

 character. Thus in Tournefort's arrangement, depending 

 almost entirely on the formation of the corolla, we find 

 the natural orders of the Labiatse, Cruciferaa, Rosacese, 

 Umbelliferse, Liliacese, and Papilionacese, recognise! in 

 his 4th, 5th, 6th, yth, pth, and loth classes. Many of the 

 classes in Linnaeus' celebrated sexual system also approxi- 

 mate to natural classes. 



Correlation of Properties. 



Habits and usages of language are always apt to lead 

 us into the error of imagining that when we employ 

 different words we mean different things. In introducing 

 the subject of classification nominally I was careful to 

 draw the reader's attention to the fact that all reasoning 

 and all operations of scientific method really involve 

 classification, though we are accustomed to use the name 



VOL. II. A a 



