20 On the Construction of Maps 



a few species, we might adopt some arbitrary sign (see Mr. 

 Hinds's Paper before referred to), composed of parts, any of 

 which could be subtracted at pleasure. Each part should 

 represent a given species, the whole sign representing all the 

 species. On any spot of the map, the whole or part of this 

 sign could be placed, according as all or fewer of the species 

 were known to exist in the locality which it would thus point 

 out. It would be a more simple, although a less precise me- 

 thod, to write the name of each species, within the outline of 

 a common map, in characters extending over a larger or 

 smaller space, according to the actual extension of the species. 

 As the size of the letters must correspond to the space over 

 which the names would be extended, a single glance would, in 

 most, cases teach the prevalent vegetation of a country; a 

 closer inspection becoming necessary to discover its rarer 

 plants, the names of which would be written in small characters 

 at their particular localities ; as we see the names of villages 

 and towns in less conspicuous characters than those used for 

 counties or kingdoms. Unless in the case of particular 

 species of much importance or interest, it could hardly be 

 worth while to attempt any of these methods, as being far too 

 expensive for ordinary publication, and the advantage gained 

 not being equivalent to the cost; since all the information 

 could be conveyed by language alone, assisted by a common 

 geographical map. The superiority of maps over printed 

 pages rests in the former presenting a picture to the sense of 

 sight, all seen at a glance ; whereas words excite only an ima- 

 ginary picture in the mind, often a very imperfect one, and 

 rapidly fading from memory. 



The distribution of orders and genera might be shown ex- 

 actly in the same way as species, by regarding these groups 

 as individuals ; and the plans suggested for depicting the dis- 

 tribution of several species on one map, would be well adapted 

 to exhibit that of orders and their included genera, or of 

 genera and their included species. But these imaginary 

 groups, into which it is found requisite to arrange vegetable 

 forms for the convenience of technical botany, appear to have 

 so little of necessary connection with geography, or even of 

 direct relation to it, that we must be regarded as studying 

 coincidence, rather than dependence and causation, when 

 seeking to connect them. This assertion is at variance with 

 received notions, but I am unaware that it can be disproved. 



It is, of course, altogether otherwise when the general 

 stamp or physiognomy of vegetation, as affected by differ- 

 ences in the climate and physical peculiarities of countries, 

 comes under consideration. Here botany and physical geo- 



