1 8 On the Construction of Maps 



cording to their common denominations ; without any detail 

 of physical agents, limits of the extension of genera and species, 

 or any circumstances desired by the naturalist. They seem 

 framed more to meet and please the general reader, than for any 

 benefit for the advancement of science." That the maps 

 hitherto published (at least, such as I have seen) bear the im- 

 press of that imperfection, which marks a newly created depart- 

 ment of science, is too true ; and it is impossible that they can 

 yet exhibit the "limits of the extension of genera and species." 

 But from the sweeping assertion, that they contain merely the 

 names of some plants, without any detail of physical agents, and 

 are calculated chiefly foi the general reader, I must dissent, 

 and most decidedly dissent : for the best maps which I have 

 seen appear to be constructed altogether on the opposite 

 plan ; containing no names of plants ; being almost utterly un- 

 serviceable to the general reader ; and referring chiefly to the 

 physical peculiarities of the countries represented and the 

 climatic distribution of plants within them. In saying that 

 no plants are named in De Candolle's map of French bo- 

 tany, I speak from the memory of some years, and not with 

 any confidence; but Wahlenberg's map of Lapland (Mappa 

 Botanico-geographica), and of the tract of the Carpathians 

 (Mappa Physico-geographica), are now lying before me, and 

 do not exhibit the name of a single plant, except very few 

 (Jour and one) incidentally in marginal explanations. The 

 language in which it is written, I regret to say, prevents me 

 having any knowledge of the work of Schouw; but, judg- 

 ing by the translated extracts which have appeared in the 

 Edinburgh Philosophical Journal, this author also uses colour 

 in lieu of names. There is, however, a chart by Humboldt, 

 in which the distribution of plants is in some degree shown 

 by the position of their names. The same occurs partially in 

 a map accompanying Barton's Lecture on the Geography of 

 Plants. In several instances, also, the altitudinal limits are 

 shown by the names placed at the particular heights in a 

 scale ; but the best botanico-geographical maps yet published I 

 apprehend to be in the works of the three first-named authors. 

 (Such readers as may feel interested in this subject, I beg to 

 refer to Murray's Encyclopedia of Geography, in which is an 

 outline of botanical geography from the pen of Dr. Hooker, 

 embracing a general sketch of the labours of Wahlenberg, De 

 Candolle, Humboldt, and others. A perusal of Mr. Swain- 

 son's remarks on the distribution of birds, in the same work, 

 will repay even the botanist ; because most of the general laws 

 must apply to both, and Mr. Swainson's primary divisions 

 widely differ from those usually taken by botanists.) 



