35 
manner, therefore, in which those who wish to advance our knowledge of 
the geographical botany can employ themselves, is by tracing the range 
of the species, both commoner and rarer, which the county affords ; 
horizontally, by means of the sub-provinces, vice-counties, and subordinate 
districts : vertically, by using the climatic regions and zones, and the lines 
of mean annual temperature, as before explained. I shall be glad at any 
time to receive lists of species observed within any of the districts of 
superior or inferior grade, especially those which make up the north 
riding, and facts respecting the zones which they inhabit, or the eleva- 
tions which they attain. It is only by accumulating details in the first 
instance, and afterwards analysing and comparing them, that we can 
ascend to theconsideration in a satisfactory manner, and finally arrive 
at a correct appreciation of general principles and relations. 
