THE FIR TEIBE. 351 



juicy roots run deep into the ground. It is a well-ascer- 

 tained fact in physics, that any given nurober of separate 

 strings will support a much heavier weight than if they 

 were united into one rope. This fact might have been in- 

 ferred from the roots of the Fix-trilie, for being required 

 to resist a greater degree of force than the roots of other 

 trees, they are smaller, and proportionally more numerous; 

 thus being stronger in themselves, and presenting a larger 

 surface of resistance to the surrounding soil, that is to say, 

 being both less liable to snap, and to be torn out from the 

 ground. Moreover, as they extend in aU. directions, they 

 are prepared to resist the violence of the mountain tem- 

 pest, no matter from what quarter it may proceed. 



From the centre of this web of wiry roots rises a stiff 

 column of solid timber, tlie strength of which is not im- 

 paired by being divided into branching arms, but the whole 

 substance is thrown into one trunk ; so that here the least 

 possible amount of surface is exposed to the action of the 

 wind. The Firs, too, are eminently social trees; it rarely 

 happening in the mountains that one stands alone : but 

 though social among themselves, they are strictly exclusive 

 as it regards other trees ; they are generally found cover- 

 ing extensive tracts of country, and being evergreen, they 

 shut out the light from every other tree that attempts to 

 germinate beneath their unfriendly shade. For the most 

 part, they stand as close together as is consistent with 

 their healthy growth; hence they not only borrow from each 

 other a firmer hold of the ground by interlacing their 

 roots, but prevent a free circulation of air round their 

 stems, and consequently the small lateral branches which 

 are formed soon grow sickly and perish. This effect is 

 perhaps increased by the rarefied state of the air at great 

 elevations. The decay of the lateral branches does not, 

 however, in any case extend to the bole, for the dead 

 Avood of the Firs does not rot, as is the case in other trees, 

 but " as soon as vegetation ceases, the consistence of the 

 wood changes ; the sap disappears, and the wood already 



