* VEGETABLE SUBSTANCES. 



Of the Oak (called Quercus, in Latin) there are 

 fourteen species described by Linnaeus. During the 

 last fifty years, so much attention has been paid to 

 this important tree by travellers distinguished for 

 their researches in natural history, that a surprising 

 addition has been made to the number of known 

 species. Professor Martyn, in his edition of Miller's 

 Gardener's Dictionary, enumerates twenty-six; Will- 

 denow, who wrote in 1805, describes seventy-six; and 

 Persoon, another eminent naturalist of the same date, 

 enumerates eighty-two. At present we have more 

 than a hundred and forty species described by differ- 

 ent writers; and of these more than one half belong 

 to America. Twenty-six species were discovered in 

 North America by two indefatigable naturalists, father 

 and son, named Michaux; and Humboldt and Bon- 

 pland have mentioned twenty-four others, which they 

 found during the course of their travels in South 

 America. Of the various species of oak, some may 

 be classed with shrubs, others with the most majestic 

 trees of the forest; some are evergreens, and others 

 are deciduous, or lose their leaves during the winter. 

 The species from which the best timber is derived, 

 which is by far the most abundant in Britain, and a 

 native of it, is the COMMON OAK (Qucrcus robur.) 



The cut opposite exhibits the leaf, flower, and 

 fruit (the type) of this tree. We shall introduce the 

 same mode of illustration in other instances. 



The oak timber imported from America is much 

 inferior to that of the common oak of England: the 

 oak from the central parts of continental Europe is 

 also inferior, especially in compactness and resistance 

 of cleavage. The knotty oak of England, the " un- 

 wedgeable and gnarled oak," as Shakspeare called it, 

 and in these two words described its leading pro- 

 perties better than all the botanists, when cut 

 down at a proper age, (from fifty to seventy years,} 



