^36 Siimmaj-y Vicuo qftlie Progress of Gardening, 



with the principle of unity of expression. Each of these classes 

 of materials might make so many different kinds of rockwork, or 

 rather of habitats for the display of plants. To mix all of them, 

 or even any two of them, together is, however, in our eyes, at 

 variance with every principle of good taste. We think it useful 

 to throw out remarks of this kind in this general summary ; 

 because, as we have stated in former volumes, the point in which 

 modern gardeners most require advancement is, the perception 

 of consistency and inconsistency in matters of taste. Temporary 

 glass structures, flued borders, and conservative walls have been 

 mentioned or treated of in different parts of the present Volume ; 

 and, though the subject of growing exotics in the open air by 

 means of such aids is yet in its infancy, it promises to be an 

 inexhaustible source of beauty and interest, as superior to that 

 produced by plants grown in small pots, as a conservatory is to 

 a shed-roofed green-house. 



Arboriculture. — Some years ago, through the exertions of 

 Mr. Lawson, the eminent seedsman of Edinburgh, many thou- 

 sands of Pinus Cembra, raised from seeds imported from Swit- 

 2erland, were planted in different parts of Scotland ; and, what 

 is remarkable, though this tree, in the climate of London, seldom 

 makes shoots above 6 in. or 8 in. in a year, in the neighbourhood 

 of Edinburgh it has made shoots from 1 ft. to 2 ft. annually. A 

 great many larches, raised from seeds received from the Tyrol 

 (see HigJiland Sac. Trans., vol. xi. p. 391.) by Mr. Lawson, 

 have also been planted in Scotland ; and the plants, we are 

 informed, show a deeper green in the foliage than that of plants 

 raised from British seeds. The black pine of Austria, also 

 introduced by Mr. Lawson, has been planted to a considerable 

 extent; more especially by Sir John Nasmyth, at New Posso, in 

 Peeblesshire. Among the most useful exertions that have 

 been made in arboricidture for the last year, and during some 

 years previously, are those of Messrs. Grigor, nurserymen at 

 Elgin and Forres ; who, stimulated by the rewards offered by 

 the Highland Society, have been the means of disseminating 

 many thousand plants of the true Highland pine, by far the 

 most valuable timber tree indigenous or in cultivation in 

 Europe, next to the larch and the oak. It may be worthy of 

 remark, that, of all the ultra-European trees which have been 

 cultivated, in Britain, for such a time as to admit of forming an 

 estimate of the value of their timber, there is not one the timber 

 of which is equal to that of the trees indigenous to Europe. 

 The only shadow^ of an exception is the Populus monilifera, 

 which is a very doubtful native of America, and much more 

 likely, in our opinion, to be an improved Euroj)ean tree. The 

 oaks of America, beautiful as they are, are worth little as timber, 

 either in America or Europe, when compared with the British 



