PREFACE. vii 
countries, usually seen in green-houses or conservatories, appear in a flourish- 
ing state in the open air; and also because the culture and management of 
such plants call forth a higher degree of scientific knowledge and attention 
on the part of the gardener, and therefore contribute to his improvement and 
consequent usefulness. Half-hardy trees and shrubs of the more tender kinds 
are generally cultivated against what is in this Work called a conservative wall ; 
that is,a wall which may be flued or not according to circumstances, but which 
admits of putting up a temporary projecting roof, or some other means of 
protection, during the winter season. Such walls are at present not very 
generally in use for ornamental exotics; but so great are the interest and 
beauty which they are calculated to display when properly designed, planted, 
and managed, that in a few years they will probably be as general as fruit 
walls; and, as ornaments to a country residence, connected with the flower- 
garden and shrubbery, will be considered as ranking next to the conservatory 
and the green-house. 
Having given this notice of the objects which have led to the undertaking 
of this Work, and a general outline of the plan pursued in it, the reader is 
referred to the Introduction, and to the Explanatory References which pre- 
cede the Table of Contents, for further details. 
The engraving and printing of this Work, for which collections had been 
making for several years (see the Gardener’s Magazine, vol. vi., for 1830, 
p. 582. and p. 718.), was begun in August, 1834 ; and it has been published in 
Numbers, the first of which appeared in January, 1835, and the 62d and 
last on the Ist of July, 1838. It was originally intended to include in 
it a generalisation of the whole subject of the trees and shrubs of temperate 
climates; but, finding the Work had increased to more than double the 
extent originally contemplated, it has been thought advisable to publish the 
generalisation alluded to separately ; and it will accordingly appear at some 
future time, in one volume, under the title of an Encyclopedia of Arboriculture. 
It now remains for the author to acknowledge his obligations to the nu- 
merous persons who have given him information for this Work. He refers to 
the List of Contributors, p. xv., and to every individual there named he begs 
to return his most sincere thanks. He thanks, in a more particular manner, 
the Council of the Horticultural Society of London, for having granted him 
permission to take portraits of the trees in the Society’s Garden, and to ex~ 
amine and make drawings from the botanical specimens sent home by Douglas 
and others, in their herbarium ; as well as for the information communicated 
by their head gardener, Mr. Munro, and the foreman of theirarboretum, Mr. 
Gordon. The author is deeply indebted to Messrs. Loddiges, with reference to 
their arboretum at Hackney, and for the kind and liberal manner in which they 
have at all times, during the last ten years, since he began to prepare for this 
Work, not only allowed him to send artists to make drawings, and supplied 
him with specimens, but permitted him to select these himself; and, in short, 
to use their unrivalled collection of hardy trees and shrubs as if it had been 
his own. To the Linnean Society, and their librarian, Professor Don, the 
author is much indebted for the loan of books, and for permission to examine 
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