In all matters of importance, in which the works of previous writers have been used, the sources have been indicated, so that reference to the originals may be made. Upon the celebrated work of Rondelet above mentioned, on many learned articles in the Encyclopédie Méthodique, and on the works of Durand and other esteemed authors, large contributions have been levied; but these citations, it will be observed, appear for the first time in an English dress. In that part of the work which treats of the doctrine of arches, the chief materials, it will be seen, have been borrowed from Rondelet, whose views the author has adopted in preference to those he himself gave to the world many years ago, in a work which passed through several editions. Again, in the section on shadows, the author has not used his own treatise on Sciography. In the one case, he is not ashamed to confess his inferiority in so important a branch of the architect's studies; and in the other, he trusts that matured experience has enabled him to treat the subject in a form likely to be more extensively useful than that of treading in his former steps.

The sciences of which an architect should be cognisant are enumerated by Vitruvius at some length in the opening chapter of his first book. They are, perhaps, a little too much swelled, though the Roman in some measure qualifies the extent to which he would have them carried. "For," he observes, “in such a variety of matters" (the different arts and sciences) “it cannot be supposed that the same person can arrive at excellence in each.” And again: "That architect is sufficiently educated whose general knowledge enables him to give his opinion on any branch when required to do so. Those unto whom nature hath been so bountiful that they are at once geometricians, astronomers, musicians, and skilled in many other arts, go beyond what is required by the architect, and may be properly called mathematicians in the extended sense of that word." Pythius, the architect of the temple of Minerva at Priene, differed, however, from the Augustan architect, inasmuch as he considered it absolutely requisite for an architect to have as accurate a knowledge of all the arts and sciences as is rarely acquired even by a professor devoted exclusively to one.

In a work whose object is to compress within a comparatively restricted space so vast a body of information as is implied in an account of what is known of historical, theoretical, and practical architecture, it is of the highest importance to preserve a distinct and precise arrangement of the subjects, so that they may be presented to the reader in consistent order and unity. Without order and method, indeed, the work, though filled with a large and valuable stock of information, would be but an useless mass of knowledge. In treating the subjects in detail, the alphabet has not been made to perform the function of an index, except in the glossary of the technical terms, which partly serves at the same time the purpose of a dictionary, and that of an index to the principal subjects noticed in the work. The following is a synoptical view of its contents, exhibiting its different parts, and the mode in which they arise from and are dependent on each other.

[A List of the Contents was here inserted.]

Perfection is not attainable in human labour, and the errors and defects of
this work will, doubtless, in due time be pointed out; but as the subject has
occupied the author's mind during a considerable practice, he is inclined to
think that these will not be very abundant. He can truly say that he has
bestowed upon it all the care and energy in his power; and he alone is
responsible for its errors or defects the only assistance he has to acknowledge
being from his son, Mr. John Sebastian Gwilt, by whom the illustrative
drawings were executed. No apology is offered for its appearance, inasmuch
as the want of such a book has been felt by every architect at the beginning
of his career.
Not less is wanted a similar work on Civil Engineering, which
the author has pleasure in stating is about to be shortly supplied by his
friend, Mr. Edward Cresy. [This work has since been published.]

Without deprecating the anger of the critic, or fearing what may be urged
against his work, the author now leaves it to its fate. His attempt has been
for the best, and he says with sincerity,

"Si quid novisti rectius istis
Candidus imperti; si non his utere mecum."

September 30, 1842.

J. G.

ADVERTISEMENT.

GWILT'S ENCYCLOPÆDIA, first published in 1842, has now passed
through eight impressions, those of 1867 and 1876 having received extensive
revision and many important additions at the hands of Mr. Wyatt Papworth.
In this, the ninth impression, besides many requisite amendments and addi-
tions throughout the pages, the chapters entitled MATERIALS USED IN BUILD-
ING and USE OF MATERIALS, which constitute a main portion of the work,
have been largely revised, parts rewritten and added to in important particu-
lars, especially in regard to the details of Fireproof and Sanitary construction,
in order to record the results of later theories and the numerous inventions
introduced since the previous revision. The section SPECIFICATIONS has been
recompiled and enlarged. Several sections of the chapter on PUBLIC AND
PRIVATE BUILDINGS have been withdrawn, and some re-inserted in other por-
tions of the work: a few added revised. The LIVES of eminent Architects
have been brought down to date; as are also the PUBLICATIONS, which have
been partly re-arranged in additional classes; while the GLOSSARY OF TERMS
has been amended where desirable. The INDEX has been carefully revised
to include all new matter.

PATERNOSTER Row: June 1888.