PREFACE,

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portunities of information, should enable me; appeared tobe the most: rational and direct means, not only of esta-blishing solid principles of the several arts as now exer-cised, but of procuring an useful intercourse and communi-cation of knowledge, of supplying many of their defects,of multiplying their resources, of improving their pro-ducts, of facilitating and simplifying some complex ope-rations, and rejecting useless ingredients in sundry com-positions, of enriching one art with the practices, mate-rials, and sometimes even with the refuse-inatters ofanother.

Such therefore is the plan which I have chosen to fol-low, and of this alteration I gave notice in an advertise-ment in 1761.

I have the satisfaction to find that the French academyof sciences, who, with the advantage of pensions from thesovereign, and with the assistance of experienced artists indifferent professions, have been engaged for near a centuryin a history of arts which has but lately been begun to bepublished, express exactly the same sentiments with thoseon which I have proceeded. In the memoirs for 1763,the historian of the academy, in giving notice of the pub-lication of that work, observes that “ an inconvenienceto be feared is, the want of that knowledge, and of thosegeneral principles, which bind arts as it were together, andestablish between them a reciprocal communication oflight. All the arts, for example, that employ iron, havecommon principles, but it would be in vain to expect theknowledge thereof from those who exercise these arts,

b 2 each