I

xiv

Reference has been given to the works fromAvhicli any fact has been obtained, or from whichany opinions have been quoted, in order to thedetection of any errors which may have beenmade. A table of those, which have beendiscovered since these Tracts have been printed,is given in the page following the contents ; andthe reader is requested to correct them by itbefore he proceeds in the perusal of the work.

The author hopes, that these Tracts containenough of new and profitable matter to war-rant their publication, and that they will beaccepted as an earnest of his desire to be usefulto a profession to which he is indebted for muchpleasure and advantage. Tie has now to solicitindulgence from his readers, and to ask themrather to regard those parts of this attempt toelicite the true principles of bridges which havebeen successfully treated, than those respectingwhich he may have failed ; for it has been pur-sued in the intervals of business, and under dif-ficulties which others, in the habitual use of theimplements of knowledge necessary to the en-quiry, might not have experienced.

SAMUEL WARE.

5 . John Street,

Adelphi, London .