PREFACE.

vi

attention to other studies had permitted me toacquire. What I wanted, the friendship of myingenious and respectable Colleague, Mr. Playfair,Professor of Mathematics , has supplied , and Ihave been enabled by him to elucidate all thepoints I have mentioned, in a manner which, Iam confident, will afford my Readers completesatisfaction. To him, likewise, I am indebtedfor the construction of two maps necessary forillustrating this Disquisition , which without hisassistance I could not have undertaken.

I have adhered, in this work, to an arrangementI followed in my former compositions, and towhich the Public has been long accustomed. Ihave kept historical narrative as much separate , aspossible from scientific and critical discussions,by reserving the latter for Notes and Illustrations.I flatter myself that I may claim , withoutpresumption, the merit of having examined withdiligence what I submit to public inspection, and ofhaving referred, with scrupulous accuracy, to theauthors from whom I have derived information.

College of Edinburgh,.

May 10th, 1791.