TRANSLATOR’S PREFACE. It is now upwards of seventeen years since this treatise, the only publication in which the celebrated Professor of Frey berg has given any exposition of the principles of his theory, wa§ first presented to the public : yet strange as it may appear, it is no less true, that the doctrine it contains has been almost unknown, at least little studied, in this country, till within these very few years. It would be no difficult matter to adduce a variety of reasons in explanation of this singu lar circumstance ; but such a detail would be very uninteresting. Nothing perhaps has re tarded a knowledge of the valuable observa tions and discoveries which it contains, more than