HIS ROYAL HIGHNESS THE DUKE OF SUSSEX, President of the Royal Society, having desired that no unnecessary delay should take place in the publication of the above mentioned treatises, they will appear at short intervals, as they are ready for publication. CONTENTS. [Within the last year or two, several works have been published in this country on subjects more or less closely approaching to that here treated. It may, therefore, be not superfluous to say that the author of the following pages believes that he has not borrowed any of his views or illustrations from recent English writers on Natural Theology.] Page. INTRODUCTION. CHAPTER I. Object of the Present Treatise 13 II. On Laws of Nature 17 III. Mutual Adaptation of Laws of Nature 20 IV. Division of the Subject 23 BOOK I. TERRESTRIAL ADAPTATIONS 25 CHAPTER I. The Length of the Year 28 II. The Length of the Day 37 III. The Mass of the Earth 43 IV. The Magnitude of the Ocean 50 V. The Magnitude of the Atmosphere 51 VI. The Constancy and Variety of Climates 52 VII. The Variety of Organization corresponding to the Variety of Climate 57 VIII. The Constituents of Climate 66 The Laws of Heat with respect to the Earth 67 IX. The Laws of Heat with respect to Water 70 X. The Laws of Heat with respect to Air 81 XI. The Laws of Electricity 91 XII. The Laws of Magnetism 93 XIII. The Properties of Light with regard to Vegetation 94 XIV. Sound 96 XV. The Atmosphere 102 XVI. Light 104 XVII. The Ether 111 XVIII. Recapitulation 113