CONTENTS OE VOLUMES I-VI CLASSIFIED ACCORDING TO SUBJECT PAGE I. MATHEMATICS..... 671 II. GENERAL MECHANICS . . . 672 III. ELASTIC SOLIDS .... 674 IV. CAPILLARITY..... 675 V. HYDRODYNAMICS .... 677 71. SOUND ...... 681 711. THERMODYNAMICS .... 688 7III. DYNAMICAL THEORY OF GASES . . 689 IX. PROPERTIES OF GASES . . . 691 X. ELECTRICITY AND MAGNETISM . . 694 XI. OPTICS...... 700 XII. MISCELLANEOUS . . . . 707 (Note.So much of the classification as relates to 7ols. I.17. is almost identical with the corresponding classification on pp. 569597 of Vol. IV. In the part which relates to 7ols. 7. and VI. the Articles have, on the average, been distributed amongst a somewhat larger number of Subjects than in the earlier classification.)g. The spectrum of the reflected light [in the corresponding optical circumstances] would then show a narrow black band.