It has been shewn that in harmonic combinations of musical sounds, the æsthetic feeling produced by their agreement depends upon the relation they bear to each other with reference to the number of pulsations produced in a given time by the fundamental note of the scale to which they belong; and that the more simply they relate to each other in this way the more perfect the harmony, as in the common chord of the first scale, the relations of whose parts are in the simple ratios of 2:1, 3:2, and 5:4. It is equally consistent with this law, that when applied to form in the composition of an assortment of figures of any kind, their respective proportions should bear a very simple ratio to each other in order that a definite and pleasing harmony may be produced amongst the various parts. Now, this is as effectually done by forming them upon the harmonic divisions of the right angle as musical harmony is produced by sounds resulting from harmonic divisions of a vibratory body. Having in previous works[7] given the requisite illustrations of this fact in full detail, I shall here confine myself to the most simple kind, taking for my first example one of the finest specimens of classical architecture in the world—the front portico of the Parthenon of Athens. The angles which govern the proportions of this beautiful elevation are the following harmonic parts of the right angle— Tonic Dominant Mediant Subtonic Supertonic Angles. Angles. Angles. Angle. Angles. (¹⁄₂) (¹⁄₃) (¹⁄₅) (¹⁄₇) (¹⁄₉) (¹⁄₄) (¹⁄₆) (¹⁄₁₀) (¹⁄₁₈) (¹⁄₈) (¹⁄₁₆) [Sidenote: Plate II.]