CONSTRUCTION XVI. FORM OF APERTURE 219

the flat parallelogram sometimes not ungracefully in Italian Renaissance.

§ 13. The question of bevelling becomes a little more complicated in the inlet than the outlook window, because the mass or quantity of light admitted is often of more consequence than its direction, and often vice versā; and the outlook window is supposed to be approachable, which is far from being always the case with windows for light, so that the bevelling which in the outlook window is chiefly to open range of sight, is in the inlet a means not only of admitting the light in greater quantity, but of directing it to the spot on which it is to fall. But, in general, the bevelling of the one window will reverse that of the other; for, first, no natural light will strike on the inlet window from beneath, unless reflected light, which is (I believe) injurious to the health and the sight; and thus, while in the outlook window the outside bevel downwards is essential, in the inlet it would be useless: and the still is to be flat, if the window be on a level with the spot it is to light; and sloped downwards within, if above it. Again, as the brightest rays of light are the steepest, the outside bevel upwards is as essential in the roof of the inlet as it was of small importance in that of the outlook window.

§ 14. On the horizontal section the aperture will expand internally, a somewhat larger number of rays being thus reflected from the jambs; and the aperture being thus the smallest possible outside, this is the favourite military form of inlet window, always found in magnificent development in the thick walls of medięval castles and convents. Its effect is tranquil, but cheerless and dungeon-like in its fullest development, owing to the limitation of the range of sight in the outlook, which, if the window be unapproachable, reduces it to a mere point of light. A modified condition of it, with some combination of the outlook form, is probably the best for domestic buildings in general (which, however, in modern architecture, are unhappily so thin walled, that the outline of the jambs becomes a matter almost of indifference),

[Version 0.04: March 2008]