[79] So, in the exact length or shape of shadows in general, he will often be found quite inaccurate; because the irregularity caused in shadows by the shape of what they fall _on_, as well as what they fall from, renders the law of connection untraceable by the eye or the instinct. The chief _visible_ thing about a shadow is, that it is always of some form which nobody would have thought of; and this visible principle Turner always seizes, sometimes wrongly in calculated fact, but always so rightly as to give more the look of a real shadow than any one else.
§ 1. The reader was, perhaps, surprised by the smallness of the number to which our foregoing analysis reduced Alpine summits bearing an ascertainedly peaked or pyramidal form. He might not be less so if I were to number the very few occasions on which I have seen a true precipice of any considerable height. I mean by a true precipice, one by which a plumb-line will swing clear, or without touching the face of it, if suspended from a point a foot or two beyond the brow. Not only are perfect precipices of this kind very rare, but even imperfect precipices, which often produce upon the eye as majestic an impression as if they were vertical, are nearly always curiously low in proportion to the general mass of the hills to which they belong. They are for the most part small steps or rents in large surfaces of mountain, and mingled by Nature among her softer forms, as cautiously and sparingly as the utmost exertion of his voice is, by a great speaker, with his tones of gentleness.
§ 2. Precipices, in the large plurality of cases, consist of the edge of a bed of rock, sharply fractured, in the manner already explained in Chap. XII., and are represented, in their connection with aiguilles and crests, by _c_, in Fig. 42, p. 195. When the bed of rock slopes backwards from the edge, as _a_, Fig. 73, a condition of precipice is obtained more or less peaked, very safe, and very grand.[80] When the beds are horizontal, _b_, the precipice is steeper, more dangerous, but much less impressive. When the beds slope towards the precipice, the front of it overhangs, and the noblest effect is obtained which is possible in mountain forms of this kind.