Bk. II. Ch. V. INVENTION OF THE ARCH. 207 early as the times of the pyramid-builders of the 4th dynasty, and was copied in the tombs of Beni Hassan in the 12th ; though it may be that the earliest existing example cannot be dated further back than the first kings of the 18th dynasty; from that time, however, there can be no doubt that it was currently used, not only in Egypt, but also in Ethiopia and Assyria. It would, indeed, be more difficult to account for the fact of such perfect builders as the Egyptians being ignorant of the arch if such were the case ; though, at the same time, it is easy to understand why they should use it so sparingly as they did in their monumental erections. Even in the simplest arch, that formed of only two stones, such as is frequently found in the pyra:>iids, and over the liighest chamber (Woodcut No. 7), it will be evident that any weight placed on the apex has a tendency to lower the summit, and press the lower ends of the stones outwards. Where there was the whole mass of the pyramid to abut against, this was of no consequence, but in a slighter building it would have thrust the walls ajiart, and brought on inevitable ruin. The introduction of a third stone, as in the arch (Woodcut No. 98), hardly remedied this at all, the central stone acting like a wedge to thrust the two others apart ; and even the introduction of 2 more stones, making 5 as in Woodcut No. 102, only dis- tributed the pressure without ,^ r. , ■ ^
-, ^ ^ 102. Arches in the Pyramids at Merol-. (From Hoskms.)
remedymg the detect ; and without the most perfect masonry every additional joint was only an additional source of weakness. This has been felt by the architects of all ages and in all countries: still the advantage of being able to cover large si)aces with small stones or bricks is so great, that many have been Avilling to run the risk ; and all the ingenuity of the Gothic architects of the Middle Ages was applied to overcoming the difficulty. But even the best of their buildings are unstable from tlils cause, and require constant care and attention to keep them from falling. The Indian architects have fallen into the other extreme, refusing to use the arch under any circumstances, and preferring the smallest dimensions and the most crowded interiors, to adopting what they consider so destructive an expedient. As mentioned in the Introduc- tion (page 22), their theory is that " an arch never sleeps," and is con- stantly tending to tear a building to pieces ; and, where aided by earthquakes and the roots of trees, there is only too much truth in their belief. The Egyptians seem to have followed a middle course, using arches
