photographs are taken exactly in front, and no two at just the same angle. Any accurate measurement of such end piers and any comparison of them is out of the question in the present methods of research. One other question may be considered here. Does a series ever occur in which three units are repeated regularly, instead of one or two? In experiments we discovered that the subject found it impossible to feel repetitions of three in a series, and the only way that such a series was tolerable was when the three could be grouped somehow into one or two units. Therefore we should not expect to find such repetitions frequently, if at all. To sum up: Do series always end with a heavier unit? Are units equally distant from each other more adapted to continuous or run-on railings, while units with symmetrical arrangements within themselves are found more often where separateness of objects enclosed is more aimed at than their connection? Is a less heavy end found after symmetrical series than after the other kind? Are repetitions of three units used at all, and if so in what way? Obviously the only illustrations of these questions will be found in the arrangement of posts and pillars in balustrades of whatever description. In these cases alone do we find repeated series, with repetitions within the unit, as well as of the unit as a whole. The following examples have been taken by looking over about one thousand photographs and by recording every instance that occurred. 100 _Examples_ A. 73 Continuous Railings: Balustrades across façades; around roofs; up flights of stairs; around towers and baptisteries. I. 57 Rhythmic Units: a. 31 Even numbers of units in group. Support arches 5. b. 26 Odd number of units in group. 11 Support even number of arches. 6 More than eight units in group. 1 Two sections of railing. Odd number in ends, decoration in centre section to emphasize symmetry. 4 No grouping. Too many to count. 4 Other reasons not assignable. II. 16 Symmetrical units: Slabs with carved reliefs or plain; Carved scroll or diamond designs alternating with posts; Heraldic designs on shields; Conventional decorations in stone or wrought iron.