_Height and Head Measurements._--Numerous papers have been published upon height and cephalometry. The object of some has been to compare the less intelligent school children with those who are better endowed. Other authors have taken as their subject the study of asylum or hospital cases. The absence or paucity of results of the earlier studies seems to be due to a cause which we have referred to elsewhere (p. 39). The mistake has been made of judging the intelligence of the children by sole reference to the opinion of the teachers, although account should have been taken of the relationship between the age and the stage of instruction. The comparison between the height and head measurements of the hospital cases and those of school children is not subject to the same risk of error, and striking differences between the two have been noticed. But there is yet another factor which must be taken into account if the figures so obtained are to yield all they are capable of teaching. If one confines oneself to comparing the averages of the two sets of children, one finds them almost identical. We have shown that the only suitable method to use here is the method of arranging the figures in series. This proceeding has suggested to one of us a better method still, that of "frontiers." There is for each age a height limit below which the defectives become clearly more numerous. There are limits in the head diameters, upon each side of which are grouped the abnormally small and the hypertrophied heads, which are frequently associated with mental deficiency. We give here the table which one of us has published of the provisional frontiers for height and for the two cephalic diameters. THE FRONTIERS OF ABNORMALITY (BOYS). ------+--------------+-----------------+--------------+-------------- Age. | Height. | Antero-Posterior| Transverse | Sum of | | Diameter. | Diameter. | Diameters. ------+--------------+-----------------+--------------+-------------- | Centimetres. | Millimetres. | Millimetres. | Millimetres. 6 | 100 | 164 | 134 | 298 7 | 105 | 166 | 135 | 8 | 110 | 169 | 136 | 305 9 | 111 | 171 | 137 | 10 | 120 | 172 | 138 | 310 11 | 124 | 173 | 139 | 12 | 130 | 174 | 140 | 314 13 | 135 | 176 | 141 | 14 | 140 | 178 | 142 | 320 15 | 142.5 | 179 | 143.5 | 16 | 154 | 180 | 145 | 325 17 | 147.5 | 181 | 146 | 18 | 150 | 182 | 147 | 329 ------+--------------+-----------------+--------------+--------------