being respectively, in the order of the table 2ôñ36, 2ôñ24, 2ôñ18, and 2ôñ17. But this evidently amounts to no more than an empirical rule; for we can easily see that it depends on the particular scale which we have used, and that if the weights had been taken, for instance, in kilogrammes or in milligrammes, the agreement or coincidence would not have occurred45. {93}
| Age | Men | Women | ||||
|---|---|---|---|---|---|---|
| Total height m. | Head m. | Ratio | Height m. | Headã m. | Ratio | |
| ãBirth | 0ôñ500 | 0ôñ111 | 4ôñ50 | 0ôñ494 | 0ôñ111 | 4ôñ45 |
| ã1ô year | 0ôñ698 | 0ôñ154 | 4ôñ53 | 0ôñ690 | 0ôñ154 | 4ôñ48 |
| ã2ô years | 0ôñ791 | 0ôñ173 | 4ôñ57 | 0ôñ781 | 0ôñ172 | 4ôñ54 |
| ã3ô years | 0ôñ864 | 0ôñ182 | 4ôñ74 | 0ôñ854 | 0ôñ180 | 4ôñ74 |
| ã5ô years | 0ôñ987 | 0ôñ192 | 5ôñ14 | 0ôñ974 | 0ôñ188 | 5ôñ18 |
| 10ô years | 1ôñ273 | 0ôñ205 | 6ôñ21 | 1ôñ249 | 0ôñ201 | 6ôñ21 |
| 15ô years | 1ôñ513 | 0ôñ215 | 7ôñ04 | 1ôñ488 | 0ôñ213 | 6ôñ99 |
| 20ô years | 1ôñ669 | 0ôñ227 | 7ôñ35 | 1ôñ574 | 0ôñ220 | 7ôñ15 |
| 30ô years | 1ôñ686 | 0ôñ228 | 7ôñ39 | 1ôñ580 | 0ôñ221 | 7ôñ15 |
| 40ô years | 1ôñ686 | 0ôñ228 | 7ôñ39 | 1ôñ580 | 0ôñ221 | 7ôñ15 |
ã A smooth curve, very similar to this, for the growth in ãauricular heightã of the girlãs head, is given by Pearson, in Biometrika, III, p. 141. 1904.
As regards external form, very similar differences exist, which however we must express in terms not of weight but of length. Thus the annexed table shews the changing ratios of the vertical length of the head to the entire stature; and while this ratio constantly diminishes, it will be seen that the rate of change is greatest (or the coefficient of acceleration highest)