(c.) Breadth of Head of Honours Men.
| Honours. | Under 6″ ·05. | Over 6″ ·05. | Totals. |
| 1st class | 58 | 95 | 153 |
| 2nd class | 95 | 87 | 182 |
| 3rd class | 87 | 102 | 189 |
| Totals | 240 | 284 | 524 |
Grouping first and second class together Miss M. A. Lewenz found = 0·0056±0·0475 for the correlation between great ability and breadth of head; while when the second and third classes were grouped together rose to 0·1689±0·0478, the probable error of the difference being thus sensibly less than the difference. Now if such a small number as 524 can be trusted there would thus seem to be an increasing correlation between ability and size of head, when we isolate the exceptional men who take first-class honours.[1] But when we note the size of the probable error of these results, and see how comparatively small they are, it seems possible to attribute their divergence from the previous values to other sources than the relation of genius to size of head. Notably we must bear in mind that head length and breadth increase throughout life;[2] and that the honours men as a whole are older than the poll men and older in the first than in the second class—a considerable number of resident dons being included in this series of measurements—men of high honours and considerable age. Hence I think we can lay only slight stress on the apparent increase of correlation as we isolate the more brilliant men. We must finally conclude that: Very brilliant men may possibly have a very slightly larger head than their fellows, but taking the general population there is really a very insignificant association between size of head and ability. For practical purposes it seems impossible, either in the case of exceptionally able men or in the bulk of the population, to pass any judgment from size of head to ability or vice versá.
- ↑ The alteration of correlation with the alteration of the class divisions shows that the frequency surface is not accurately normal. In the general Cambridge undergraduate population, as well as in the criminal classes, the head measurements give normal curves within the limits of random sampling. See Macdonell, loc. cit., p. 181, et seq.
- ↑ W. Pfitzner, 'Zeitschrift für Morphologie u. Anthropologie,' vol. 1, p. 365.
