By considering head-form and colour, then, we may help to cover a certain amount of the ground, vast as it is.

For remember that anthropology in this department draws no line between ancient and modern, or between savage and civilized, but tries to tackle every sort of man that comes within its reach.
Head-shape is really a far more complicated thing to arrive at for purposes of comparison than one might suppose.

Since no part of the skull maintains a stable position in regard to the rest, there can be no fixed standard of measurement, but at most a judgment of likeness or unlikeness founded on an averaging of the total proportions.

Thus it comes about that, in the last resort, the impression of a good expert is worth in these matters a great deal more than rows of figures.
Moreover, rows of figures in their turn take a lot of understanding.
Besides, they are not always easy to get.

This is especially the case if you are measuring a live subject.