PRESIDENT’S ADDRESS. 559 
Heap. 
In boys the head grows rapidly in height from 5 to 7% 
years, and then remains unchanged for several years. 
From 94 to 114 the height increases and again remains. 
stationary for a year; from about the 12th to the 13th 
year the increase is rapid, amounting to about 40 milli- 
metres in the twelve months. After the 13th year the 
growth is regular, but slow, until the adult size is attained. 
The development of the head in width presents somewhat 
analogous features to the development in height. There 
are periods of growth and non-growth, but these are less 
marked than in the case of the height. The transverse 
diameter grows slowly to age 84 years, the rate of increase 
being about 15 millimetres a year. From 84 years to 14 
years the growth is very slight, the difference in the 5} 
years being not more than 10 millimetres. 
From 14 years the growth is more rapid, and the trans- 
verse diameter expands fairly regularly year by year 
until the adult size is reached. 
The nasio-iniac-sagittal arc—that is, the length of the 
dome of the head—does not grow rapidly before the 12th 
year, the increase during the 64 years (54 to 12) being only 
55 millimetres. During the three years following the growth 
is more rapid, the increase being 130 millimetres. After 
age 15, there is very little further increase. 
The circumference of the head shows somewhat irregular 
growth up to age 104 years—or rather there are alternate 
periods of growth and cessation of growth up to that age. 
After 10} there is a regular increase in the dimension, the 
increase being at the rate of 46 millimetres per annum. 
The dimensions of the heads of boys exceed those of girls 
of equal ages. The difference in length (antero-posterior 
diameter) is irregular, and is greatest at the earlier ages, 
viz., about 60 millimetres; towards the period of puberty 
the difference greatly diminishes, and at 13 years does not 
exceed 20 millimetres. The transverse diameter of boys’ 
heads exceeds on an average that of girls by about 20 
millimetres, but at the younger ages the excess is as much 
as 50 millimetres. The circumference is also greater at all 
ages, but the difference is very slight during the years 114 
to 144; during these years, however, girls are both heavier 
and taller than boys. 
Face. 
The height of the face is considered to be the length 
from the nasion to the point of the chin, and the bizygo- 
matic breadth is the extreme width between the temples. 
