84 Dr Stone on the Frontal Sinus. 



verse, and vertical dimensions, and, at the same time, the face 

 "increases nearly an inch in length, and a full inch in breadth. 

 The growth of the head is more rapid during this than during 

 any subsequent period of life. Immediately after this, between 

 four and seven years of age, a remarkable difference in the mode 

 of development is observed, for the head does not continue to 

 maintain a similar ratio of growth in all its different directions ; 

 but, instead of this, the transverse gains on the longitudinal di- 

 mension, and there is scarcely any increase in its growth behind 

 the meatus ex tern us. 



This accords well with the observations of Sir William Ha- 

 milton, who, by weighing the cerebellum and measuring the size 

 of the cerebellar cavities, ascertained that the cerebellum attains 

 its maximum relative size at three years of age. By taking a 

 profile view of the posterior region of the head of a child, and 

 comparing it with a profile view of the head of an adult, the 

 eye will soon familiarise itself with this fact. 



From the age of four to that of seven years, it has just been said 

 that the transverse gains on the longitudinal dimension ; and it 

 is worthy of remark, that immediately after this period, i. e. from 

 seven to fourteen, the head increases so much in length, that the 

 longitudinal now gains sensibly on the transverse dimension. 

 This increase of development takes place, it is to be remem- 

 bered, anterior to the external meatus, and is nothing more than 

 the progress which the external table of the frontal bone makes 

 in accompanying the growth of the facial bones to which it is 

 attached, and which, at the same time, extend their distance 

 considerably from the meatus. The frontal bone, however, du- 

 ring this period, increases little or nothing in breadth, the growth 

 being principally from the meatus forwards ; hence it becomes 

 obvious, that, instead of maintaining a similar ratio of growth in 

 all its directions, one dimension of the head exceeds in the ra- 

 pidity of its growth another dimension, and one region of the 

 head increases in size, while another remains stationary. 



Having thus stated the general results of these investigations 

 concerning the growth of the head, let us consider the applica- 

 tion of these facts, and the mode in which, consistently with 

 them, the frontal sinuses become developed. Before the head 

 increases so much in its longitudinal dimension, that is, before 



