43 



APHORISMS ON THE FRONTAL SINUSES, 



AND THE EXTENT OP 

 THEIR INTERFERENCE WITH PHRENOLOGICAL OBSERVATION. 



Numerous and diversified inductions confirm the following 

 Aphorisms. This being certain, their general accuracy is asserted ; 

 and no one has a right to impugn these statements, who has not 

 devoted much time, labour, and expense, to a repetition of the in- 

 quiry on which they are founded. 



I. Like all bones of the same kind, that portion of the skull which 

 includes the Frontal Sinuses varies in thickness. Such variation* 

 however, is neither so great nor so manifold as to prevent our dis- 

 tinguishing the general law of its development. 



II. When its organization has not been disturbed, the Frontal 

 bone, immediately above the nose, is nearly two lines in thickness, 

 by the tenth year of life ; by the^fteenth, it is tpjo lines and a half; 

 by the twentieth, it is three lines almost ; by the fortieth, it is about 

 three lines and a half; and by the fiftieth, it varies between three 

 and a half oxidi four lines. And whether the bone retains its origi- 

 nal cellular structure, or has become hollow, this is the natural pro- 

 cess, and these are the ordinary degrees of its thickening, between 

 childhood and the adult age. 



III. Till late in life, the bone's hollowness does not enlarge the 

 distance of its external surface from that of the healthy brain. — 

 Sometimes, after the tenth year, the space between the cranial plates 

 is greater when no cavity exists ; at other times it is less, when a 

 cavity has supervened. Sometimes, a bony crest appears on the 

 superciliary arch : this crest occasionally contains cellular texture . 

 but most commonly it is hollow. It can be distinguished by expe- 

 rienced observers ; and, exclusively of this, the bone, whether hol- 

 low or solid, preserves the usual thickness. 



IV. During the foetal and infantile states, the Frontal Cavities 

 do not exist. After the seventh year, they begin to be perceptible, 

 and continue to enlarge gradually till the latest stage of life. The 



