17 
Sections of the skulls, however, show that some of the ap- 
parent defects of the Gorilla’s cranium arise, in fact, not so 
much from deficiency of brain case as from excessive deve- 
lopment of the parts of the face. The cranial cavity is not 
ill-shaped, and the forehead is not truly flattened or very re- 
treating, its really well-formed curve being simply disguised 
by the mass of bone which is built up against it (Fig. 17). 
But the roofs of the orbits rise more obliquely into the 
cranial cavity, thus diminishing the space for the lower part 
of the anterior lobes of the brain, and the absolute capacity of 
the cranium is far less than that of Man. So far as I am 
aware, no human cranium belonging to an adult man has yet 
been observed with a less cubical capacity than 62 cubic 
inches, the smallest cranium observed in any race of men by 
Morton, measuring 63 cubic inches; while, on the other 
hand, the most capacious Gorilla skull yet measured has a 
content of not more than 344 cubic inches. Let us assume, 
for simplicity’s sake, that the lowest Man’s skull has twice 
the capacity of that of the highest Gorilla. * 
*Tt has been affirmed that Hindoo crania sometimes contain as little as 
‘27 ounces of water, which would give a capacity of about 46 cubic inches. The 
minimum capacity which I have assumed above, however, is based upon the 
valuable tables published by Professor R. Wagner in his “ Vorstudien zu einer 
wissenschaftlichen Morphologie und Physiologie des menschlichen Gehirns.” 
As the result of the careful weighing of more than 900 human brains, Pro- 
fessor Wagner states that one-half weighed between 1200 and 1400 grammes, 
and that about two-ninths, consisting for the most part of male brains, exceed 
1400 grammes. The lightest brain of an adult male, with sound mental facul- 
ties, recorded by Wagner, weighed 1020 grammes. As a gramme equals 15.4 
grains, and a cubic inch of water contains 252.4 grains, this is equivalent to 
62 cubic inches of water ; so that as brain is heavier than water, we are perfectly 
safe against erring on the side of diminution in taking this as the smallest 
capacity of any adult male human brain. The only adult male brain, weighing 
as little as 970 grammes, is that of an idiot ; but the brain of an adult woman, 
against the soundness of whose faculties nothing appears, weighed as little as 
907 grammes (55.3 cubic inches of water) ; and Reid gives an adult female 
brain of still smaller capacity. The heaviest brain (1872 grammes, or about 
115 cubic inches) was, however, that of a woman ; next to it comes the brain 
of Cuvier (1861 grammes), then Byron (1807 grammes), and then an insane 
