DIFFERENT RACES OF MANKIND. 349 



weight of the brain estimated from the cubic capacity of the skull, allowance of seven- 

 teen jDer cent, being made for membranes and fluids. The following column shows 

 how much this estimated weight differs from the real weight of the brain, either ex- 

 ceeding it, -1-, or falling short of it, — . And the last column points out which per- 

 centage deduction would bring the estimated weight nearest to the real weight in 

 the large series of examples examined by Dr. Weisbach. These last percentages are 

 very instructive. They vary from fourteen per cent, to twenty-three per cent., and 

 show that although sixteen per cent, is the proper deduction in the vigor of life in 

 men, — that is, from twenty to thirty years of age, — and even fourteen per cent, in 

 women, in both of whom the serosity of the brain is small in quantity ; yet that 

 seventeen per cent, is the nearest general average, as it prevails in the one hundred 

 males of all ages from ten to ninety years, as Avell as in the entire series of one hun- 

 dred and fifteen cases of males and females. Indeed, it appears to approach remarka- 

 bly close to actual observation. Whilst in the five growing males below twenty 

 years of age, and in the nine males between thirty and sixty years of age, when the 

 brain has reached the period of incipient decline ; in both these cases the fluids of 

 the brain are a little more abundant, and require an allowance of eighteen per cent, 

 for them and the membranes. But the most striking fact brought to light in this 

 table is that after sixty years of age the fluids of the brain in men go on increasing- 

 rapidly to extreme old age, demanding a deduction of no less than twenty-three per 

 cent. 



It should here be mentioned that the internal capacity of the skulls embraced in 

 the following tables has been obtained not exactly in the mode pursued by Morton, 

 by filling them with white mustard seed, or with shot, but, as uniformly as possible, 

 with dry Calais sand of a known specific weight of 1425, water being 1000. The 

 brain-weights have been obtained by the conversion of the ounces of sand into ounces 

 of cerebral substance, of the specific gravity of 1040.* 



Whilst writing these lines, I learn that a very accurate observer and able anatomist 

 has carefully tested the properties of different substances in their application to this 

 purpose of gauging the capacity of skulls, and finds them to vary materially .f He 

 has accomplished this by filling the same shidl " with a given material, which was 

 well shaken down, and compressed until no more could be received," eight separate 

 times, so as to compare the result of each experiment ; the whole made clear by a 

 table. The contents were then poured into a measure, and the measurements noted 

 in cubic centimetres, each time. Seven different matters were employed, namely 

 peas, shot, beans, rice, flaxseed, coarse sand, and fine sand. The purpose was to try 

 the uniformity of result by these difierent media, and the conclusions came out nearly 



* See Crania Britannica, p. 222. 



t Observations on Crania. By Jeffries Wyman, M.D. Boston, 1868. 



