IN THE DIFFERENT EACES OE MAN. 
515 
Wilaiam Hamilton, Dr. Sims, and Dr. Clendinning. Sir W. Hamilton estimated the 
weight of the adult male encephalon at 3 lb. 8 oz. troy, and the female at 3 lb. 4 oz., 
which are nearly 48 oz. 5 dr. and 43 oz. 15 dr. avoirdupois. On calculating the 
weights of the brain in the two sexes separately, from the observations published by 
Dr. Sims, I find the male brain, in 54 persons between 20 and 60 years of age, to average 
47 oz. 13 dr. ; and the female brain, in 58 persons, 44 oz. and 10 dr. Dr. Clendinning 
states the male brain, in persons between 21 and 60 years of age, to average 45*85 oz., 
and the female 41*25 oz. These several averages, together with those deduced by Dr. 
Reid and myself, range between 45f oz. and 50 \ oz. for the male, and 41|- oz. and nearly 
45 oz. for the female”*. 
Dr. Robert Boyd states, as the result of his great and continued metrological labours 
upon the weight of the brain, that the average weight of the encephalon in insane males 
at adult age, varied from 48*17 oz. to 43*87 oz., and in insane females from 44*55 oz. to 
40*55 oz . ; and that in the sane at the same period of life, the average varied in the male 
from 48*2 oz. to 45*34 oz., and in the sane female from 43*7 oz. to 39*77 oz. To place 
this in another form, it may be said that the average weight of the brain in 
insane English men was found to be 46*02 oz., or 1304 grms. ; and in insane English 
women 42*55 oz., or 1206 grms. In the sane English brains the average for the men 
was 46*77 oz., or 1325 grms.; and for the women 41*73 oz., or 1183 grms., or, taking 
both together, the mean would have been 44*25 oz., or 1262 grms.f. It will be seen 
that this result does not quite agree with the weight as deduced from the capacity of 
our English skulls, nor with Dr. Peacock’s observations with the scales. It is rather 
more than two ounces less than our mean, and three ounces less than Dr. Peacock’s. 
The conclusions given by Dr. Thurnam from the examination, by actual weighing, of 
the brains of 257 insane men and 213 insane women, who died in the Wiltshire County 
Asylum, agree very closely with those of Dr. Boyd. The average weight of the former 
was 46*2 oz., or 1309 grms. ; that of the latter 41 oz., or 1162 grms., producing a mean 
of the men and women of 43*6 oz., or 1236 grms., a little less than the mean derived 
from Dr. Boyd’s results. 
6. Irish . — The Irish brains of these 28 skulls have been slightly larger than those of 
the English. Still the mean of the series is less, viz. English, 47*50 oz., or 1346 grms. ; 
Irish, 46*70 oz., or 1323 grms. 
8. French . — Of these there are 16 examples, 9 of men and 7 of women, or nearly an 
equality of the sexes. The mean of the series is 45*17 oz., or 1280 grms. They are 
decidedly below the English. 
Dr. Parchappe weighed a few French brains, and the result, as stated by Dr. Thurnam $, 
* Op. cit. p. 19. 
f “ Tables of tbe Weights of the Human Body and Internal Organs in the Sane and Insane of both sexes at 
various ages, arranged from 2614 post-mortem examinations. By Robert Boyd, M.D.,” Philosophical Transac- 
tions, 1861, p. 261. 
+ Loc. cit. p. 15. 
