332 Sir William Hamilton’s Remarks on 
tion, renders it, however extensive, of no cogency in the 
question. 
“ Dr Morton’s method of measuring the capacity of the era- 
nium, is, certainly, no ‘ invention’ of his friend Mr Philips, 
being, in either form, only a clumsy and unsatisfactory modi- 
fication of mine. Tiedemann’s millet-seed affords, likewise, 
only an inaccurate approximation to the truth; for seeds, as 
found by me, vary in weight according to the drought and 
moisture of the atmosphere, and are otherwise ill adapted to 
recover the size of the brain in the smaller animals. The 
physiologists who have latterly followed the method of fill- 
ing the cranium, to ascertain the amount of the cranial con- 
tents, have adopted, not without perversion, one-half of my 
process, and altogether omitted the other. After rejecting 
mustard-seed, which I first thought of employing, and for the 
reasons specified, I found that pure siliceous sand was the 
best mean of accomplishing the purpose, from its suitable 
ponderosity, incompressibility, and equality of weight in all 
weathers. Tiedemann (p. 21) says, that he did not employ 
sand, ‘ because, by its greater specific gravity, it might 
easily burst the cranial bones at the sutures.’ He would, 
by trial, have found that this objection is futile. The thin- 
nest skull of the youngest infant can resist the pressure of 
sand, were it many times greater than it is ; even Morton’s 
lead shot proved harmless in this respect. But, while 
nothing could answer the purpose better than sand, still this 
afforded only one, and that an inadequate, mean towards 
an end. Another was requisite. By weighing the brain of 
a young and healthy convict, who was hanged, and afterwards 
weighing the sand which his prepared cranium contained, I 
determined the proportion of the specific gravity of cerebral 
substance (which in all ages and animals is nearly equal), to 
the specifie gravity of the sand which was employed. I thus 
obtained a formula by which to recover the original weight 
of the encephalos in all the crania which were filled; and 
hereby brought brains weighed and skulls gauged into a uni- 
versal relation. On the contrary, the comparisons of Tiede- 
mann and Morton, as they stand, are limited to their own 
