H4 - -1' N S' A 
cranium. To obtain a ftandard pofition for ail heads, I 
placed, after the manner of Camper, a prop under the 
foramen magnum of the occipital bone, of fuch a height, 
thafthe extremity of the nafal apophylis and the upper 
margin of the meatus auditotius externus were in a line- 
parallel with the plane of the horizon. I then conftruCted 
an inftrument in the form of a parallelopipedon, whofe 
fides admitted of varying the dimenfidns without deftroy- 
ihg the figure, fo as to be adapted to heads of different 
capacities. The upper plane, which I placed on the 
crown of the head, was loofe, ana by means of a level 
kept hi a horizontal pofition. By this contrivance, the 
refpefitive distances of the different planes gave the moft 
accurate refults which it was poffibie to obtain of the 
three dimenfion's of the head. On the living fubjeCt, I 
made ufe of a caliber gompafs. By tliefe means I com¬ 
pared Stalls of different forms and capacities. 
^ A perpetual'fource of error in the anatomical and 
phy/ioiogical researches of Greding, lias been to confidery 
as caufes of infanity; certain varieties of conformation of 
the cranium, which may, in foine iriftances, co-exift with 
this malady, but which are alfo difcoverable after death- 
in perfons who have never experienced it. To avoid er¬ 
roneous conciufions of that nature, I have meahired and 
examined a great number of fkulls in different nruleums. 
I have alfo taken, by means of a caliber compafs, the 
dimer.fions of the heads of different perfons of both fexes, 
who had been, or who were at the time, in a ftate of in- 
fanity. I generally obferved, that the two moll linking 
varieties, the elongated and the fpheroidal fkulls, are 
found indifferently, and bearing at leaft no evident re¬ 
lation to the extent of the intellectual faculties. But I 
have likewife obferved, that there are certain malcon- 
formatioiis of the cranium connected with a date of infi¬ 
nity, efpecially with ideotifm or idiopathic fatuity from 
the birth. Of the head of an ideot, who died at the age 
of forty-nine, the remarkable property was length. With 
that I contfalted the cranium of a perfon poffefled of a 
found underftanding, who died when he was twenty years 
of age, and whofe head was equally remarkable for its 
rotundity. 
“ The anatomical examination of the heads of two fe¬ 
male maniacs, of whom one died at the age of forty-nine, 
and the other at that of fifty-four, would appear to con¬ 
firm the opinion which I have already advanced, that in- 
t'enfe mental affections are the moft ordinary caufes of 
infinity, and that the heads of maniacs are not charac- 
teriicd by any peculiarity of conformation that are not to 
he met with in other heads taken indifcrimmateiy. Of 
tliefe heads, the form of the one is elongated, of the other 
fflorteried. The flattened forehead of the one, which ap¬ 
pears to form an inclined plane,, and the perpendicular 
elevation of the other, are varieties which are often ob- 
fervable, but which admit not of any induction, favourable 1 
cr otherwile, in regard to intellectual capacity. This 
obfervation, however, does not apply to a Ikull of which 
I obtained pofleflion at the death of a girl'of nineteen, 
who was an ideot from her birth. The length of this head 
is tiie fame as that of the two other maniacs; but its 
height is one centimetre above that of the fecond, and 
two centimetres above that of the firfl; whilft its breadth 
is Id's :—.a form which gives to this head a d^propor¬ 
tionate degree of elevation and lateral depreflion very 
common to ideotifm from the birth. I have marked 
both appearances in two young ideots who are now alive : 
and they are laid to prevail amongft the Cretins of the 
Pays de Valid. 
“ I have confide red the above cranium in another point 
of view. I hive contracted it with a well-formed fkull, 
and I have caufed a correfponciing fection to be made of 
both in the direction of the moft projecting part of the 
frontal bone and the angle of the lambdoidal'flat fire. I 
have hence obtained means of comparifon between the 
two irregular eliipfes which refult from thole feCHons. 
1 have obferved,. that in the well-formed fkull the two 
n i t r. 
demi-eflipfes are difpofedfymmetricalTy around the prin¬ 
cipal axis, fo that the conjugate diameters, drawn from 
the anterior left fide to the pofterior right fide, are evi¬ 
dently equal. On the contrary, in the ili-conftruCted 
fkull, the two demi-eilipfes are not placed in a fymmetri- 
cal order on the two fides of the principal axis; but that 
which is on the right takes a more prominent curve to 
the anterior fide, whilft on the pofterior it is flattened $ 
and that on the left fide the anterior curve is flattened, 
and the pofterior more projecting. This difference, which- 
is apparent at firft view, is flail more manifeft on meafur- 
ing the conjugate axes ; fince that which goes from right 
to left meafures twenty-two centimetres, and that which 
goes from left to right meafures only feventeen. I have 
found the fame peculiarity of ftruCture in the head of a 
child eighteen months old. The difference of the conju¬ 
gate axes even in this cafe was a centimetre and a half. 
Was this child doomed to live an ideot ? this is aqueftion 
which the immaturity of its mental faculties rendered it 
impoflible to determine. Another defeftive ftruCture of 
the head that I am deferibing, which mult not be omit¬ 
ted, was that of the thieknefs of the fkull. It was every¬ 
where double the ordinary denfity. From the extraordi¬ 
nary thieknefs of this fkull, it would be eafy to calculate 
how much the internal capacity of the cranium was di- 
minilhed, if its figure had been a regular ellipfokl; fince. 
it would only be neceffary to determine the folid dimen- 
fions of a figure formed by a revolving ellipfis whofe great 
and finall axes would be known. But the irregularity of 
form of the cranium precludes the adoption of fuch s> 
method of admenl'urement. 
“ The malconformations of the cranium of the above 
ideot; the depreffion of the fides, the want of correfpon- 
dence between the right and left fide, and its preterna¬ 
tural thieknefs ; mult evidently diminifh the capacity of 
the receptacle of the brain. But we imift beware of draw¬ 
ing inferences haftily. I (hall, therefore, confine myfelf 
to hiftorical faCts, without absolutely deciding that there 
is an immediate and neceffary connection between idiot- 
ifm and the various ItruCtures which I have deferibed. 
This young woman was in a-flate of complete fatuity from 
her infancy. She uttered, at intervals, fome inarticulate 
founds; but fhe gave no indications of intelligence nor 
of moral affections. She ate when food was prefented to 
her mouth, appeared to be infenfible of her exiftence, and 
had every appearance of an automaton.” The conclii- 
fion feems to be, that a malconformation of the cranium, 
can hardly be the caufe of accidental infanity, but certainly 
may be the caufe of incurable idiotifm from the birth. 
From fpeaking of the fliape of the fkull we naturally, 
pafs to the appearances of the brain itfelf. "Of all the or¬ 
gans of the human body, fays Dr. Black, the brain is the: 
moft tender ; we all know, by demonftration and read¬ 
ing, that about one eighth part of the blood, in its rota¬ 
tion, is circulated through the brain ; we know the ori¬ 
gin and diftribution of its fpinal elongation and forty pair 
of nerves ; its internal ftruCture to the moft minute dif- 
cernible filaments; its divisions'into cavities and promi¬ 
nences, many bf them with uncouth names, and fwelling! 
the naufeous vocabulary of anatomy. But ilill the latent 
predifpofition, or frailty in the recefles of the brain, or ra¬ 
the fentient principle, which render fome, more than 
others, liable to this mutiny of reafon, on the application 
of remote and obvious caufes, is totally unknown. Moft 
of the proximate caufes afiigned in authors for madnefs, 
are mere hypothefes, and of no practical ufe to the com¬ 
munity or to medicine. The pretended difeoveries of the 
anatomical knife, and the fpecific gravity of the brain, 
are equally conjectural; and many of tliefe pretended diP 
coveries by morbid: efifieCtions might with more probabi¬ 
lity be aferibed tortile effect than to the caufe of the dil¬ 
ea fe. That great phyfiologift of the intellectual functions, 
Mr. Locke, has here taught us to defpair, and acknowledge 
the imperfection of our lenles and faculties. Literature, 
however, ancient and modern, together with medical phy-. 
