J. M. Stilman—Bernardinite. 93 
duces apparent torsion, because the spatial meridians are there 
convergent. ut in convergent motion, on the contrary, there 
is a real rotation on the polar or optic axis. This is shown by 
the fact proven in my previous paper* that one eye, without 
changing its position, will rotate through the influence of the 
convergent motion of the other eye. 
exactness. In convergent motion, on the contrary, though the 
eyes may each move through an angle of 45° or more, the posi- 
tion of the spectral image is the same, viz: in front; and 
- though the eyes in extreme convergence may rotate in opposite 
directions each 10°, yet the spectral image retains its vertical 
position. The reason of this is that, although there are two 
retinal brandings, and therefore two spectral images, the exter- 
nal representatives of these brandings, yet the brandings being 
on corresponding points of the two retine, their external rep- 
resentatives, the two spectral images, are indissolubly united. 
Their separation, either wholly or partially, would be a viola- 
tion of the law of corresponding points, a law which is never 
violated under any circumstances whatever. 
n conclusion, then, it is evident that when the eyes move in 
the same direction, parallel to each other, as in ordinary vision 
of objects, all their motions are governed by the Law of Listing. 
But when, on the contrary, they move in opposite directions, as 
in strong convergence, then the law of Listing is entirely abro- 
gated or overborne, and another law reigns in its place. 
Art. XI.—Bernardinite: lis Nature and Origin; by J. M. 
STILLMAN. 
In a previous number of this Journal+ I published the re- 
sults of a chemical investigation of a resinous substance from 
San Bernardino, sent to me by Hon. B. B. Redding, which was 
said to occur in the form of vein in detached masses, and the 
vein to be traceable for three miles. The finders (farmers or 
“ranchers” of that vicinity) sent at the same time pieces of 
rock as vein-stuff which contained this peculiar resinous sub- 
stance in the crevices. Some months later another specimen 
was sent to this University from Santa Afia in the same section 
* This Journal, II, vol. xlvii, p. 162. + IL, vol. xviii, p. 57. - 
