r 779 ) 
from the Horizon with oar Eyes. In aifo we fet 
their Eyes accommodate ^hemrelves in their viewing a /ia- 
gle objed ; But however the rays feem to fall here more 
readily apon the external Fibres^ becaufe of the in^ 
fertion of tliQ Optic Nerve , and therefore they do not fo in* 
differently turn thi^r Eyes to difcrimimte the Motion of 
objeds as we do ^ oor is their [Sphere ef Vifim fd 
large. 
4. But to proceed to other objeaions s The cafe of 
Crofs'd'efd perfons by birth (that are fo from a (miil contort 
tion oiont of the MotoryMufcles of the Eye) I have con* 
fidcr'd at the end of the f or ementiond ^ EJfay^ andfliewa 
withal why a Morbid strabifmm, or more violent contor- 
tion of thofe Mufcles after great eonvulfions of the Nerz^s^ 
caufes always a double Vifion (to which the inftances out 
of Dr. WtUis$ &c. In p. lj6, of thofe Colkaions d@ 
refer ; ) which problem vf^sfo hard to confider of by P/m- 
pius^ and others before ; and indeed can fcarce be folv'd by 
Siny other Hyothefis. 
5. It has been urg'd That the of all th^ Fibres erf 
the Optic Nerves might be uniform^ notwithjianding the 
greater flexure of the Superiors becaufe thefc latter might 
be longer, and confequently might not have a greater ftre fis 
upon the thalami Optici then the lateral: As, if the arm of 
a tree grows bent^ the Fibres on the protuberant part feem 
not more (Iretcbt then on the concave fide^ but to take only 
a longer compafs. To which 1 anfwer that fenfe evinces 
tlse contrary in our cafe (as I fhew before> and if any one 
draws out the 0^^?^ TV^rz^^ flraight forward from the thala^ 
mus Opticus^ or as it lies in its Natural pofition^ he will 
plainly fee that the top^Fibrer prefs more on the fubjaceat 
medullary Protuberances then the lateral 0:9 make a deeper 
