( 5 * ) 
Entry of the upper Part of their Canal. I hope 
now to make appear, that the beft way to avoid 
part of thefe Accidents, and keep open the new 
Canal from the Eye to the Nofe, is precifely to 
do nothing. This is what Experience has confirm’d 
mein, and what likewife Theory, well underftood, 
will give us a clear Conception of. 
’Tis a Thing not very eafy to determine, how 
the Tears, and the Liquid that is continually found 
on the Surface of the Eye, in order to preferve the 
Cleannefs and Tranfparency of the Cornea , can pafs 
through the Ptmila lacrymalia . ’Tis moreover 
obferved, that when one lies in Bed, this Liquid 
enters into thofe PunEia lacrymalia , which in that 
Pofition are higher than the Eye, as well as into the 
!P tin £la lacrymalia of the oppofite Eye. The Afcent 
of Liquors in capillary Tubes above the Level, might 
be propofed to explain this lafl: FacSt. One might 
alfo in certain Circumftances imagine the Road 
which the Tears keep, to pafs from the Eye into 
the Nole, to be a Sy$hon % the Ihort Leg of which 
is divided into two. ’Tis ftrange that thefe two 
Ideas, which (trike by their Simplicity, have not 
been offer’d by any one hitherto. It muff be al- 
low’d, however, that they are not entirely fufficient 
to account for the ‘Phenomenon under Confidera- 
tion. The following Rationale feems to me quite 
as fimple, and more accurate. 
The Air prefent at the Orifices of all theDudts, 
which have any Communication with the Trachea , 
is by its proper Weight determined to enter them, 
when the Refiftance happens to be diminilh’d. Thus 
as, during Infpiration, it pafies through the Mouth 
and 
