18 PHILOSOPHICAL TRANSACTIONS. rANNOl735. 



weeping; for by filling the wound with small pledgets, and putting a tent into 

 the hole, the orifice of the little common canal, that serves to convey the tears 

 into the lacrymal duct, sufl^ers a compressure, and is rendered hard, thick 

 and callous; by which, as its diameter is very small, it is easily stopped up. 

 The contusion made on this small orifice, and round about it, brings on a 

 suppuration ; after which the parts coalesce, and the orifice of this small canal 

 closes up. The pus or sanies, which in the course of the distemper flowed 

 back, both through the common canal, and the small canals, which are a con- 

 tinuation of the puncta lacrymalia, has sometimes occasioned excoriations; in 

 consequence of which there happens a regeneration of flesh during the dress- 

 ings, a small matter of which is sufficient to stop up such slender ducts. Indeed 

 those small canals, through which nothing passes for a month or two, that the 

 dressings last, either close by their own elasticity, or their diameters are lessened 

 by their small vessels becoming varicose. It is true, that injections are some- 

 times made through the puncta lacrymalia; but the propelling force of these 

 injections overcomes those resistances, which the cause that naturally drives the 

 tears into the puncta lacrymalia, is not in a condition to overcome. 



Thus it appears, from the detail of the accidents here enumerated, and which 

 generally happen more or less, that while the artist is endeavouring to preserve 

 a clear passage for the tears into the nose, he labours, without designing it, to 

 stop the entry of the upper part of their canal. Mr. H. hopes to make appear, 

 that the best way to avoid part of these accidents, and keep open the new canal 

 from the eye to the nose, is precisely to do nothing. This is what experience 

 has confirmed, and what theory too, well understood, will give us a clear con- 

 ception of. 



It is not very easy to determine, how the tears, and the liquid that is conti- 

 nually found on the surface of the eye, to preserve the cleanness and transpa- 

 rency of the cornea, can pass through the puncta lacrymalia. It is also ob- 

 served, that when we lie in bed, this liquid enters into those puncta lacrymalia, 

 which in that position are higher than the eye, as well as into the puncta lacry- 

 malia of the opposite eye. The ascent of liquors in capillary tubes above the 

 level, might be proposed to explain this last fact. We might also in certain 

 circumstances conceive the road which the tears keep, to pass from the eye into 

 the nose, to be a syphon, the short leg of which is divided into two. It is 

 strange that these two ideas, which strike by their simplicity, have never been 

 oflTered by any one. It must be allowed however that they are not entirely 

 sufficient to account for the phenomenon under consideration. The following 

 rationale seems quite as simple, and more accurate. 



The air present at the orifices of all the ducts, which have any communica- 



