VOL. LXX.] PHILOSOPHICAL TKANSA-CTIONS. 67Q 



resolution of the equations a^ -\- qx = r and ,r^ — qx = r; can be obtained by 

 means of that substitution. 



^rt. 17. These are the methods of investigation by which I conceive it to be 

 probable, that Cardan's rules for the resolution of the cubic equations x + qv 

 = r and x^ — qx = r, together with the limitation of the rule relating to the 

 latter of those equations, and their inapplicability to the 3d equation qx — x^ 

 = r, may have been discovered by the first inventor of them. 



XIII. A New Method of treating the Fistula Lachrymalis. By. Mr. IVm. 

 Blizard, Surgeon, F. A. S. p. 239. 



After premising some remarks on the causes of obstruction in the nasal duct, 

 Mr. B. proceeds to state that from whatever cause the obstruction had its origin, 

 in its early state, when unattended with a morbid change of the contiguous parts, 

 it is considered as the first and most simple stage of the fistula lachrymalis. It 

 is in this stage that the means of obviating the necessity of a troublesome and 

 uncertain operation should be employed, with any rational expectation of success. 

 The principal of these means are : 1 . Compression ; declared by experienced 

 practitioners to be injudicious. 2. The passing an instrument into the nostril, 

 and up the duct ; an operation very painful to the patient, and exceedingly trou- 

 blesome to the operator. 3. The introducing a probe through one of the 

 puncta into the duct, after M. Anel's manner ; by experience proved to be inade- 

 quate to the design. 4. The impelling a fluid, by a syringe, through one of 

 the puncta, as directed by M. Anel ; allowed by judicious and experienced sur- 

 geons to be sometimes useful. 



Reflecting on the last method, Mr. B. was induced to think, that if a fluid, 

 of a great degree of specific gravity, as quicksilver, could be passed through one 

 of the puncta, so as to fill the sac and duct, and press on the obstructed part, it 

 might be reasonably expected to remove the obstruction in the first and simple 

 stage of the disease ; at least, to have a much better chance of producing this 

 effect, than a watery fluid, urged through the punctum in an unfavourable di- 

 rection ; besides, it would be no bar to the use of proper general means. 



Flattered with the seeming reasonableness of the suggestion, and convinced of 

 the safety of the experiment, he resolved on making a trial the first opportunity ; 

 which soon occurred to him. Mr. M — B — , a sadler, in Mark lane, had 

 been troubled with a flux of tears and mucus down the cheek from the puncta of 

 the right eye-lids, about 7 months. There was a degree of swelling or disten- 

 sion of the sac, attended with pain. On pressing the sac, much ropy fluid, of 

 a whitish colour, was forced through the puncta. The discharge was always in 

 greatest abundance in the evening ; at which time he had a dimness of sight in 

 that eye. The usual means had been employed, without success, by his sur- 



