TOL. XLVIII.] fKILOSOPHICAL TRANSACTIONS. 357 



the shadow passed over Kerkisia, not improbably, the Carchemish of the prophet 

 Jeremiah, and a little to the north of Bagdad. It is not improbable therefore 

 that it crossed the Tigris not far from the place where, it seems by Xenophon's 

 account, Larissa was situated, and where consequently it would cause such a 

 darkness as might well be attended with the eftects he mentions. 



This eclipse is, Mr. C. thinks, no inconsiderable acquisition to history and 

 chronology, and is at the same time a confirmation of the suspicion, that in 

 these very anc;;ent ones, there is some allowance or other to be made for the in- 

 fluence of some cause, whatever it may be, hitherto not fully determined. This 

 must be left for future observations. In the mean time however it may be of 

 service to the science of astronomy to examine all the past eclipses that can be 

 come at, and compare them with circumstances in the best manner we are able. 



XXIV. A new Method of opening the Cornea, in order to Extract the Crystalline 



Humour. By Mr. Samuel Sharp,* F. R. S. Surgeon to Guy's Hospital, p. l6l. 



The operation of discharging the crystalline humour from the eye, for the 

 cure of that species of blindness called a cataract, was a k'w years since invented 

 by Mons. Daviel, who performed it on many jjatients with remarkable success. 

 Supposing it therefore admitted, that the extraction of the crystalline humour 

 has been found by experience to be a useful method of cure, Mr. S. here sub- 

 mits to the Society a new manner of making the incision of the cornea, by which 

 Mons. Daviel's operation may be very much shortened, the patient would suffer 

 less pain, and every skilful operator be equal to the undertaking. 



Place the patient in the same situation as for couching, either opening the 

 eyelids with your fore finger and thumb, or letting an assistant raise the upper 

 eyelid, while you yourself keep down the under eyelid. Then, with a small 

 knife, holding its edge downwards, make a puncture through the cornea near its 

 circumference, into the anterior chamber of the eye, in such a direction, as to 

 carry it horizontally, and opposite to the transverse diameter of the pupil ; after 

 which you are to pass it towards the nose, through the cornea from within out- 

 wards, as near to its circumference as in the first puncture. When you have 

 made the second puncture, push the extremity of the blade one-seventh of an 

 inch beyond the surface of the cornea, and immediately cut the cornea down- 

 wards, drawing the knife towards you as you make the incision. After this, you 

 press gently with your thumb against the inferior part of the globe of the eye, 

 in order to expel the cataract, and the operation finishes, according to the dif- 

 ferent circumstances, as in the manner proposed by Mons. Daviel. 



One extraordinary benefit seems to arise from the use of this single instrument, 



• Author of 2 publications much esteemed, viz. one On the Operations of Surgery 1743, aud 

 another entitled Critical Inquiry into the present Slate of Surgery, 1750. . 



