0'18 PHILOSOPHICAL TRANSACTIONS. • [anNO i74g. 



converted into a staff, by making a deep groove through its whole length, it will 

 better answer the end desired, than if it were possible to suffer the staff itself 

 to remain in the bladder during the operation ; for, when a large stone is laid 

 hold of, and the forceps of course much devaricated, insomuch that the extrac- 

 tion of the stone is found to be impracticable with safety, without a second inci- 

 sion on the parts on the stretch; you then slide the point of a narrow knife on 

 the groove of the forceps quite on into the bladder, and it will divide the very 

 part which needs it most ; while tlie rectum, on account of its flaccid state, will 

 most certainly escape wounding. If the wound is desired to be but little larger, 

 the forceps must be but gently drawn forward when the incision is made ; but if, 

 on the other hand, the stone prove extremely large, the forceps should be then 

 drawn forwards with a force sufficient to put the bladder on the stretch ; and by 

 this management the dilatation may be made as great or little as is required. 



As the common knife is not so proper for this purpose on account of its 

 breadth, Mr. M. got one made of a more convenient form, with a gorget-handle 

 and button point, as in the bubonocele knife. This method, as it removes all 

 occasion for violence to the bladder, will reduce the effects of the operation nearly 

 to those of a mere incision only, which might, as now, sometimes prove fistu- 

 lous, but he believed hardly ever mortal. 



He would not be understood to mean that it should be used in common cases, 

 and moderate sized stones; no, Mr. Cheselden has sufficiently demonstrated to 

 the world, by experiment, the inconvenience of cutting beyond the prostate, 

 when it can be avoided. He would only say, that where a large stone offers, 

 and the circumstances are such, that the operator is under a necessity of tearing 

 the parts to pieces, unless divided by an incision, the latter is more safe and 

 eligible. 



The principal advantages of this contrivance are, 1 . That the degree of dilata- 

 tion is in the operator's power, to the greatest exactness. 2. That it will infal- 

 libly divide those parts only which are on the stretch; and for this reason, 3^ 

 The rectum, if it is empty, and consequently flaccid, must certainly escape 

 wounding. Its great simplicity is another circumstance much in its favour; for 

 it seems allowed on all hands, that the less an operation is incumbered with in- 

 struments, the better. In common cases, where the assistance of this method 

 is not wanted, the forceps is not the least incommoded as to its general use , but 

 if the stone prove large, which can never be certainly known till it is laid hold, 

 of, the remedy is at hand. 



These forceps and knife are represented in fig. 1, 2, 3, pi. ]i. Fig. ], the 

 forceps, with the knife, ab, applied to one of its cheeks; c, the button; bfg, the 

 handle. Fig. 2, the cheek of the forceps, with the groove in it de. Fig. 3, the 

 knife; the blade ab; the button c, made to fit, and slide along the groove de; 



