On the Animal Calculus, 251 
1 : the great Torment of the Patients, and which 
! they cannot fbmetimes be delivered from with- 
in out cutting them out, might be drawn out by 
the following Inftrument, viz. 
31. I cut off the lower end of a ftrait Cch 
theter which made it a proper Canula for a 
Stillet or Forceps to pafs thro'; the lower end 
of the Forceps was divided into two Springs, 
like Tweezers, whofe Ends were turned a little 
inwards ; thefe Springs wejre made of fuch ^ 
Degree of Tendernefs, and Pliancy, as not to 
bear too hard againft the Sides of the Urethra^ 
by their Dilatation. 
32. When this Inftmment is ufed, the 
Springs are drawn up within the Canula % 
which being paffed into the Urethra^ as far as to 
the Stone, the Canula mull; then be drawn 
back, fo far as to give room for the Forceps to 
dilate j which dilated Forceps being then thruft 
down a little further, fo as to embrace the 
Stone, then the Canula muft again be Aid 
down, to make the Forceps take fall hold of 
the Stone, fo as to draw it out. 
33. I feat this Inftrument to Mr. Ranby^ 
to have his Opinion of it, who tells me that 
upon repeated Tryals he found it extrafts thefe 
Stones with great Eafe and Readinefs : And 
that 
