[ 5 6 7 3 
T. S. I thought it would not be improper, if I 
fhould attempt to demonftrate to what great Exad- 
nefs Machines of this Nature may be made to 
operate. 
A Specimen of which I beg Leave to prefent as 
follows : Admit the Barrel 4 Inches Diameter, the 
Roch- wheel to be cut with 48 Teeth, the great 
Wheel to have 32, anfwerable to a Pinion with 8. 
The Reafon of pitching on a Barrel of this Dimen- 
fton is, that it may be more precifely judged what 
Extenlion has been made ; for repeated Revolutions 
of the Girt upon the Cylinder, in extending, would, 
by its uncertain Increafe, fubjed the Judgment to err j 
whereas the utmoft Extenfion required comes within 
one Revolution of this Barrel. The Teeth of the 
Roch to be numbered at every Fourth, which will 
be at every Inch, and equals in one Revolution the 
Periphery of the Barrel ; confequcntly every Tooth 
of this Roch will ftretch the Limb One- fourth of an 
Inch : So though the Spring or Catch to the faid Roch 
fhould pafs the capital Numbers, and Bop in the 
Interfpaces thereof, it is only counting from the laft 
capital Number to the Place where the Spring is, and 
that gives the Parts of the Inch : By the fame Rule 
the Winch, every Turn it makes, will gain a Fourth 
of this Wheel, which will be 3 Inches, or 12 Teeth j 
and 4 Revolutions thereof will anfwer to the Peri- 
phery of the Barrel : So by mea Turing the found 
Limb, and comparing the fra&ured therewith, the 
Extenfion required may be nearly demonftrated. 
With the Ufe of this Machine, I fhould recommend 
the 18 Tail Bandage to the circular Rollers o>{ Hip- 
pocrates, fince they are both lefs troublefome to 
the 
