( ) 
will (land before the ioth Tooth in the Bottom, and 
the Operator is pulled down fo far. If you have a 
mind to apply thefe Rachet-Teeth on the Outfide of 
the Plate o 0, that covers the Whole, you may fit 
the Lock to it accordingly : But in this Cafe the 
Covering* Plate mud be well fattened. 
For Multiplication and TDivifion, there is pro- 
perly in each Syftem but one Wheel, like wife di- 
vided into 10 Rachet-Teeth, on which is rivetted 
the round Plate /, on which are engraved the Num- 
bers or Figures : Thefe Wheels have no occafion 
for any Bridge, but may turn about a ftrong Pin of 
Steel, lolder’d to the Bottom. TheRachet-Wheel^^ 
refts on one Side upon the Determinator, and upon 
a Piece of Brafs of the fame Thicknefs, to which 
are fattened the Stop n> and the Spring /. Upon 
the Operator is another Stop 0, with its Spring ; 
which Stop has a fmall Arm at 0, which is checked 
by a fmall Studd, to hinder the Spring’s prefling 
the Stop lower down than it ought : By which 
Contrivance it is fo order’d, that after the Operator 
is Aid down fo far as it can go, in being Aid up 
again, the Stop 0 will turn but one Tooth of the 
Wheel m rn . The round Plate l has in its Middle a 
fmall hollow Axis, on which are turned firft two 
Shoulders, and then a Skrew : This Skrew in the 
Syftem A A is an ordinary one, winding from the 
left to the right. 
But as each Syftem ought to have Communication 
with the preceding one, though not with that which 
follows ; to this end a projecting Tooth of Commu- 
nication made of Steel $ is rivetted to the upper 
Plane of the uppermoft Wheel a. This Tooth 
2 mutt 
