( 88 ) 
the Operator mud amount to as much as anfwers 
to the Heighth of the Bridge ee. On both Ends 
of the Brais-Bottoms, the two Piece of Brafs « «, 
of the fame Height, are rivetted on. This being 
done, at lad the Covering-Plates oo is prepared 
and skrewed on the Piece of Brafs <r <[ If the 
Machine be made pretty large, the Covering-Plate 
muff be skrewed fad, not only to the Bridge ee y 
but alfb not far from the Wheel of Multiplication. 
It mud be provided not only with round Holes, 
through which are to go the Axis of each upper- 
mod Wheel a, and the hollow Axis of the Plate / ; 
but it mud alfo have a long Slit, in which the 
Operator and Determinator may be moved up and 
down, and lad of all a fmall Window over the Plate 
of Multiplication , through which the Figure or 
Number engraved on the Plate may appear didin&ly.. 
To the projecting Skrew £ of the Plate £ is fitted 
an Handle joined to an Index in the Shape of a 
Scythe. The Skrew in t heSydem A A is a common 
Skrew, confequently the Roundnefs of the Scythe 
mud turn from the left to the right but in the 
Sydem BB, where it ought to be inverted, like all 
the other Parts, the Scythe mud turn from the right 
to the left, as in the Figure. The Ufe of this is 
to fhew which Way the Wheels are to be turned ; 
and the Skrews are to prevent the Machine’s being 
hurt by unskilful Hands. 
On the Side of the Determinator, viz,, on that 
Piece which cannot be prefTed down, is alfo skrew- 
ed a fmall Index, which may be directed to luch 
Numbers or Figures as is required. Thefe Figures 
are to be engraved in the Covering-Plate, according 
2 to 
