DIAGONAL. 
the former principle. , 
Applicatien of Three Forces. . 
As already ‘fhewn, the application of. two forces, if uni- 
‘form, will produce the diagonal o f 
ram. Ift ied i 
motion abfolutely unlimited, and is merely am extenfion of 
iple - 2 
Three wheels, which produce motion in 
‘ftraight ‘lines, muft therefore effect every poffible direGion 
ion, and the third wheel is to be cut precifely upon 
‘the fame principles as the former two. 
iti ing -automata -are entirely ma- 
by the agency of three wheels, 
“pen, or pencil, with w sich he. writes, {crewed or fitted into 
hand. -’ Before him‘let ‘there be a cubical box, repre- 
fenting the table upon which he writes, and fitted:to:contain 
7 By i right arm is to be -moved. 
head, and left arm, may alfo be confidered 
-as holléw framing,-within which the motion may. be commu- 
M 11)2¢6 bt he 1 
blank or {pace'is to be left, or when the hand of the au- 
‘tomaton is to be fhifted from one place to another he 
dite@tion of the fir force may be fuppofed to be fuch a 
fi 8 
swould produce a motion from the top to the bottom of the 
rt ¢ er 
* 
hen" app 
“ought to. 
The automaton will be the 
h_ which are diftinguifhed by the letters, H, I,:and 
set 
stablet on epaper,. as thefe words are penerally underftood 
Ww pplied. to. writings or baoks. 7 econd motion 
give a-direGion from left to right, which will be, 
of courfe, at right angles to the former, and ‘both may ie 
‘reverfed.at:pleafure by the fhape:of the wheels.. The third 
‘motion will life the hand and pencil from the tablet, to pros 
duce the bold and faint: lines, and to difengage it che ck 
¢ + 
o 
ia 
ary, 
Figs. 25 and.26. Plate VII. are reprefentations of fuch a 
oe Fig. 25;i levation of the aut Be ee erica 
and the moving and moved parts are as follow. Th nas 
reprefented by the ae diltinguifhed by the fester 
A. The farft motion from the top to the bottom o 
is effeCted by the wheel, B, ee ames upon the ae - sa 
‘wheel gives motion to the lever, E, refting againft the wheel 
upon a level with the centre, and neareft to the {peétator’s 
eye. When the axis revolves upon its centre, the wheel bs 
communicating motion to the lever FE, which is eeniedes 
by a joint with the {mall horizontal axis fitted in the frame 
H, continues the motion to the lever F, reprefenting the 
bone of a humanarm from the fhoulder ito the elbow. g is 
bottom, is produced. The fecond motion, from left to ri 
to right 
is done by the wheel, C, upon the fame axis. By the ei. 
tion of the axis, this wheel ats upon the lever, I, which moves 
the frame, H, an e lever, F, in the dire@tion required; 
compais of the’ automaton. . When a great number of 
movements is required, it is plain that many more wheels 
ma beadded, and for this there is {ufficient room within the 
boxes which reprefent the table. and-the feat. ‘Fhe joints 
K, are only 
fingle, to allow a motion from left'to right, and vice ver/i3 
the lever ies the Ellie to the back of the machine, but to 
prevent the lever from diverging. from the wheel. is i 
hewn at P, in both figures. : . . Se 
From the defcriptions given, it is prefumed that readers 
conyerfant with the ftudy of the theory and praGtice of a 
- chanics, 
