DIAGONAL, 
of any one dire& force into any two oblique “forces ; which 
as a Ue Rane are abundantly confirm rom 
han this principle, that eminent aiegice 
eer re de clipes! orbits defcribed by the planets 
round the fun, and the s fince been m iy in 
veltigated io carried ak ee by Monf. ie Place. 
Toa the priaciple to the contruction of any ma- 
chine oer requires the line of motion to be frequently, or 
inceffantly changed, it is only irae ae to ufe either two or 
three moving powers acting at the fame time upon the body 
to be moved in different planes. For the fake of conveni- 
will, in general, be found mott sean ae that 
Con- 
a {quare or parallelo ogram; and if 
three are neceffary, ce will be in the direction of three 
fides of a cube, each fide being at right angles to either of 
the others. The firit of thefe is reprelented by fig. 12 Plate V. 
Mifcellany. Tf two forces be app! lied at the fame time to move 
a body at B, and a& upon it in the directions of the lines BC, 
BA, and if thefe — os produce equal velocity, the 
will be defcribed 
forming an aly of 36° 34' with BC, and one of 63° 2 
with B A nearly, the latter being the complement of the 
face From this it will be evident, that by varying the 
velocity given by the moving powers, every angle contained 
in the quadrant of a circle will be produced as may be 
e 
e t be 
fuppofed, that one of the two forces, moving at right angles 
to each other, is in a horizontal, and the other in a vertical 
direction. The fir of thefe motions will be produced by 
the rotatory motion of the wheel, A, (jig. 13-) upon its axis 
B, and the hor’ ‘zontal motion mill be communicated to the 
upon its axis, B 
, by means of the lever, 
fulerum G, or any other fimilar mechanical contrivance. 
um 
If the wheels are placed upon the fame axis, the combined: 
application of their powers will be feen by infpeGting Ag. 15. 
fs. 14, the lever, F, is placed below the vertical wheel, in 
upon te means of a cord, wire, 
e operation of thefe wheels, to produce either uniform, 
or diverfified motion, depends entirely upon the fhapes into 
ledge of the mann forming this operation, is the 
moft important da of the bufinefs of the engineer, or me- 
chanic, who plansthem. Recurring to fg. 12, let it be fup- 
that in one — of the axis whch carries the 
ed upon is required to move from 
B to E, and ce to return to B, deferibing in both cafes 
ee diagonal line BE. In this cafe the whole line of mo. 
rming an angle of 45° with i. of each of the 
their momenta mul val. Ifthe mo- 
or oug! ht to be, communi eared at intervals, the 
wheels fnould be s coutruGed as a feries of concentric circles. 
It is 
preceding. rom 7 to £2 the radii again increafe a pro- 
duce the returning motion u t C be 
fquare frame of an oe or fuf- 
pended, as to move freely, either i zontal or vertical 
direction, and let a piece of paper or cisth te ttretched upon 
ite Let there be alfo a fixed inftrument placed at right an= 
gles to the plane of the frame (as a pencil), the point being 
in contact with the paper or cloth. Then, if the wheel, A, 
gives the vertical motion to the fame body would, 
volution in the fame way, bring the point from I - M, 
‘fg. 14.), and again return it to I. Such would be the effect 
of each of the wheels ating feparately ; but if their aGion 
is combined, the fee Ay line, I K, will be produced by 
the preflure of the point, and the motion of the frame C. 
It w an evident, that were the frame, C, Rationary, and 
th nt move 
the fame dire&ion by the aétion of the 
two hen the fame effe& would 
Mere motion m might b 
aed which m 
as it does not at all affect the general principle, muft be left 
to the difcretion of the engineer, and re egu ulated 
particular « circum ances ma 
is 45°, and the 
body C, at the aia when the frition-wheel, H, comes 
in contaét with each divifion. But if inceflant motion be 
required, the deviation mult be oe ne then the wheel - 
will — like inclined planes applied to a circle. 
inery to which thefe ae were ape 
Sie a great diverfity of figures was required, and thefe 
x 
hand: of an n engine was contrive 
fome refpects, to that a Mr. Ramfden, for div viding aes 
matical inftruments, and which fhall afterwards be defcribed,, 
If, inftead of the line BE, it is required to defcribe i 
line BD, it will be neceflary that the defcents -and afce 
which produce the vertical motion, fhould be lefs than thot. 
which give the horizontal ; and by the common principles . 
of right-angled trigonometry, thefe will be to each other in 
