PROFESSOR T. A. HE ARSON ON THE KINEMATICS OF MACHINES. 
39 
written thus 
A—T> 
f 
-A and the other is the common crank and 
connecting-rod engine with eccentric and slide-valve, the formula for which is 
TJ- 
i 
In Conjunction IV. it is the two opposite or alternate links of A to which the two 
additional links are coupled in the formation of mechanism B„ The two selected 
alternate links of A must each be provided with three joints. Thus, mechanism 
B, as well as B', will consist of five links. The formula may be written thus 
when one of the two three-jointed links is the frame link. 
The mechanism of the Crosby steam indicator affords an example of this conjunction. 
The same formula will represent the movement if an I be substituted for the third U 
from the left. 
The Atkinson gas engine may be quoted as another example, the formula being 
If three or more simple mechanisms are compounded, the varieties in the ways in 
which they may be conjoined are much more numerous. It is not desirable to set them 
forth here. Enough has been said to indicate the lines which it is proposed should 
be followed in systematizing them. The formulae of some well-known machines, 
consisting of three or more simple mechanisms, are added. 
Peaucellier’s straight-line mechanism is an example of a three-fold conjunction, 
and may be written thus, 
The Beam engine, with Watt’s 
shaft is an example of a four-fold 
parallel motion, and engine piston driving a rotating 
conjunction, it may be written thus, 
-u- 
fT-Tj—A i-j y 
