REVERSE AND CONVERSE CRANK& 2^1

hyperbolae ( 47), the form of which necessarily makes it some- what difficult to realise the motions they represent.

FIG. 209.

The contracted formulae for these mechanisms must, in the first place, make their characteristic property of anti-parallelism clear, we therefore put its symbol between those of the cylinder

\ \

FIG. 210.

fl

pairs. The chain, unfixed, will then be written (C" 2 ' Z 6" 2 '). The reverse anti-parallel cranks will be (C'^C'^f or (C" 2 'zC' 2 ') b , of which formulae we need use only one, let it be the former,

u 2