PLATE 15 
One cage of recording apparatus showing connections with the signal 
magnets, the pointers of which mark the excursions of the floors on the 
smoked paper of the drum of the chronograph. Three such cages are 
arranged to make their records on one chronograph. 
ABBREVIATIONS 
blk. 
adjustable block. 
b. p.—hbinding post through which the levers are connected to one pole 
of battery. 
c. wr.—wire connecting the supporting frame of signal magnets to other 
pole of battery. 
lr. sup.—metal support for fulerum of lever. 
lt. br—tlight bar which in connection with the frame (tr.) attached to 
the floor prevents the latter from tipping. 
tr.—truss-like frame attached to floor. 
wt.—counterweight. 
Contact between the platinum points (pl. pt., and pl. pt.., figs. A and 
B) completes the cireuit, a part of which is formed by one of the coiled 
wires seen in plate 15. Each lever has its platinum contacts and is con- 
nected with one of the signal magnets by one of the coiled wires. (See 
description, pp. 109-110.) 
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