152 
[LLL LILILIZIE > 
4, 
Fig. 48. Spark chronograph; A, electric motor; B, flanged chronograph drum; a st-ip of paper is Atted 
round the drum and the ends are passed through a slot C and clamped by a sliding spring chp D ; 
the most suitable paper is the black-surfaced kind used for linings books; E, four spark-points, 
1/32 inch clear of drum; F, iron crown wheel with 10 teeth; G. magnet and coil. 
