362 Mr. T. Gray on an Improved 



the clockwork to run on without the governor which regulates 

 the slow speed. The rate of motion then rapidly increases 

 until the second governor acquires sufficient velocity to con- 

 trol the speed, after which the paper moves forward at a rapid 

 but uniform rate. In order to again reduce the speed after a 

 sufficient interval has elapsed, the rolling forward of the hall 

 / allows the unbalanced weight of e to bring a wheel I, on the 

 spindle of which a " snail/' m, is fixed, into gear with the 

 pinion, w, which forms part of the clockwork mechanism. 

 The spindle of I rests on a spring, o, which is adjusted so as 

 to push the lower part of the " snail " just into contact with a 

 pin, p, fixed in the lever b. The weight of e acting through 

 the pin p on the " snail " deflects the spring o and brings the 

 wheel I into gear with the pinion n. The " snail " is then gra- 

 dually moved round and raises the ball e and the end of the 

 lever b, at the same time lowering the rocking platform g. 

 After this has proceeded so far as to cause the platform g to 

 come below the lever of h the ball rolls back to its original 

 position; and, as the " snail " moves round, the platforms 

 are gradually raised to their original positions, the wheel j 

 again comes into gear with the pinion k, and the speed is re- 

 duced. The wheel I remains in gear with the pinion n for a 

 short time after the speed is reduced, so as to allow the final 

 adjustment in position of the platform g and the ball / to be 

 made gently. After this is accomplished a hollow in m allows 

 the spring o to push the wheel I out of gear, and everything 

 is left in readiness for the next disturbance. 



In order to obtain the rate at which the paper is moving at 

 any instant during the transition period between the slow and 

 the quick speed, the lever a is made to close an electric circuit 

 at q, which causes an electromagnetic vibrator, indicated at J 

 (fig. 3), to come into action and write equal short intervals of 

 time on the record-sheet. The short intervals are sometimes 

 given by a vibrating reed, which is the most convenient 

 arrangement if the intervals are to be fractions of a second ; 

 but, for marking seconds, a break-circuit arrangement worked 

 by the clock, k, is preferable. The way in which the siphon, 

 D, is made to record both the long and the short time-intervals 

 is sufficiently explained by the diagram, fig. 3. 



One of the " conical pendulums " used for actuating the 

 siphons which record the two horizontal components of the 

 motion is illustrated in plan in fig. 4, and in elevation in 

 fig. 5. It consists of a thin brass cylinder r, filled with lead, 

 and held deflected by a light tubular strut, s, furnished with 

 a knife-edge at t, which rests against the bottom of a vertical 

 V-groove fixed to the support u. The weight of the pendu- 



