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XXXII. The Pendulum Accelerometer^ an Instrument for the 

 Direct Measurement anal Recording of Acceleration, By 

 F. W. Lanchester*. 



ONE of the problems connected with the testing of 

 locomotive vehicles is that of measuring and recording 

 the magnitude of the starting and stopping efforts, and 

 generally experimentally determining what may be appro- 

 priately termed the "ballistics of traction/'' 



The instrument that forms the subject of the present paper 

 has been designed to facilitate determinations of this 

 description with a sufficient degree of accuracy for the 

 ordinary purposes of the engineer, without involving any 

 special and expensive preparation. 



Fig. 1. 



PENDULUM ACCELEROMETER. 



(889 MODEL. 



I . 



A. Pendulum-bob. 

 B-C. Knife-edge supports 



D. Motion arm. 



E. Pencil arm. 



F. Pencil or stilus. 



G. Winding drum. 



Note to Jigs. 1 and 4. 

 H. Spool of paper. 

 J. Datum marker. 

 K. Dash-pot bracket. 

 L. Dash-pot piston. 

 M. Frame casting. 

 N. Levellinsr-screws. 



0. Anchorage screws. 

 P-Q. Clock-work. 

 li. Wind. 

 S. Handle. 



The fundamental principle on which the instrument works, 

 is that the effect of the algebraic sum of tractive forces and 

 resistances on the vehicle as a whole, is shared proportionately 

 by every portion of its mass, and that consequently the 



* Communicated by the Physical Society : read June 16, 1905. 



