THE 

 LONDON, EDINBURGH, and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



[FIFTH SERIES.] 



MA T 1890. 





XLI. A New Form of Electric Chronograph. By Rev. 

 FitEDEKiCK J. Smith, M.A., Millard Lecturer in Mechanics 

 and Physics, T?*inity College, Oxford*. 



[Plate IX.] 



DURING the last two years a research has been carried 

 on by me on the subject of the acceleration-period of 

 explosions!. In order to deal with the time-measurements 

 which arose out of the investigation, it was found necessary 

 to devise a chronograph which would register a large number 

 of events following each other after small periods of time. As 

 the chronograph used in these experiments has been found to 

 be of use in other branches of scientific work, viz. in deter- 

 mining the velocity of shot, and many physiological time- 

 measurements, I beg to offer an account of its construction 

 and use to the readers of the Philosophical Magazine. The 

 instrument has been called the Electric Tram Chronograph, 

 because the moving surface is carried upon wheels running 

 on rails. 



The instrument has, in common with other forms of time- 

 measuring instruments, a moving plate on which traces are 

 made by means of electromagnetic styli. In other respects it 

 greatly differs from other forms of time-measuring instruments. 



In order that an electric chronograph may be of general 



* Communicated by the Author. 



f Proceedings of the Royal Society, xlv. p. 451. 



Phil. Mag. S. 5. Vol. 29. No. 180. May 1890. 2 G 



