218 



T. GRAY ON A SE1SMOGEAPHIC APPARATUS. 



15. On Gray and Milne's Seismographic Apparatus. 

 By Thomas Gray, Esq., B.Sc, F.B.S.E. (Bead March 7, 1883.) 



The apparatus a description of which forms the chief subject of 

 the present paper, is intended to give a complete record of the nature, 

 magnitude, direction, and frequency of the motions of a point of the 

 earth's surface during an earthquake, and at the same time to record 

 the time of occurrence and the duration of the earthquake. The 

 apparatus has been made by Mr. James White, Glasgow, and is to 



Fig. 1, 



■Gray and Milne's Seismographic Apparatus as set up, 

 (Scale about one twelfth.' 



be used by Prof. Milne in his investigations as one of the committee 

 appointed by the British Association for the investigation of the earth- 

 quake phenomena of Japan. 



