226 SCIENTIFIC RECORD FOR 1884. 



the Naval Observatory; C. G. Rockwoofljr., of Princeton; and W. M. 

 Davis, of Harvard College. Plans were arranged looking to the pro- 

 curing of more accurate non-instrumental observations, and to the ulti- 

 mate establishment of such instrumental observations as might be 

 found practicable. To this end subcommittees of those present were 

 appointed to consider the selection of instruments and the location of 

 stations, &c., which committees are expected to report at a subsequent 

 meeting of the conference. 



At the Montreal meeting of the British Association, in August, 1884, 

 a grant of £75 was made for the investigation of earthquake phenom- 

 ena in Japan, and £25 for volcanic phenomena at Vesuvius. {Science, 

 IV, 263.) 



SEISMOMETRY. 



An underground observatory has been established by Professor Milne 

 at Takashima, near JSTagasaki, in a coal mine whose workings extend 

 beneath the island and the sea and have a total length of about 70 

 miles. It is proposed to carry on observations of the motions of the 

 soil by means of microphones placed in the solid rock, by instruments 

 to measure the '• earth tremors," and by delicate levels, together with 

 barometric and thermometric observations and observations of the es- 

 cape of fire-damp, with the hope of determining whether any of these 

 phenomena are connected with one another. 



In seismometry i^roperthe most imjjortant work is a memoir onEarth- 

 quake Measurement by J. A. Ewing, published as ^STo. 9 of the Me- 

 moirs of the Science Department of the University of Tokio. It con- 

 sists of seven chapters, with twenty-four plates, of which fourteen re- 

 late to the instruments and ten are copies of the records made by them. 



The first chapter is devoted to a concise statement of the theory of 

 earthquake motion ; the difference between the normal and transverse 

 vibrations, both being usually present ; the greater velocity of the for- 

 mer, by which the two kinds of vibrations arising from the same shock 

 become separated at a distance from their source ; the effect of reflec- 

 tion and refraction at the bounding surfaces of the media traversed ; 

 the want of agreement between the direction of the wave within the 

 ground and the motion impressed upon a particle at the surface; that 

 is, in general, to the peculiarities of the -phenomena to be observed. 



In tlie second chapter, after theoretically determining the kinetic and 

 static conditions to be fulfilled by the steady point of a seismometer, 

 the author applies them to the horizontal i^endulum, describing in detail 

 the seismometer based upon it, and the improvements introduced by 

 himself and others. The instrument consists essentially of a heavy 

 mass pivoted through its center of inertia to one side of a light frame, 

 which itself is so supported as to admit of motion with little friction 

 about a vertical axis parallel to the line of support of the bob. The 

 magnified record is made by a pointer attached to the frame and tracing 



