120 HEPORT— 188L 



Some interesting otDservations were made at Pulkova on a subject 

 cognate to that on which we are writing. M. Magnus Nyren contributed, 

 on February 28, 1878, an interesting note to the Imperial Academy of 

 St. Petersburg, entitled ' Erderschiitterung beobaclitet an einem feinem 

 Niveau 1877 Mai 10.'' On May 10 (April 28), 1877, at 4.16 A.M., 

 a striking disturbance of the level on the axis of the transit was observed 

 by M. Nyren in the observatory at Pulkova. The oscillations were 

 watched by him for three minutes ; their complete period was about 

 20 seconds, and their amplitude between 1"'5 and 2". At '±.35 a.m. 

 there was no longer any disturbance. He draws attention to the 

 fact that it afterwards appeared that one hour and fourteen minutes 

 earlier there had been a great earthquake at Iquique. The distance 

 from Iquique to Pulkova is 10,600 kilometers in a straight line, and 

 12,640 kilometers along the arc of a great circle. He does not posi- 

 tively connect the two phenomena together ; but he observes that if 

 the wave came through the earth from Iquique to Pulkova it must have 

 travelled at the rate of about 2'4 kilometers per second. This is the 

 speed of transmission through platinum or silver. 



M. Nyren thinks the wave-motion could not have been so regular 

 as it was, if the transmission had been through the solid, and suggests 

 that the transmission was through the fluid interior of the earth. 



It appears to us that this argument is hardly sound, and that it would 

 be more just to conclude that the interior of the earth was a sensibly 

 perfectly elastic solid ; because oscillations in molten rock would surely 

 be more quickly killed out by internal friction than those in a solid. 

 However, M. Nyren does not lay much stress on this argument. He 

 also draws attention to the fact that on September 20 (8), 1867, 

 M. Wagner observed at Pulkova an oscillation of the level, with an 

 amplitude of 3", and that seven minutes before the disturbance there 

 had been an earthquake at Malta. On April 4 (March 23), 1868, M. 

 Gromadzki observed an agitation of the level, and it was afterwards 

 found that there had been an earthquake in Turkestan five minutes before. 



Similar observations of disturbances had been made twice before, 

 once by M. Wagner and once by M. Romberg ; but they had not been 

 connected with any earthquakes — at least with certainty. 



Dr. C. W. Siemens has invented an instrument of extraordinary 

 delicacy, which he calls an 'Attraction-meter.' An account of the 

 instrument is given in an addendum to his paper ' On determining the 

 depth of the sea without the use of the sounding-line' (' Phil. Trans.,' 

 1876, p. 659). We shall not give any account of this instrument, because 

 Dr. Siemens is a member of our committee, and will doubtless bring any 

 observations he may make with it before the British Association at some 

 future time. 



III. Hemarlcs on the present slate of the suhject. 



Although our experiments are not yet concluded, it may be well to 

 make a few remarks on the present aspects of the question, and to state 

 shortly our intentions as to future operations. 



Our experiments, as far as they go, confirm the results of MM. 

 d'Abbadie and Plantamour, and we think that there can remain little 



' Bull. Acad. St. Pet., vol. 24, p, 567. 



