SEISMOLOGICAL REPORTS 51 



RIVERVIEW COLLEGE OBSERVATORY, SYDNEY, N.S.W. 

 Rev. E. F. PIGOT, S.J., Director. 



The Seismological branch of the College Observatory begun 

 here some few years ago was opened in March, 1909, and since the 

 following month the seismometers Nos. 1 and 2 (see attached 

 sheet) have been recording continuously, while the pair of Stras- 

 burg Pendulums (No. 3) have been in operation since their erection 

 last June. The two former instruments have been briefly 

 described in a paper read before the Royal Society of New South 

 Wales, December, 1909 ; a description of the latter (with lantern 

 illustrations of details, as in the former case) formed the subject 

 of a short communication to Section A of the A.A.A.S., meeting 

 in Sydney. 



The accompanying sheet is explanatory to the Riverview 

 " Seismological Bulletins," which are pubhshed at intervals, giving 

 quantitative analyses of the disturbances of true seismic origin 

 recorded here. A detailed study of the records with reference to 

 other lines of research — e.g., periodic bradyseismic tilt movements, 

 the meteorological significance of certain forms ^ of microseismic 

 waves, etc. — has been also in progress for some time, the results 

 of which will be published later. 



Riverview College Observatory. 

 0= 33° 49' 49" S. 

 ,V = 10"- 4"' 38-'- E. 

 h = 4L9 metres. 



Seismological Bulletins — Notation Employed, Instruments, Reductions, etc. 

 Notation. — That of the Gottingen Geophysical Institute (slightly modified). 

 The following abbreviations are employed : — 



A. CHARACTER OF THE EARTHQUAKE. 



I. = perceptible ; II. = striking ; III. = very striking. 



d (= terrcB motus domesticus) ~ local. 



V {— ,, ,, viciHus) = near (less than 1000 km.) 



r (== ,, ,, remotus) = distant (1000 to 5000 km.) 



u (= ,, ,, iiltimus) = very distant (over 5000 km.) 



B. PHASES. 



P ( = iindcB primes) = 1st prelim, tremors (commencement). 



S ( = ,, secimdee) = 2nd ,, ,, ( ,, ). 



L ( = ,, longee) — " principal phase," long waves, Rayleigh waves 



(commencement). 

 M ( = ,, maxima) = maximum amplitude of L waves. 

 C ( = coda) =a prominent wave among the "after-tremors" 



(Nachlaufer). 

 F ( = finis) = last perceptible movement (non-microseismic). 

 PRi, PR2 SRi, SR., = 1st, 2nd reflected waves 



of P and S. 

 PS = so-called "Wechselwellen " — i.e., waves whose longitudinal character 



has been altered by reflection to transversal. 

 Mri. = L waves which have traversed the major arc. 

 Mill. = >> ,, ,, ,, minor ,, -fTTrR. 



