[Pkoc. Koy. Soc. VicroRiA 35 (N.S.), Pt. I., 1922.] 



Art. VII. — Gravity Determinations in Australia. 

 By E. F. J. LOVE, M.A.. D.Sc, F.R.A.S., F. Phys. Soc. Lond. 

 [Read 13th July, 1922.] 



§ 1. Introduction. 



The recent appointment, by the National Research Council of; 

 Australia, of a committee to report on the subject of a gravity survey 

 of the continent, necessitates a critical discussion of the determina- 

 tions of the gravitational acceleration which are already in existence.. 

 As regards those for Brisbane, Hobart and Perth, little can be said; 

 each depends on a single set of observations, and, until, checked, must 

 be regarded as provisional. The work of Budik at Brisbane and 

 Hobart is considered by Helmerti to be affected by a mean error of 

 +0-010 cm. sec-2; to that of Alessio, at Perth2, the mean error +0-007 

 may be assigned. We therefore have, as provisional values only — 

 For Brisbane : f/.-^OTQ - 148 t 0-010 cm. sec-^ 



„ Hobart : gr^ 980-441 1 0'OIO „ „ 



„ Perth : g= 979-374 1 0-007 „ 



The case is different as regards the Melbourne and Sydney observa- 

 tories. For each of these we have a determination by means of Kater 

 pendulums, and several others by means of half-seconds pendulum, 

 both of the von Sterneck and Potsdam types. Suitable averaging of 

 these should therefore furnish definite values of g for both stations; 

 also of their difference, which has an importance of its own, as it has 

 already served, 3 and may possibly serve again, as a sort of " Funda- 

 mental Interval," for the calibration of gravimeters of statical type. 



An error pointed out by Helmert (I.e.) necessitates a partial re- 

 vision of the Kater pendulum reductions; this constitutes §2. §3 con- 

 tains the evaluation of g for the two observatories, and §4 deals with the- 

 gravitational anomalies. The Appendices contain details which it seemed 

 advisable to keep apart from the main paper. The notation is that in 

 general use among geodesists. The methods of the theory of errors are- 

 used in the computing; the small quantities preceded by the sign ± are 

 in all cases mean error. 



§ 2. Revision of Results of Observations with 

 Kater Pendulums. 



Helmert (I.e.) has taken exception to the formula employed, both 

 by Baracchi and myself,* in the reduction of our observations to the- 



1. Assoc. Geodes. Int., compt. rend. 13 ieme conf. gen.; II. e vol., 1901.- 

 Prequent reference is made to this paper. 



2. His work at Perth and at Melbourne is about on a par ; the latter 

 is discussed in §3. 



3. Threlfall and Pollock, Phil. Trans. 193 A, 1900. 



4. Proc. Roy. Soc. Vict., 1893, p. 168; do., 1894. p. 8. 



