Observations zuith Katers Pendnhnns. 163 



were undertaken, in consequence of discordance in the results of 

 1882. 



They arrived in Melbourne in November, 1892, and Mr. Ellery 

 made the necessary preparations for swinging them at the 

 Observatory, and had all the various parts mounted and adjusted 

 and ready for work by the middle of June last, when Mr. Love 

 started the observations. At about the same time Lieut. Elblein 

 of the Austrian warship -.Sa/^a, swung three |-second Pendulums 

 of Colonel von Sterneck's type, at the Meluourne Observatory, 

 thus connecting it with an independent basis, viz. : Vienna, where 

 the absolute value of the Force of Gravity was determined by 

 Professor Oppolzer. This increased the importance of the 

 Melbourne swings with the Kater's Pendulums, for their results 

 cf>uld be tested by two different series. It was decided in conse- 

 quence, to extend the operations further than it was originally 

 intended, taking for standard the re visionary work at Greenwich 

 and Kew, and thus establish a satisfactory basis to which other 

 Gravity determinations in Australia, made with Kater's or any 

 different form of pendulums, might be referred. The Melbourne 

 Observatory possessed all the necessary conditions for carrying 

 out the observations under the best advantages. 



The value of Gravity determinations by the differential method 

 depends on the invariability of the pendulums used. There is 

 evidence to show that when carefully handled, these pendulums 

 remain unchanged and may be swung without re-grinding the knife 

 edges for many years, and as the three Pendulums now employed 

 have not been intentionally altered, or known to have met with 

 any accident since Colonel Herschel swung them at Kew and 

 Greenwich in 1882, it may be expected that they are now in the 

 same condition as they were eleven years ago. Fortunately we 

 have the means of testing this condition by swinging them again 

 at Sydney, which it is to be hoped will be done, at the earliest 

 opportunity. 



The pendulums were swung in the eastern underground room in 

 the main building of the Melbourne Observatory, which, having a 

 stone pavement, offered all the required stability, and had also 

 the advantage of keeping a fairly constant temperature. The 

 clock by Shelton, the same as that used in England and India, 

 was fixed to the south wall of the room, and the Pendulum Stand 



m2 



