I am indebted, generally, also to the Government Railway officials in New Zealand, 

 and to the officials of the Government Telegraph Service in particular, for the use of 

 a direct cable line from Christchurch to Wellington while rating the clock at Christ- 

 church from the Hector Observatory. Not least am I indebted to the sympathetic 

 attitude of the Prime Minister and the Hon. H. D. Allen, without which little could 

 have been done. Most of all, I have to thank Mr. C. E. Adams, Government Astronomer 

 of New Zealand, who took many of the necessary observations in New Zealand, reduced 

 them, and lent other valuable assistance, and Professor T. H. Laby for the loan of a 

 large induction coil and other apparatus, and for valuable help at odd hours of the 

 night. 



In Australia, the list of those to whom I am indebted is hardly less large. This 

 includes Professors Pollock and Sir Edgeworth David in Sydney and Professor Lyle, 

 Mr. Baracchi and Mr. Merfield at Melbourne. In particular, I have to thank Mr. Merfield 

 for taking and reducing the necessary time observations for rating the clock. 



Lastly, but by no means leastly, I have to thank Captain F. P. Evans of the Union 

 Steamship Company for the care and trouble taken in the stowage of the instruments 

 on their voyage from Australia to San Francisco. 



THE PENDULUMS. 



The apparatus lent by the Central Bureau at Potsdam was of Colonel von Sterneck's 

 pattern,* three half-second invariable pendulums and one variable auxiliary pendulum, 

 each swinging from its agate knife-edge on a separate agate plane. 



The observing pendulums supplied were numbered 5, 7 and 21. Of these, No. 21 

 was of brass by Stu'ckrath, No. 7 of brass by Fechner and No. 5 of phosphor-bronze 

 also by Fechner. All were heavily gilt, were of similar construction (see Fig. 1) and 

 had nearly the same period of vibration. At Potsdam these were : 



No. 21 0-509746 seconds. 



5 0-508339 



7 0-508314 



In this form of apparatus the agate knife-edge B (see Fig. 1) is fixed on the 

 pendulum, and this rests in use on the corresponding agate plane carried by the 

 pendulum stand. On top of the pendulum is securely fastened, on the one side, a 

 small silvered glass mirror A, and, on the other (in reserve), a metal one. These may be 

 adjusted by screws so that they lie accurately parallel to the vertical plane through 

 the knife-edge. 



The auxiliary adjustable pendulum is used only to determine the flexure correction 

 for No. 21 and, for this, its period of vibration is adjusted till it is approximately equal 

 to that of No. 21. 



* This apparatus is described by Hucker in " Veroffentlichung des Kgl. Preuss. Geod. Inst., Neue 

 Folge, No. 11." 



