King. — On Neiv Zealand Mean Time. 443 



In addition to these chronometric and telegraphic deter- 

 minations, there have been three " absolute " determinations 

 — that is, determinations by means of observations of moon 

 culminations, &c. Before the present Observatory was built, 

 Captain Carkeek, with the view of ascertaining the longitude 

 of the old time-ball tower, conducted for many years a series 

 of observations in the shape of lunars, eclipses of Jupiter's 

 satellites, lunar eclipses, and moon culminations. 



Then, in 1869, 1870, and 1871, Chief Surveyors J. T. 

 Thomson and Henry Jackson, at their respective private 

 observatories at Eockyside (Caversham, Dunedin) and the 

 Hutt, by observations of moon culminations determined the 

 longitudes of those points. Having done so, they settled by 

 means of the electric telegraph the difference between the 

 longitudes of their two observatories, as a check upon their 

 independent determinations. Mr. James McKerrow, after- 

 wards Surveyor-General, assisted Mr. Thomson at Rockyside 

 in this important branch of the work. 



By triangulation from the old time-ball site to the Wel- 

 lington Observatory, and from Mr. Henry Jackson's private 

 observatory to Wellington Observatory, values were thus ob- 

 tained for the longitude of Wellington Observatory. 



Finally, in 1874-75, Major H. S. Palmer, B.B., chief of 

 the English expedition to New Zealand for the observation 

 of the 1874 transit of Venus, conducted a series of observa- 

 tions at Burnham (his observing-station in Canterbury) for 

 the determination of the longitude of that place. Professor 

 C. H. F. Peters, chief of the United States Transit of Venus 

 party, about the same time made similar observations for 

 longitude at his station at Queenstown, Lake Wakatipu. 

 Then these two points, with Mr. Heale's temporary observa- 

 tory at Auckland, the Colonial Observatory at Wellington, 

 and Mr. Thomson's observatory at Caversham, were con- 

 nected by telegraph, with the object of ascertaining their 

 respective differences of longitude. Major Palmer himself 

 came to Wellington and conducted the work necessary for fix- 

 ing the longitude of the Wellington Observatory on this basis. 



The results of these absolute determinations (or, to use 

 Major Palmer's term, "approximate absolute determina- 

 tions ") were as follows : — 



(1.) Captain Carkeek's approximate absolute,* 11 h. 39 m. 

 15-75 s. E. 



(2.) Messrs. Thomson and Jackson's approximate abso- 

 lute,* 11 h. 39 m. 15-31 s. E. 



* For an account of Captain Carkeek's and Messrs. Thomson and 

 Jackson's determinations see Messrs. Thomson and Jackson's report 

 to Government, Appendix to Journals of House of Representatives, 

 G.-No. 23, 1871. 



