548 PROCEEDINGS OP SECTION E. 



6.— SOUTH AUSTEALIAN LATITUDE AND LONGITUDE.-A 

 SHORT ACCOUNT OF THE DETERMINATION OF GEO- 

 GRAPHICAL POSITIONS OF PLACES IN SOUTH AUS- 

 TRALIA. 



By C. HOPE HARRIS. 



(Communicated by the Surveyor-General, W. Strawbridge, Esq., I.S.O.) 



Part I. — Longitude. 



The first determinations of latitude and longitude of places in 

 South Australia were made by its discoverer, Matthew Flinders, R.N. 



This distinguished navigator mapped the entire coastline from 

 Point Fowler to Encounter Bay, including the north coast of Kangaroo 

 Island; and has recorded, in the journal of his voyage to "Terra 

 Australis," vol. i., 1802, the results of many astronomical observations 

 by which the prominent features embraced in his survey were geo- 

 graphically fixed. 



The best results were obtained with a sextant and artificial horizon' 

 on shore. Longitudes were deduced from local time, observed by 

 altitude of sun and stars, compared with Greenwich time shown by 

 chronometers, the accepted longitude of a lighthouse at King George's 

 Sound being taken into account in passing ; also the longitude of 

 Fort Macquarie when Sydney was reached. Special determinations 

 were made on a hill west of Port Lincoln, which, on comparison, are 

 found to be in close agreement with latest Admiralty charts. 



On board the sloop ipvestiqntor observations were taken at Holdfast 

 Bay and Kangaroo Head, from which the position of Mount Lofty 

 was fixed as being in latitude 34° 59' and longitude 138° 42'. The 

 figures are given in the journal to minutes only, but the original chart 

 by Flinders is correct within a few seconds of the true position. Some 

 people may regard this as only a coincidence, but it is interesting to 

 note that the same exactitude is evidenced by the figures given for the 

 extremity of Cape Willoughby, at the east end of Kangaroo Island, 

 viz., latitude 35° 58', and longitude 138° 08', which cannot be more 

 correctly stated at the present time. 



The next important determination of longitude concerned the 

 boundary between South Australia and Victoria. 



In December, 1839, Mr. J. C. Tyers, a New South Wales surveyor, 

 previously of the Admiralty surveying ship Beatrice, was appointed to 

 fix the position of the 141st meridian, near the mouth of the Glenelg 

 River. This jMr. Tyers did in three ways. First, by chronometric 

 measurement from Sydney to Portland Bay on board the vessel 

 Pyremus ; second, astronomically, by observation of lunar distances 

 m.ade in the locality with sextant and artiHcial horizon ; third, by rapid 

 triangulation from Batman's Hill, Melbourne, to the Glenelg River. 

 The longitude thus obtained for the eastern bank of the mouth of the 

 river was — by chronometers, 141° 01' 43" ; by lunars, 141° 01' 59" '. 

 by triangulation, 141° 00' 28"; the mean being 141° 01' 23".3. The 



