54 PROCEEDINGS OF SECTION A. 



and Soutiiport (Queensland) were connected by a homogeneous system 

 of longitude measurements carrying the same weight as that of all 

 other links of the chain. But this connexion is the oldest and, possibly, 

 in parts, the weakest, considering that it was measured in five steps 

 by eight different observers with different instruments and methods, 

 and that three of these five arcs have not been verified, while the other 

 two, Singapore-Madras and Melbourne-Sydney, which were tested by 

 repeated measurements, gave results differing by more than half a second 

 of time. 



It should be recognised, therefore, that there can be no justification 

 at present for modifying the margin of uncertainty which was assigned 

 to our longitudes in 1894, and that the whole of the longitude work 

 which has been done since by Col. Burrard and Col. Lennox Conyngham, 

 by Dr. Klotz and his assistant, and by Profs. Albrecht and Wanach, 

 important as it is, especially for us, from the point of view that by it 

 the position of our fundamental meridians could be established with 

 greater precision and accepted with greater reliance, must remain of 

 very little value to us until we shall have settled more satisfactorily 

 the longitudinal interval between Madras and Southport. 



What is needed is a re-determination of the Australian arcs and of 

 the intervals Port Darwin-Singapore and Singapore-Madras, thoroughly 

 carried out with all the refinement of the present day practice both in 

 regard to instrumental means and system of procedure. 



To accomplish this task we require two competent observers who 

 should be supplied each with an equipment precisely similar, consisting 

 principally of — 



Transit instrument ; object glass about 3* ; focal length, from 

 30 to 36 inches, provided with travelling wire micrometer, 

 reversing apparatus and usual accessories. 

 One pendulum clock and one chronometer, with break-circuit 



electrical arrangements. 

 Chronograph. 



A portable wooden transit hut. 

 The whole being specially designed to serve this particular class of work. 

 The stations to be occupied on the direct chain are — 

 Southport (Queensland). 

 Sydney. 

 Melbourne. 

 Adelaide. 

 Port Darwin. 

 Singapore. 

 Madras. 

 The itinerary should be carefully arranged so as to enable the 

 observers to exchange places at each pair of stations with the least 

 possible inconvenience or loss of time, and with due regard to the sea- 

 sonal weather conditions. 



