LATITUDE OF THE SYDNEY OBSERVATORY. 97 



of the mean latitude at Sydney, 



have been calculated for 



the period 1905 July 1 to August 



2. 



Greenwich. 



<f> — cf) 



Mean Noon. 





1905 July 1 



— 0*134 



„ 5 



— 0*138 



„ 9 



— 0*142 



„ 13 



— 0*145 



„ 17 



— 0*147 



„ 21 



— 0*149 



„ 25 



— 0*150 



„ 29 



— 0*151 



„ 33 



— 0*151 



From the above data the latitude variation, for the epoch 



1905 July 12, can be found by inspection. Applying this 



correction, with sign changed, to the preceding value of </>, 



we obtain the mean latitude of the Sydney Meridian 



Instrument. 



<£ = - 33° 51' $1"55 ± "06 



4. Conclusion. 

 From a combination of all the available data, it must be 

 conceded that the accepted value of the mean latitude of 

 the Sydney Observatory is numerically too small. The 

 probability is that the latitude now adopted is within one 

 quarter of a second of the correct value, but, until further 

 evidence is forthcoming, an alteration in the published 

 value would be unjustifiable. This adopted latitude how- 

 ever can only be taken as provisional, and not as a definitive 

 value of this important co-ordinate. A definitive deter- 

 mination of the latitude of the Sydney Observatory is 

 worthy of due consideration. If it were ever decided to 

 undertake such work, then the observations should be made 

 at intervals extending over a long period of time, so that 

 the data could be used not only for the determination of 

 the mean latitude, but also for an investigation into the 

 variation of this co-ordinate. For this purpose the author 

 would advocate the construction of an instrument specially 

 for the object in view. 



G— Dec. 6, 1905. 



