Geology of Hobart Town. 131 



The sun's parallax, derived from the combination of the 

 results obtained at Greenwich with those of our Observatory, 

 was 8 //- 93, while from the combination of those at the Cape 

 with the Pulkowa observations gave 8 //- 96. 



It is a matter of the highest scientific interest that the 

 results arrived at by the co.-operation of these four 

 observatories should correspond so nearly with each other, 

 so exactly with those deduced theoretically by Mons. Le 

 Verrier, and so nearly approaches that arrived at by 

 another distinct method by Faucoult, viz., from his. experi- 

 ments on the velocity of light. 



The distance of the sun arrived at from the Williamstown 

 and Greenwich observations is, according to -Mr. Stones', (of 

 Greenwich,) calculation, 91,512,649 miles, or over 3,000,000 

 of miles less than has hitherto been assumed. 



In conclusion, I may remark that satisfactory in the 

 highest degree as these results appear to be, astronomers are 

 looking forward to the transit of Venus, in 1874, to ratify 

 them or to determine with greater exactitude than the Mars 

 method is susceptible of, the more precise amount by which 

 our hitherto accepted distances of the sun requires to be 

 diminished. 



This transit of Yenus will take place soon after mid-day, 

 on December 9th, 1874. Melbourne is admirably situated 

 for observing it. European astronomers are already taking 

 steps to secure proper co-operation in the Southern Hemi- 

 sphere, and I trust that our Observatory, so liberally 

 furnished with some of the finest instruments in the world, 

 will do as well for science, and for the credit of Victoria, as 

 it was permitted to do in the determination of the Sun's 

 distance, in 1862. 



Art. XXXII. — Notes on the Geology of Hobart Town. 

 By Thomas Harrison. 



[Abstract. Bead 8th August, 1864.] 



Tasmania is, as it were, connected with Victoria by two 

 chains of islands, running in a northerly direction, respec- 

 tively, from Cape Portland and Cape Grimm to Wilson's 

 Promontory and Cape Otway. The lines of these two 

 chains are afterwards continued in the several mountain 

 systems of Tasmania and Australia. 



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