41 



On comparing Br. Neumeyer's chart for the epoch 1858- 

 1864 with the revised curves of equal magnetic variation 

 issued by the Admiralty about a year ago, we find strong 

 evidence to the same effect. The Admiralty curves are a 

 generalisation from a vast body of observations collected at 

 the Hydrographer's Office, and may possibly not include 

 any recent observations in Tasmania. Indeed, I have 

 reason to know that they do not. Dr. Neumeyer's Hobarton 

 curve of lOdeg. 25min. E. for 1863, falls between the curves 

 of 9deg. and lOdeg. E. on this map, which is dated 1880, some- 

 where near 9deg. 45min. I have inserted these lines in a map 

 which is on the table. We may gather from the whole 

 evidence that the line of no variation, which cuts West Aus- 

 tralia, is now moving eastward. Twenty years ago it was 

 moving westward. I am indebted to Mr. Calder for an ex- 

 tremely curious extract from Tasman's journal, which proves 

 that, in his time, it was far to the westward again. That great 

 navigator notes, in December, 16i2, " when you come from 

 west, and find the N, W. variation suddenly decrease, you may 

 then look out for the land. Near the coast here the needle ijoints 

 due north."" 



That is to say, the line of no variation which at present cuts 

 the parallel of 42deg. S., in ISOdeg. E., or thereabouts, was 

 in 1642 very near the West Coast of Tasmania, and, therefore, 

 fully 14deg. more easterly than it is now. The variation of 

 the needle is a matter of greater practical consequence here 

 than is generally supposed. The district surveyors throughout 

 the colony, I am told, make use of compass bearings only — 

 all grants of land are laid out by them ; all boundaries defined 

 by them. Now, if I am thus informed correctly, any gentle- 

 man who may have had given to him in 1863 a line due N. as 

 his boundary, if he ran it again by compass to-morrow, would 

 find himself at the end of one mile, 50 yards off the line. 



This consideration will show plainly that the compass ought 

 never to be trusted for such purposes. There are many other 

 considerations which point to the necessity of putting the 

 surveys of this colony upon a different basis. 1 alluded to 

 this pointedly in my address to you in April last. I will only 

 now express my full concurrence with the weighty opinion 

 expressed, I observe, by our colleague and Vice-President, Mr. 

 Stephens, in a correspondence just laid before Parliament,* 

 that, " if it be long delayed inextricable confusion will be the 

 probable, if not certain, result." 



Postscrij)t. — In the discussion which ensued upon this paper, 

 one of the Fellows present remarked that the variation is still 

 increasing at Melbourne, and I thought it due to the Eoyal 



* Sessional paper, No. 101, New Map of Tasmania. 



