Ross.—On the Declination of the Magnetic Needle. 7 
of 1857, to the Commissioners of the Waste Land Board, by Mr. J. T. Thomson, 
Chief Surveyor of Otago, and is as follows :—“ In a district like this, situated 
on one of the great volcanic zones, where terrestrial galvanic currents may be 
supposed to prevail, it will be correctly surmised that the surface sometimes 
indicates forcibly the presence of magnetie disturbance. This disturbance was 
more or less sensibly indicated in our observations, but the most remarkable is 
on the Bluff Peninsula, as will be seen by the following :— 
“ On the summit of Bluff - - variation 6? 54' E. 
“Thirty feet north of the same - "а 9° 36’ W. 
“Thirty feet west of the same - „ 5° 04’ E. 
“ Thirty feet east of the same - » 40 44’ Е.” 
To this report is appended the following note :—“ The bearing of the magnet 
is affected in all parts of the Province where hard compact traps crop out. 
These are found principally on the higher parts of ridges and mountains.” 
Proceeding northward, we find at Kuriwao Hill the declination to be 
13? 53’ 27" E. ; at Toetoes, 14° 19’ 32”; and at Chimney Hill, 14° 56’ 50". 
From this to Port Chalmers no remarkable variation in declination has been 
recorded. I may observe, however, that at all stations on land near the sea- 
board the declination is less than it is shown to be at sea on the Admiralty 
charts, the mean difference, after the declination has been corrected for 
difference of dates of observations, amounting to nearly 2 degrees. At Port 
Chalmers the declination observed by Mr. Kettle, in 1846, was 16? 10' E. ; 
by Captain Stokes, in 1850, 15° 40’ E. ; in 1864, by Mr. McKerrow, it was 
15° 40’ 08” E., so that in the four years, 1846 to 1850, a decrease of 30’ is 
shown ; while in the fourteen years, 1850 to 1864, no change whatever has 
been observed, the results given by Mr. McKerrow being virtually the same 
as those given by Captain Stokes. 
North of Port Chalmers the disturbing force at many of the stations is 
very considerable. In the immediate vicinity of the port at Mihiwaka the 
declination is shown to be 19° 20’ 48" E.; at Flagstaff it is 14° 14’ E. ; in 
Nenthorn District, at Mount Stoker, it is 35° 21' 44" E. In recording this 
observation in his field book, Mr. McKerrow made the following entry :— 
* Hard bluestone boulders on Mount Stoker.” At Highlay Hill the decli- 
mation is 2° 24’ 32" E.; in Hawksbury District, at Mount Watkins, it is 
3° W. ; and at Taieri Peak, a few miles to the north, it is 104° 47 Е. In 
Moeraki District, at Trig. Station O, it is 26° 10’ E. ; and at Trig. Station P 
it is only 50’ E. In Kauroo District, at Mount Difficulty, the declination is 
1° 02’ W.; at Trig. Station L, 13° 30’ E. ; at Trig. S, 22° E. ; at Black Cap, 
8° 54’ W. These four stations are included within a radius of about two and 
a-quarter miles ; and, lastly, the declination at Kauroo Hill, about five miles 
N.E. of Black Cap, is 41? 03' 35" E. 
