Fisher on the Variation of the Compass. 105 



the purpose, consisted of a long chain of copper connected to a 

 rope by means of glass arms placed about a foot distant from 

 each other; by means of this rope, one extremity of the chain ter- 

 minated by a long tapering copper rod, tapered with platina, 

 was elevated above the main-top-royal-mast-head. 



On no occasion, however, but one, could the presence of 

 electricity in the atmosphere be detected; this was on the 21st 

 July, the ships were at that time firmly beset with ice on the 

 north coast of Spitzbergen, in latitude 80°.15' N. ; during the 

 whole of the day the electric chain conductor was attached to 

 the main-royal-mast-head, and in the forenoon, which was per- 

 fectly calm, no symptoms of electricity was indicated by any of 

 the electrometers, but in the afternoon negative electricity was 

 detected ; for, on applying a small gold leaf electrometer to the 

 conductor, a divergence of the leaves took place, which was in- 

 stantly increased by the application of a stick of sealing wax 

 previously excited. Long diverging clouds from the east- 

 ward. By azimuths, taken immediately afterwards, the westerly 

 variation was rapidly increasing, as appears from the following 

 results of the observations taken at equal intervals of not more 

 than ten minutes : — 



O / " 



22.54.66 W. 

 23. 4.40 — 

 23.20.2 — 

 23.53.52 — 



Each of the observations is a mean of five azimuths, taken 

 with Kater's azimuth compass, fixed on a tripod stand on the 

 ice ; the corresponding altitudes of the sun's upper and lower 

 limb were taken alternately by myself and Mr. Dealy of the 

 Dorothea, with Troughton's eight-inch sextants and false horizon. 

 This rapid increase in the variation at the time of detecting the 

 electricity, is exceedingly remarkable. The weather was per- 

 fectly calm, and the sun's altitudes were taken under the most 

 favourable circumstances ; nor can it be attributed to any ex- 

 traordinary refraction in the atmosphere, which appeals by 



