280 APPENDIX. 



their future observations, and to increase the probability of the ob- 

 servations of both being preserved. 



13. We have caused a great variety of valuable instruments to be 

 put on board the ships under your orders, of which you will be fur- 

 nished with a list, and for the return of which you will be held respon- 

 sible. Among these are instruments of the latest improvements for 

 making a series of observations on terrestrial magnetism, which are at 

 this time peculiarly desirable, and strongly recommended by the Pre- 

 sident and Council of the Royal Society, that the important advan- 

 tage be derived from observations taken in the North Polar Sea, in 

 co-operation with the observers who are at present carrying on a uni- 

 form system at the magnetic observatories established by England in 

 her distant territories, and, through her influence, in other parts of the 

 world ; and the more desirable is this co-operation in the present year, 

 when these splendid establishments, which do so much honour to the 

 nations who have cheerfully erected them at a great expense, are to 

 cease. The only magnetical observations that have been obtained very 

 partially in the Arctic regions are now a quarter of a century old, and 

 it is known that the phenomena are subject to considerable secular 

 changes. It is also stated by Colonel Sabine that the instruments and 

 methods of observation have been so greatly improved, that the earlier 

 observations are not to be named in point of precision with those which 

 would now be made ; and he concludes by observing, that the passage 

 through the Polar Sea would afford the most important service that 

 now remains to be performed towards the completion of the magnetic 

 survey of the globe. 



14. Impressed with the importance of this subject, we have deemed 

 it proper to request Lieutenant-Colonel Sabine to allow Commander 

 Fitzjames to profit by his valuable instructions ; and we direct you 

 therefore to place this important branch of science under the immediate 

 charge of Commander Fitzjaines ; and as several other officers have 

 also received similar instruction at Woolwich, you will therefore cause 

 observations to be made daily on board each of the ships whilst at sea 

 (and when not prevented by weather and other circumstances) on the 

 magnetic variation, dip and intensity, noting at the time the tempera- 

 ture of the air, and of the sea at the surface and at different depths ; 

 and you will be careful that in harbour and on other favourable occa- 

 sions those observations shall be attended to, by means of which the 

 influence of the ship's iron on the result obtained at sea may be com- 

 puted and allowed for. 



