OFFICIAL INSTRUCTIONS. 
XXV 
advancement of science in general. Amongst other subjects of scien- 
tific inquiry, you will particularly direct your attention to the variation 
and inclination of the magnetic needle, and the intensity of the mag- 
netic force ; you will endeavour to ascertain how far the needle may 
be affected by the atmospherical electricity, and what effect may be 
produced on the electrometer and magnetic needle on the appearance 
of the Aurora Borealis. You will keep a correct register of the tem- 
perature of the air, and of the sea, at the surface and at different 
depths. You will cause the dip of the horizon to be frequently 
observed by the dip sector, invented by Dr. Wollaston ; and ascer- 
tain what effect may be produced by measuring that dip across fields 
of ice, as compared with its measurement across the surface of the 
open sea. You will also cause frequent observations to be made for 
ascertaining the refraction, and what effect may be produced by 
observing an object, either celestial or terrestrial, over a field of ice, 
as compared with objects observed over a surface of water: together 
with such other meteorological remarks as you may have opportunities 
of making. You are to attend particularly to the height, direction, 
and strength of the tides, and to the set and velocity of the currents ; 
the depth and soundings of the sea, and the nature of the bottom ; 
for which purpose you are supplied with an instrument better calcu- 
lated to bring up substances than the lead usually employed for this 
purpose. 
And you are to understand, that although the finding a passage from 
the Atlantic to the Pacific is the main object of this Expedition, yet, 
that the ascertaining the correct position of the different points of the 
land on the western shores of Baffin’s Bay, and the different observa- 
tions you may be enabled to make with regard to the magnetic influ- 
