110 A SUMMER VOYAGE TO THE ARCTIC 



Sydney on September 26, all the 48 persons constituting the 

 passengers and crew returning well and without accident. 



Some investigations in two lines of terrestrial ])hysics were 

 carried out by the writer in connection with the work of Pro- 

 fessor Ikirton's party. At each of the stopping jtlaces where 

 time permitted, magnetic observations were made, determining 

 the deviation of the compass needle from true north, the dip of 

 the dipping needle, and the force of the earth's magnetism. Two 

 of the stations were near enough to the magnetic North Pole of 

 the earth to cause the dipping needle to stand within six degrees 

 of the vertical. The Greenland stations were so well to the east 

 of the magnetic pole that the compass needle pointed more 

 nearly west than north. The horizontal magnetic force in these 

 regions is very weak on account of the great dip, so that mag- 

 netic disturbances caused considerable changes in the needle, a 

 change of over four degrees being noted in a single day at one 

 point. For the same reason the ship's compasses were irregular. 

 A comparison of these results with earlier magnetic observations 

 made in these regions clearly indicates the direction of change 

 at present going on. At all the stations from Halifax, Nova 

 Scotia, to Umanak, Greenland, the westerly declination, the dip^ 

 and the total magnetic force are all diminishing. At several 

 points also pendulum observations for the measurement of the 

 force of gravity were made. This force increases from the equator 

 to the poles, and, following the theorem of the French mathema- 

 tician, Clairaut, the amount of flattening at the poles of the earth 

 may be computed by comparing the force of gravity at different 

 latitudes. By a well-known law, the time of oscillation of a 

 pendulum will be proportional to the square root of the force of 

 gravity ; so that by comparing the time of oscillation of the same 

 pendulum at different places the relation of the force of gravity 

 may be obtained. Comparatively few such observations have 

 been made in high latitudes, where they have great weight in 

 the problem of the figure of the earth. 



[The illustrations acenmpanying the. foregoing article are from photographs Vjy Pro- 

 fessor A. E. Burton and other members of the party.] 



