34 Experimental Philosophy. [Lecture 3. 



and another passing vertically through the north 

 and south points: helikewise found that atdifferent 

 distances, the position being the same, the tangents 

 of the angles of deviation were inversely propor- 

 tional to the cubes of the distances, and directly 

 proportional to the cubes of the diameter of the 

 attracting ball. 



But the most remarkable result obtained in 

 the course of these experiments (with the excep- 

 tion of the discovery of the plane of no attraction 

 above referred to) was, that the poicer of an at- 

 tracting body is independent of the mass of that 

 body ; a simple tin spherical shell of any given 

 dimension, acting equally as powerful as a solid 

 iron ball of the same diameter ; which is another 

 striking instance, in addition to many others, 

 of the analogy that subsists between the mag- 

 netic and electric attractions. Mr. Barlows ex- 

 periments, we understand , are not yet completed : 

 but it is hoped he will soon lay his most interest- 

 ing results before the woVld; as they will, doubt- 

 less, admit of an important practical application, to 

 the magnetism of iron in ships, and its effect upon 

 the direction of the needle in the ship's compass. 



