154 Transactions of the American Institute. 



polarity, or it is of north polarity south and the spear-end of the 

 needle of south polarity. It matters not much which hypothesis you 

 adopt, but we will call the spear-end of the needle its north pole, and 

 the geographic north the south magnetic pole. 



If, after assuming these circumstances, our experiments conform to 

 such hypotheses, we have an honest reason for thinking that, in the 

 main, their existence is highly probable; and, this much established, 

 we can, from this knowledge, devise other and more searching obser- 

 vations and experiments, whose agreement or non-agreement with 

 our hypothesis will carry more conclusive evidence as to the truth or 

 falsity of our suppositions ; and so, step by step, we ascend to the 

 widest and surest generalizations of physical science. This? indeed, 

 is the method of arriving at all the fundamental laws of natural phi- 

 losophy, and, if not satisfactory to the strict scholastic logician, we 

 only say that this is all that we can do, and show its value by point- 

 ing to the results obtained by such methods of inquiry. We start with 

 imagining existences, and banish these dreams, one after another, 

 until one is called up which conforms to the actual experiences of 

 observation and experiment. The fault of the ancients was not that 

 they wanted vivid imaginations — quite otherwise — but that they 

 were satisfied that their imaginings should remain " of such stuff as 

 dreams are made of," and never endeavored to find their realities in 

 the material world, and give them embodiment in those entities which 

 exist all around us. The search for these entities is the pursuit of 

 science, and the finding of them is its object. 



Thus we will proceed in our work. These parallel white cords, 

 which you observe stretched above the floor, lead to the point in the 

 earth where, in our imagination, we have placed its magnetic pole. 

 We will soon see that there are other methods of very accurately 

 determining the direction of these lines, and we will also find that 

 our ideas have to be somewhat modified as to their paths, for we 

 shall see that instead of being straight lines they really lead to the 

 pole in curves. But remember that we are indulging in our first 

 reverie, and this can but be a vague image of the truth. But all of 

 the conditions necessary for the realization of our reverie are already 

 clearly in your mental vision, and we can at once proceed to seek if 

 any resemblance to it in nature really exists. 



I take this bar of soft iron, and, holding it horizontally, I bring one 

 end of it near the center of the lantern needle. You now see in the 

 circle the end of the magnified rod, and you observe that the needle 

 does not rotate. The bar is entirelv devoid of magnetism. But 



