212 



PROCEEDINGS OF THE AMERICAN ACADEMY. 



The normal curve as determined is indicated in all these figures by 

 the dots spaced every 1000 units of B. 



Figure 7 exhibits the curves taken on October 4, 1906, and shown 

 in Table III. It will be seen that these curves are very much flatter 

 than those of the \ in. rod and the tV ii^- I'od which follows this one. 



100 



400 



Figure 9. [Table IV.] 



Curves showing variation of magnetic induction with different lengths of a 

 Bessemer soft steel rod of diameter 0.4763 cm. The numbers affixed to the 

 curves give the constant currents in amperes through the solenoid. 



Figure 8 shows the original curves of October 9, 1906, and presented 

 in Table IV. 



From the data of these curves Figure 9 was also drawn. This shows 

 the curves of constant cun-ent as the rod is increased in length. The 

 numbers afhxed to the curves give the current in amperes, so that the 



