196 



PROFESSOR C. G. KNOTT ON THE 



linear current follows a different law from that due to a helical current. Indeed, 

 it is impossible to magnetically saturate an iron wire by means of a linear 

 current. Further than this, experiments of the B type need no discussion. 



The maximum point in the curves of group A is a constant characteristic 

 of all similar cases, as will be seen by reference to the curves of groups C and 

 D. These represent further experiments with iron wires, in which is studied 

 more particularly the effect of tension upon the amount of twist. In the fol- 

 lowing tables there are three distinct series under each experiment correspond- 

 ing to three different tensions. The last column contains the tensions expressed 

 in grammes' weight. 



Group C. — Cross Section of Iron Wire = "00276 sq. cc. 

 Experiment I. Linear Current = "533 Amp. 



Helical Current, 



0-952 



1-657 



2-489 



3-039 



3-723 



5-198 



Tension. 



( 



561 



632 



632 



607 



523 



413 



1360 



Twist, . .< 



1013 



1148 



1161 



1097 



1013 



875 



712 



( 



1123 



1284 



1258 



1265 



1097 



923 



388 



Experiment II. Linear Current = L476 Amp. 



Helical Current, 



0-533 



0-952 



1-657 



2 489 



3-039 



3-723 



5-198 



Tension. 



( 



484 



1213 



1471 



1484 



1406 



1299 



1097 



1360 



Twist, . .< 



458 



1077 



1452 



1594 



1529 



1426 



1187 



712 



1 



439 



1045 



1503 



1658 



1684 



1561 



1323 



388 



Experiment III. Linear Current = 2 -41 2 Amp. 



Helical Current, 



0-533 



0-952 



1-657 



2-489 



3-039 



3-723 



5-198 



Tension. 



Twist, . -0< 



0484 

 0490 

 0394 



0877 

 1187 

 0923 



1332 

 1742 

 1394 



1445 

 1974 

 1723 



1510 



1974 

 1820 



1555 

 2019 

 1800 



1394 

 1800 

 1645 



1360 

 712 

 388 



