Magnetic Tractive Force, 

 Table IV. — Glass-hard Wolfram Steel. 



163 



Current, 



H. 



B. 



I. 



B 



G. 



Difference. 



Amperes. 



O.G.S. 



C.G.S. 



O.G.S. 



s/Sng 



Obs. 











Dale. 











181* 



11390 



892 



725 



71-8 



-0-7 



0-13 



558 



17550 



1353 



111-8 



107-3 



-4-5 



0-37 



1615 



19750 



1444 



125-8 



121-3 



-4-5 



0-91 



3470 



22510 



1516 



143-4 



1390 



-44 



1-31 



5050 



24000 



1508 



152-9 



148-7 



-4-2 



2-6 



8670 



27950 



1535 



178-0 



1746 



-34 



3-8 



10750 



30290 



1556 



193-0 



187-6 



-54 



5-7 



12830 



31950 



1522 



203-5 



201-1 



-24 



8*0 



14220 



32860 



1484 



209 3 



2073 



-20 



9-9 



14860 



33470 



1481 



2131 



211-3 



-1-8 



14-9 



15970 



35380 



1545 



225-4 



221-9 



-35 



250 



17830 



36110 



1456 



230-0 



230-2 



4-0-2 



* Due to residual magnetism in the pole-pieces. 



Tables III. and IV. contain the values of the exciting 

 current, H, B, I, B/ */ Sirg, of the quantity 



G V p+ £HJ>' 



and, lastly, of the difference 



a- 



B 



VSirg 

 in iron and steel. 



Table II. contains the results of my former experiments 

 (I. c. p. 265), which are here reproduced in order to show the 

 complete range experimented over. 



The results are also exhibited graphically in fig. 2, in which 

 the points +, 0, show the values of G as a function 

 of B in iron and steel respectively, while the straight line 

 represents the function B/ \/Sirg. 



The points # are taken from the former experiments, 

 and represent the square root of the tractive force per sq. 



centim., which in that case was theoretically equal to — 



\/Sirg 



All the observed points lie near the straight line ; the 



greatest difference is about 3 per cent. Most of the points 



lie under the line ; this is probably due to the spreading 



action of the gap in the isthmus, which diminishes the tractive 



