MAGNETIC SHIELDING IN HOLLOW IRON CYLINDERS. 



671 



Table I. — Magnetic, Induction. — Permeability. — Theoretical Shielding Ratio. (See Fig. IV.) 









Shi elw 



A. 

 oju B-H 















Shield 



B. 





Increments 

 from Zero. 



Derived fr 



curves- 



. fig- iv 





Increments 

 from Zero. 



Derived from the B-H curves, fig. IV. 



H, 



B 



H e 



B 



B 

 H 



(.'/) 



dB 

 dH 



9 



H, 



B 



380 



H f 

 1 



B 



B 



H 



(?) 



dB 



dH 



((</)) 



•44 



295 



•6 



500 



800 



7-5 



1000 



•94 



400 



400 1 5 



830 



9-3 



'75 



715 



•75 



750 



1000 



90 



2000 



17 



1 4:. 



832 



2 



1,750 



875 



9-8 



1800 



19 



•97 



1,305 



1 



1,300 



130(1 



11-4 



3000 



25 



2-06 



1,840 



2-5 



2,700 



1080 



11-8 



2000 



21 



17 



4,050 



13 



3, COO 



2300 



19-4 



4500 



37 



2-33 



2,360 



3 



3,700 



1-233 



13 3 



1660 



17-7 



3 



7,200 



2 



5,225 



2625 



220 



3000 



25 



•2-77 



3,296 



4 



5,400 



1375 



14-7 



1330 



143 



4-15 



8.90O 



3 



7,200 



2400 



20-2 







308 



3,920 



5 



6,700 



1340 



14-4 



1150 



12-5 



6-6 



11,000 



4 



8,700 



2175 



18-4 



1250 



11 



3-80 



5,064 



6 



7,600 



1260 



136 



850 



9-5 



93 



12,600 



6 



10,600 



1770 



15-2 



750 



7-0 



4-35 



5,860 



7 



8,400 



1200 



13-0 



700 



80 



13 2 



13,600 



9 



12,400 



1400 



12 2 



430 



4-4 



5-73 



7,350 



8 



9,000 



1125 



12-2 



600 



70 



15 7 



14,100 



12 



13,300 



1100 



9-8 



250 



30 



7-42 



8,600 



10 



10,000 



1000 



11-0 



470 



5-7 



18-3 



14,300 



15 



14,000 



933 



8-5 



160 



2-3 



94 



9,745 



15 



11,800 



787 



8-9 



280 



38 



23 



14,650 



20 



14,500 



725 



6-8 



77 



1-6 



15"2 



11,900 



20 



13,000 



650 



7-5 



200 



3 



49-9 



15,700 



25 



14,750 



588 



5-7 







21-2 



13,300 



25 



13,900 



556 



60 











30 



15,000 



500 



5 



50 



14 



29-7 



14,50d 



30 



14,500 



483 



5 8 



110 



21 







35 



15,200 



434 



4-5 







36 3 



15,150 



35 



15,000 



42 ^ 



5-3 







Table II. — Hysteresis Loop. — Theoretical 

 Shielding Ratio. (See Fig. vil.) 



Table III. — Magnetic Induction. — Theoretical 

 Shielding Ratio. (See Fig. V.) 



Shiki.d A. 



Shield B. 



Cyclic. 



From B-H 

 curve of 



fig. VII. 



Cyclic. 



From B-H 

 curve of 

 fig. vil. 



H, 



B 



dB 

 dH 



2 



5 

 10-6 

 14-3 



33 



57 



97 



73 



22-3 



14-3 



'I 



H, 



B 



rfB 

 dH 



((.'/)) 



'. 5 

 1 2-24 

 •66 



I -° 



- -38 



'- -66 



- -83 

 -1-2 

 -1-37 

 -2-24 

 -2-9-2 

 -4-03 

 -5 



9600 

 9020 

 7650 

 6920 

 6000 

 5200 

 4430 



-1520 

 -5700 

 -7080 

 -8600 

 -9600 



125 



500 

 200 

 836 



000 



7,000 

 12,000 

 9,000 

 2,666 

 1,666 

 1,250 

 1,000 



9-4 

 5-72 

 3-0 

 1-7 

 

 -1-04 

 -T7 

 -2-0 

 -2-3 

 -2-54 

 -3-0 

 -4-23 

 -5-85 

 -8-15 

 - 9-4 



9750 

 9060 

 8300 

 7560 

 6180 

 4880 

 3420 

 1960 



- 960 

 -2800 

 -5450 

 -7400 

 -9200 

 -9750 



180 



250 



470 



666 



1000 



1600 



3000 



5500 



6000 



5000 



3000 



1500 



1000 



600 



500 



2-8 

 3-5 

 5-7 

 77 



11 



17 



31 



56 



61 



51 



31 



16 



11 

 7 

 6 





Shield A. 





Shield B. 



B determined 



by reversals 



ofH,. 



Derived from 



B determined 



Derived 



fig- 



IV. 



by reversals 

 of H,. 



from fig. iv. 



H, 



B 



It/) 



((.'/)) 



H, 



B 



(g) 



((?)) 



9-5 



1.225 



11 



•22 



7-4 



720 



G 



12-5 



17-6 



•2.2S0 



17 



37 



15-9 



1,600 



9 



18 



, 26-0 



3,420 



21 



33 



27 



2,800 



12 



21 



30 



3,880 



22-:; 



31 



39 



4,040 



14 



16-9 



1 41 



5,380 



21-6 



24 



51-5 



5,350 



14-7 



14-2 



53-3 



6,930 



20-3 



153 



65 



6,700 



14-3 12 



64-6 



8,230 



19 



12 



75-8 



7,700 



13-5 9*6 



76 



9,540 



17 



9 



90 



9,120 



12 7 



90 



11,220 



14-1 



6-1 



102 



10,250 



11 



5-3 



102 



12.600 



12-1 



4-1 



116 



11,500 



9 



4-2 



117 



14,100 



8 



2 



130 



12,600 



8 



3-1 



133 



15,250 



4-1 



1-2 







1 





TRANS. ROY. SOC. EDIN , VOL. XL. PART III. (NO. 2G). 



5 F 



