t/o Jefferson Physical Laboratory. 



465 



For <>ur piers / = 30 l ' m , and ^=28 om . 



The value of F for different values of a? computed from the 

 above expression is given in the following table: 





F. 



cm 



o-ooo G 



5 



0*570 G 



10 



l-iu a 



15 



1-620 G 



20 



2-080 <7 



25 



2-446 tf 



■''it 



F. 



30 cm 



2*698 G 



35 



2-833 G 



40 



2-856 G 



45 



2-796 G 



50 



2-082 ff 



60 



2*390 O" 



Plotting the coefficients of a we obtain a curve very similar 

 to that of pier 5, fig. 6, showing that the assumption of uni- 

 form distribution agrees well w T ith the observed values. 



The maximum observed value is about -005 H = -00085 abso- 

 lute units and corresponds to the computed value 2*8 o ; hence 

 <r='0003 and the total amount of free magnetism on the sur- 

 face of the piers, 3600 scj. cm., is 1*08 C. G-. S. units. 



Pier 5. 



Distance 







Distance East of Center (inches). 







North of 



















Center, 

 (inches.) 



-14 



-10 



-6 



-2 



+ 2 



+ 6 



+ 10 



+ 14 



+ 18 



-0012 



— 0023 



—0023 



— 0026 



— 0026 



— 0021 



-0020 



-0016 



+ 14 



-0018 



— 0029 



-0033 



— 0038 



-0037 



— 0032 



— 0031 



-0019 



+ 10 



—0016 



— 0026 



— 0034 



-0038 



— 0038 



— 0034 



— 0029 



— 0024 



+ 6 ' 



-0012 



— 0022 



-0028 



-0026 



-0028 



— 0024 



-0021 



— 0013 



+ 2 



-0004 



-0008 



-0009 



— 0007 



— 0011 



-0007 



— 0010 



-0009 



- 2 



+ 0010 



+ 0008 



+ 0011 



+ 0012 



+ 0007 



+ 0006 



+ 0002 



-0001 



- 6 



+ 0025 



+ 0025 



+ 0031 



+ 0033 



+ 0029 



+ 0025 



+ 0017 



+ 0011 



-10 



+ 0038 



+ 0042 



+ 0049 



+ 0052 



+ 0051 



+ 0045 



+ 0037 



+ 0022 



— 14 



+ 0042 



+ 0048 



+ 0055 



+ 0057 



+ 0059 



+ 0052 



+ 0046 



+ 0026 



-18 



+ 0036 



+ 0041 



+ 0047 



+ 0048 



+ 0049 



+ 0046 



+ 0043 



+ 0027 



Pier 4. 





Distance East of Center (inches). 



North of 















Center. 



(inches.) 



-15 



-9 



-3 



+ 3 



+ 9 



+ 15 



+ 18 



— •00005 



— 00040 



+ •00010 



— •00005 



+ •00020 



+ 00025 



12 



— '00025 



-00020 



+ •00030 



+ •00065 



+ •00030 



+ 00020 



6 



— -00025 



00000 



+ •00040 



+ •00040 



— •00020 



+ 00010 







+ •00010 



+ 00020 



+ •00020 



— •00020 



— •00090 



—00020 



- 6 



+00080 



+ 00075 



+ •00060 



+ •00050 



+ •00050 



+ 00040 



12 



+ •00160 



+ 00170 



+ •00160 



+ •00160 



+ •00170 



+ 00130 



18 



+ •00170 



+ 00190 



+ •00195 



+ •00190 



+ •00155 



+ 00140 



