J. C. Maxwell’s, ‘Dynamical theory of the electromagnetic field’

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                                (116) The dimensions of the coil used by the Committee of the British Association 
in their experiments at Kings College in 1864 were as follows 
Mean radius = a = .158194 metre 
depth of each coil = b = .01608 
breadth of each coil = C = .01841 
distance between the coils = .02010 
number of windings n = 313 
diameter of wire = .00126 
The value of L derived from the first term of the expression 
is 437440 meters 
The correction depending on the radius not being infinitely great compared 
with the section of the coil as <s>derive<\s> found from the second term is 
— 7345 meters 
The correction depending on the diameter of the wire is per unit of length 
+ .44997 Correction for 8 neighbouring wires + .0236 
for 16 wires next to these + .0008 Correction for variation of current <s>from cent<\s> in different parts of section - .2500 
Total correction per unit of length .22<s>3<\s>437 
Length 311.236 meters 
Sum of corrections of this kind 70 meters 
Final value of L by calculation 430165 meters 
This value of L was employed in reducing the observations, according 
to the method explained in the Report of the Committee* <s> The results 
of 16 experiments in which this <\s> The correction depending on L varies 
as the square of the velocity. The results of 16 experiments to which 
this correction had been applied <s>more compared<\s> and in which the 
velocity varied from 100 revolutions in 17 seconds to 100 in 77 seconds 
were compared by the method of least squares to determine what further 
correction depending on the square of the velocity should be applied 
to make the outstanding errors a minimum 

* Brit Ass. Report 1863 p. 169
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James Clerk Maxwell
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Cite as

J. C. Maxwell’s, ‘Dynamical theory of the electromagnetic field’, 1864. From The Royal Society, PT/72/7



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