Maximum Magnetism of Iron, Steel, etc. 417 
nickel, and cobalt; neither has the form of the function by 
which these quantities are connected with the degree of mag- 
netization been attempted, except so far as we may consider 
the erroneous formula of Miiller, above referred to, as such an 
attempt. 
In a preliminary experiment to determine on the mode of ex- 
periment to be adopted, it was shown that the distribution of 
magnetization in an electromagnet varied with the strength of 
the exciting current, so that no arrangement to measure the 
magnetization of the bar which is based on the deflection of a 
compass needle can give correct results. This has been theo- 
retically anticipated by Sir W. Thomson.t 
I believe mine are the first experiments hitherto made on 
this subject in which the results are expressed and the reason- 
ing carried out in the language of Faraday’s theory of lines of 
magnetic force. That my choice is a proper one and my results 
correct needs no further proof than that given in Prof. J. Clerk 
Maxwell's “ Treatise on Electricity and Magnetism,” where this 
theory is thoroughly worked out and shown to give exactly the 
same results as the older theories, where the action is assumed 
to take place at a distance without intervening matter. I believe 
there are great things in store for this theory, and its excellent 
Working qualities are shown in the method of measuring mag- 
hetism m absolute measure adopted, for which I claim that it is 
the most simple and accurate of any yet devised, and which was 
— to me while thinking of the matter according to this 
The absolute units to which I have reduced my results are 
those in which the meter and second, are the funda- 
’ 
meter of a unit field measured perpendicular to their direction. 
1 working out the theory of the operation, at first I used an 
uation which I obtained some time ago for the distribution 
i agnetism on a bar or ring magnet, but as I cannot here go 
th ty With the process of getting the equations, I will give 
*tollowing method. If n is the number of coils per meter 
the rt include here the theoretical formule of Weber and Maxwell, as they 
xperiment. 
Ait Jong Hlectrostatics and Magnetism, p. 512. 
Sia SoL—Taran Sunres, Vou. VI, No. 36.—Dzc., 1873, 
