William Whewell to Faraday   12 August 1850

Kreuznach, | Rhenish Prussia

My dear Sir

I am always glad to hear of your wanting new words¹, because the want shows that you are pursuing new thoughts, and your new thoughts are worth something: but I always feel also how difficult it is for one who has not pursued the train of thought to suggest the right word. There are so many relations involved in a new discovery and the word ought not glaringly to violate any of them. The purists would certainly object to the opposition or coordination of terro-magnetic and diamagnetic, not only on account of the want of symmetry in the relation of terro and dia, but also because the one is Latin and the other Greek. But these objections, being merely relative to the form of the words would not be fatal, especially if the new word were considered as temporary only to be superseded by a better when the relation of the phenomena are more clearly seen. But a more serious objection to terromagnetic seems to me to be that diamagnetic bodies have also a relation to the earth as well as the other class; namely a tendency to place their length transverse to the lines of terrestrial magnetic force. Hence it would appear that the two classes of magnetic bodies are those which place their length parallel or according to the terrestrial magnetic lines, and those which place their length transverse to such lines. Keeping the preposition dia for the latter then the preposition para or ana might be used for the former; perhaps para would be best as the word parallel, in which it is involved, would be a mechanical memory for it. Thus we should have this distinction

If you like anamagnetic better than paramagnetic, as meaning magnetic according to our standard, terrestrial magnetism, I see no objection. I had at one time thought of ortho magnetic and diamagnetic, directly magnetic and diametrally [sic] magnetic, but here the symmetry is not so complete as with two prepositions.

In considering whether I quite understand the present state of the subject, I have asked myself what would be the effect of a planet made up of bits of bismuth, phosphor &c, of which the general mass had their lengths parallel to a certain axis of the planet. I suppose all paramagnetic bodies would arrange themselves transverse to its meridian, and all diamagnetic bodies in its meridian. Am I right?

I rejoice to hear that you have new views of discovery opening to you. I always rejoice to hail the light of such when they dawn upon you.

I have been at the meeting of Swiss naturalists at Aarau, where I met Schönbein who talked much of you, and told me you were going to explain his views of ozone².

I shall be in London in a few days and shall perhaps try to see you when I am there. Letters sent to Cambridge always find me.

Believe me, my dear Sir, yours most truly | W. Whewell

Address: England | Dr Faraday | Royal Institution | Albemarle Street | London

Postmark: 12 August 1850