Julius Plücker to Faraday   14 March 1857

My dear Sir!

I take liberty to send to you the announced paper on the magnetic induction of crystals¹ - not without some hesitation. Is it not rather strange that a Professor of Bonn presents so large a paper to the Royal Society?

Not being acquainted with the “coutumes” of this Society, I have written a few word to the foreign Secretary². I pray you, Sir, to send to him the paper with the letter, if this be the way. In addressing it to you, I principally wished to offer to you the occasion to look previously at the paper and especially to the note (p.6) concerning Prof Tyndall³. I think there is no offense given to him.

Tis now exactly ten years ago, I made the first observation on the new way opened by yourselves. After many disappointments I finally succeeded - I think so at least - to give a theory of all the various phenomena and to support this theory, in verifying experimentally the numerical values derived from it. Let me refer here only to the experiments with a sphere of formicate of copper. You may directly find after some trials, what I have called the magnetic axis of this salt, a crystal when suspended along one of these axes (including an angle of 50°,) not being acted upon in an extraordinary way. You may obtain them by counting the oscillations of the crystalline sphere, when successively suspended along any two determined directions. You may get them by observing its position, when suspended along any known direction and hence deduce its position, when suspended along any other direction (p.53-57)⁴. You may lastly determine them by a curious method, wich I applied to crystallised bismuth - to get exact number my sphere of formicate of copper wanted a different torsion - wire (note p.65)⁵.

Excuse me, Sir, in giving to you so much trouble. I hope you are well. With all my heart | Yours | Plücker

Bonn, March.14. 1857.

PS. If there be any inconvenient to lay my paper before the Royal Society, I beg you to put it aside and to burn the letter to the foreign Secretary⁶.