Royal Institution | 29 Jany 1853
My dear Sir
I have only at this moment been able to read your letter,1 having laid all I could aside that I might write some simple plain notes of last F. evening:2 and now that I take it up, I cannot venture to judge of your experiments3 or draw conclusions from them not having seen the experiments or the apparatus employed. I never can decide upon a result until I have seen the experiment it depends upon made and then never until I have considered repeated & varied the experiment Pluckers conclusion4 is one that I do not know of my own knowledge to be correct I mean the varying rate of change of the Paramagnetic5 & diamagnetic form6 of force though I have seen many experiments.7 I know that some of the forces of his experiments are truly stated and think he may be right, but would not vouch for it or give it as my own decided opinion. There is no end to the cases in which I think it safest not to come to a conclusion least it should be erroneous
Ever Truly Yours | M. Faraday
Dr. J. Tyndall | &c &c &c
APS Mss.Ms.Coll.200
Faraday Correspondence, 4:2632
your letter: see letter 0708.
Last F. evening: refers to Faraday’s lecture at the RI on Friday, 21 January (see letter 0708 n. 4).
your experiments: Tyndall had previously written to Faraday regarding experiments conducted while in Berlin in which he noted a difference in intensity of repulsion of iron and salt of iron when immersed in water (Journal, 21 January, JT/2/13b/597).
Pluckers conclusion: this may likely refer to Plücker’s conclusion that the magnetic and diamagnetic forces changed differently with respect to distance from the poles.
Paramagnetic: the form of induced magnetism whereby materials, usually elements, are attracted by an externally applied magnetic field and form internal magnetic fields in the direction of the applied magnetic field.
diamagnetic form: the form of induced magnetism whereby materials are repelled by an externally applied magnetic field and form internal magnetic fields in the opposite direction of the applied magnetic field.
I mean … many experiments: diamagnetism is ‘an extremely weak and complex property of matter, easily overpowered by contamination with minute amounts of paramagnetic materials and dependent on the nature of the magnetic field in relation to the size and shape of substances’ (Jackson, ‘John Tyndall and Diamagnetism’, p. 438). Since 1847, there had been ongoing experiments done by the likes of Faraday, Plücker, Wilhelm Weber, and Tyndall seeking to understand the diamagnetic properties of substances (Jackson, ‘Tyndall and Diamagnetism’).
Please cite as “Tyndall0710,” in Ɛpsilon: The John Tyndall Collection accessed on