July 28. 55 | Observatory | Armagh
My dear Sir
I have read with much pleasure and improvement the Bakn Lecture2 which you were so kind [to send me.] Both in the sagacity of its reasoning and the elegance of its experiments it is well worthy of your fame. In one respect it will be very useful, that of forcing on the mind full conviction of the futility of the existing hypotheses3 which attempt to explain magnetic phænomena. On that point I feel quite adrift.
In one point only I think Paramagnetic and Diamagnetic forces seem to agree, in being lessened by an increase of temperature. Has any comparison been made of fluid and frozen mercury in the diamagnetic relation?
I hope to meet you at Glasgow next month.4
Yours ever | T. R. Robinson
J. Tyndall Esq M D5
RI MS JT/1/R/31
Robinson: Thomas Romney Robinson (1793–1882), an Irish astronomer and physicist, was the director of the Armagh Observatory and president of the Royal Irish Academy.
the Bakn Lecture: the Bakerian Lecture; see letter 1029, n. 1.
the existing hypotheses: In his Bakerian Lecture (pp. 14–15) Tyndall had addressed the hypotheses that Poisson and Ampère developed to explain the phenomenon of diamagnetism.
at Glasgow next month: at the forthcoming meeting of the BAAS.
M D: Robinson must have mistakenly thought that Tyndall was a doctor of medicine, whereas he had been awarded his PhD at the University of Marburg in 1850.
Please cite as “Tyndall1119,” in Ɛpsilon: The John Tyndall Collection accessed on