ON FLUORESCENCE PRODUCED BY THE AURORA.
To John Tyndall, Esq. | Observatory, Armagh, | March 24, 1858.
MY DEAR SIR,
I DO not know whether the fact mentioned in the enclosed2 has been noticed before. If not, perhaps you may think it worth inserting in the Philosophical Magazine.
Yours ever, | T. R. ROBINSON.
_________________
On the 14th instant an aurora was visible here of more than the average brightness. At 11 P.M it showed an arch extending from W. to N.E. by E., which emitted a few yellow streamers; and the sky above it was covered with diffused light, over which brighter portions flickered like waves, extending several degrees beyond the zenith.3 I availed myself of the opportunity to try whether this light was rich in those highly refrangible4 rays which produce fluorescence, and which are so abundant in the light of electric discharges; and I found it to be so. A drop of disulphate of quinine on a porcelain tablet seemed like a luminous patch on a faint ground; and crystals of platinocyanide of potassium were so bright, that the label on the tube which contained them (and which by lamplight could not be distinguished from the salt at a little distance) seemed almost black by contrast.
These effects were so strong in relation to the actual intensity of the light, that they appear to afford an additional evidence of the electric origin of this phænomenon, and as such I hope they may interest some of your readers.
Phil. Mag., 15 (1858), pp. 326–7.
Thomas Romney Robinson: Thomas Romney Robinson (1793–1882), an Irish astronomer, physicist, and director of the Armagh Observatory from 1823 until his death (ODNB).
The enclosed: personal observations of Thomas Robinson made at Armagh observatory on 14 March 1858.
zenith: see letter 1415, n. 14.
refrangible: see letter 1481, n. 4.
Please cite as “Tyndall1501,” in Ɛpsilon: The John Tyndall Collection accessed on