Leonard Horner touched briefly on the topic of airborne dust during his presidential address to the Geological Society of London in 1847:
'You may probably recollect having read, in the newspapers of the autumn of 1845, an account of a quantity of dust having fallen from the atmosphere on the Orkney Islands; it was also said to have fallen to the thickness of an inch on ships in that part of the North Sea. It was supposed to indicate a volcanic eruption of ashes in Iceland; and the conjecture was proved to be correct; for, on the 2nd of September of that year, the great volcanic mountain of Hecla, after a repose of nearly 80 years , again burst forth. On the same day, a quantity of dust fell on a Danish ship in lat.61N., and longitude 7 58W. of Greenwich. It blew at the time strong from the NW by W. From this point Hecla is 533 miles distant...
In the Proceedings of the Royal Academy of Berlin for December 1845, there is an account of a paper read by Professor Ehrenberg, containing the result of a microscopic examination of the dust that fell on the Danish vessel; and in the Proceedings for May last there is a supplement to that paper, describing his examination of some ashes that had been erupted from Hecla on the day above-mentioned. Translations of these notices are given in the last number of the Quarterly Journal of this Society. In these notices, Professor Ehrenberg identifies the dust that fell on the ship with the ashes erupted from Hecla, and they afford another instance of that very remarkable fact, previously made known to us by the same philosopher, viz. the presence of the siliceous shells of infusoria in ashes ejected from volcanos in many different countries. He found thirty-seven different species of these minute organisms, not one of them decidedly new, and all of them peculiar to fresh water. Fifteen of them are living forms known to exist at present in Iceland.'
'You may probably recollect having read, in the newspapers of the autumn of 1845, an account of a quantity of dust having fallen from the atmosphere on the Orkney Islands; it was also said to have fallen to the thickness of an inch on ships in that part of the North Sea. It was supposed to indicate a volcanic eruption of ashes in Iceland; and the conjecture was proved to be correct; for, on the 2nd of September of that year, the great volcanic mountain of Hecla, after a repose of nearly 80 years , again burst forth. On the same day, a quantity of dust fell on a Danish ship in lat.61N., and longitude 7 58W. of Greenwich. It blew at the time strong from the NW by W. From this point Hecla is 533 miles distant...
In the Proceedings of the Royal Academy of Berlin for December 1845, there is an account of a paper read by Professor Ehrenberg, containing the result of a microscopic examination of the dust that fell on the Danish vessel; and in the Proceedings for May last there is a supplement to that paper, describing his examination of some ashes that had been erupted from Hecla on the day above-mentioned. Translations of these notices are given in the last number of the Quarterly Journal of this Society. In these notices, Professor Ehrenberg identifies the dust that fell on the ship with the ashes erupted from Hecla, and they afford another instance of that very remarkable fact, previously made known to us by the same philosopher, viz. the presence of the siliceous shells of infusoria in ashes ejected from volcanos in many different countries. He found thirty-seven different species of these minute organisms, not one of them decidedly new, and all of them peculiar to fresh water. Fifteen of them are living forms known to exist at present in Iceland.'
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