SCIENTIFIC SUMMARY 
ASTRONOMY. 
Meteoric Dust. — Mr. Ranyard has contributed to the “ Proceedings ” of the 
Royal Astronomical Society a very interesting paper on the presence of me- 
teoric dust in the atmosphere. Professor Andrews announced in 1852 that he 
had discovered particles of native iron in the basalt of the Giant’s Causeway, 
and suggested that they may have been derived from meteors which fell 
when the basalt was in a plastic condition. In 1867, Mr. Phipson, in a 
book on meteors, said : “ I have found that when a glass covered with pure 
glycerine is exposed to a strong wind, late in November, it receives a certain 
number of black angular particles , some three or four of which may be thus 
collected in the space of a couple of hours.” These can be dissolved in 
strong hydrochloric acid, and produce yellow chloride of non upon the glass 
plate.” He adds : “ Although I have made this experiment at various periods 
of the year, it is only in the winter months that the black particles giving, 
with hydrochloric acid, chloride of iron, have been met with.” Towards the 
end of 1871, Nordenskjold collected some apparently pure snow which fell 
in the neighbourhood of Stockholm during a heavy snowstorm, and on melt- 
ing a cubic metre of the snow he found that it left a black residue, from 
which he was able to extract with a magnet particles which, when rubbed 
in an agate mortar, exhibited metallic characters, and on being treated with 
acid proved to be iron. Nordenskjold also found particles of magnetic iron 
in snow which he collected from off the ice of Rantajerwi, a spot separated 
by a dense forest from the nearest houses at Evoia, in Finland. The Arctic 
Expedition of 1872 led to results still more striking, black granules contain- 
ing iron, phosphorus, cobalt, and probably nickel, being found in snow col- 
lected in spots very remote from human habitations. M. Tissandier has 
described the particles of solid matter found in deposits of dust on the 
towers of Notre Dame as resembling those which he was able to detach by 
friction from the surface of meteorites, and concludes “ that they are the 
solidified metallic rain detached from meteoric masses during their passage 
through the atmosphere.” Dr. Walter Flight published, in 1875, an impor- 
tant paper describing a kind of grey dust which he calls crgoconite, met 
with in holes in Polar ice, and forming a layer of grey powder at the bottom 
of the water filling the holes. He says : u The origin of cryoconite is highly 
enigmatical. That it is not a product of the weathering of the gneiss of 
the coast is shown by its inferior hardness, indicating the absence of quartz, 
