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PROGRESS OF MICROSCOPICAL SCIENCE. 
partly plain, partly connected together in the form of Y or T. The 
filaments are commonly full of cavities, or pierced in the direction of 
their length by hollow canals, whereby they are often light enough to 
be able to float on water. On being examined in polarized light, most 
of the grains of dust are found to be isotropic — that is, without action 
on the polarization plane of the light passing through them. Only 
exceptionally can there be discovered under the microscope doubly 
refracting crystalline particles, presumably of augite or felspar, and 
non-transparent black grains of magnetic iron-ore, that may be drawn 
out with the magnet. No traces of metallic particles could be dis- 
covered in the dust by trituration in an agate mortar and washing, 
nor did chemical reagents show the presence of cobalt or nickel." 
He gives the following explanation of its origin : " Under the micro- 
scope the Haga dust has in many respects a striking likeness to the 
finest dust from a so-called ' Bologna drop ' that has sprung asunder, 
that is, a drop of glass which has been cooled suddenly, and there- 
fore, from the most inconsiderable cause, for example, a scratch with 
a file on its surface, falls asunder to a fine powder. Here we have 
possibly a hint as to the formation of this dust. On the outbreak of 
the volcano, an immense quantity of superheated steam and strongly 
compressed gases has violently escaped out of the crater's lava-sea, 
and brought along with it masses of its glowing contents more or less 
finely divided. Naturally the particles of lava, which at first are in a 
molten state, not only solidify suddenly, but are also cooled to a very 
low temperature in the upper strata of the atmosphere, and thereby 
obtain the property of the ' Bologna drop,' of springing asunder, 
with the least concussion or shaking, to a fine dust." 
The Kentucky Meat Shower. — This strange phenomenon, which 
produced a large amount of scepticism on the part of some, has been 
now very thoroughly explained in the following letter of Dr. Mead 
Edwards, in a late number of the * Scientific American.' After 
describing the occurrence at some length, he then states the results 
of his examination of portions of the so-called shower which fell at 
Kentucky, and says : — " Being determined to follow the matter up, I 
wrote to Mr. Parker, and he very kindly sent me three specimens, two 
in the natural state as they fell, and one prepared and mounted for 
the microscope. The last named consists entirely of cartilage ; one of 
the others is likewise a mass of cartilage, while the remaining portion 
shows a few striated muscular fibres, along with what appears to be 
dense connective tissue, but in such a condition that its exact character 
cannot be well made out. I am promised further specimens and in- 
formation by Mr. Parker, who has been unsparing in his endeavours 
to elucidate the mystery; whilst he has been, at the same time, 
extremely liberal in the matter of distributing specimens. So much 
for the facts. Every specimen I have examined has proved to be of 
animal origin, showing that the Kentucky shower was a veritable 
' meat ' shower. As to whence it came I have no theory. Mr. Parker 
informs me that the favourite theory in the locality is, that it pro- 
ceeded from a flock of buzzards, who, as is their custom, seeing one 
of their companions disgorge himself, immediately followed suit. In 
