156 Miscellaneous Intelligence. 
m not aware that those who have observed traces of polarization in 
the light of comets have noted the direction of the plane in which it has 
been polarized; nevertheless without some such observation we cannot 
discover its cause. If the light be polarized in a plane passing through 
the sun, the comet, and the eye, we must infer that it is polarized by the 
reflexion of the light coming from the sa if it be polarized in an oppo- 
site plane, the polarization be due to the refraction of the atmos- 
PRE or - the fact of one or more of the lenses Ses pinched in their 
ings of the object-glasses and eye-piece should be reduced to a central 
band, which would stuinats the light polarized in an opposite plane, and 
leave that which is polarized in a plane perpendicular to the direction. 
By turning the telescope or the onan, the direction of the polarization 
would be changed. 
If the polarization be produced by a defect in the annealing of the 
_ glass of which the lenses are made, as appears to be the case in one 
of Amici’s telescopes mentioned by M. Govi, the existence of this im- 
pete will be rendered evident by exposing the lenses to polarized 
If the  apoaiane agen observed be due to the reflexion of the rays of the 
sun by the comet or its envelops, small stars will be seen more distinctly 
ren it when the polarized light is extinguished by the application of 
a Nicol 
Whilst 'é was s investigating the erie of the atmosphere, I ob- 
served the remarkable fact, that when n objects situated far off m the open 
rendered indistinet by fogs or mists may, it appears to me, receive im- 
x saa eee in pri and naval operations.— Comptes 
segs a ane 9, p. 
alee Guide to the Furnaces, Forges and Rolling 
Mili ©, the United States, with discussion of iron as a chemical GR 
a ‘done a service which will be highly — iated 
by all who know the national importance of the iron industry, as * 
ke those whose researches lead them to seek in a compendious se ie rm all 
poemation on subjects connected with iron, to find which they have 
hitherto been forced to search through a wide of isolated authori- 
ties, Being a good geologist, familiar with the geology of Pennsylvania 
