The enquirer. [volume] (Richmond, Va.) 1804-1815, 1811-05-10

ternaiely to the North, East, South, & West the
following phenomena are observed There will
be always certain portion OF light reflected by
the second plate but this quantity will be much
less when the faces of the plate, are turned to
wards the North aud South than when they are
turned towards the East and West. In the first
vertical ray appearances quite opposite were OBJ
served the minimum OF reflected light took
place when the second plate was turned towards
the East and West. Thus in abstracting from
the second ray the quantity flight which acts
rs an ordinary ray and which is reflected equal
iy IN the two cases, we perceive that this ray
contains another portion of light which is polar
ised exactly in contrary manner to that Of the
vertical ray reflected by the first plate. en-
ploy in this experiment silvercd mirror only to
throw the two rays parallel and similar SO as to
render the experiment more evident. The
non OF metallic surfaces being extremely weak
relatively to the polarization Of the direct ray we
mag neglect their influence"
" This phenomenon finally is reduced TO this.
When ray OF light falls upon plate of glass
forming with it an angle of incidence of35o, 25,
all the light which it reflects is polarsed i'm one
direction. The light which passes through the
glass is composed LIST of portion OF polarised
hight IN contrary manner to that which lras
been reflected and proportional to this quantity,
I'd Of another portion not modified and which
preserves the characters of the direct light
These polarised rays have precisely all the pro-
perties OF those which have been modified by
CRYSTALS which cause double refraction, so that
what have observed of these may also be APP
piled to them"
which may be deduced from the experiments
which l have mentioned, and which may be ad-
ded TO those which have already published on
this subject"
Whenever by any method polarsed ray is
produced, we necessarily obtain second ray
l IL, Il r..
| these rays follow different directions Light
| cannot receive this modification in one sense
without proportional part of it being affected in
contrary manner"
" The curious observations which M. Arago
has reported lately to the society would seem al
first sight TO be exception to this general rule
He has observed that colored rings by transmits
sion presented the phenomenon of poIarisat.
on and that in this case those with narrowest
surfaces appeared to be polarised in the same
manner as reflected light but on rcfec citing on
the causes OF this phenomenon, have perceiv-
ed that 1T Is not an exception to the general
rule"
- All bodies opaque or transparent have the
| effect OF polarising light under every angle al.
though in each body This phenomenon observes a
maximum under certain angle. We may then
| affirm IN genral that all light which has expert
enced the action of body by reflection or by re-
fraction, contains polarised rays whose poles
are determined relatively to the plane of refec-
| ton or refraction. This light has properties
| and qualities which that has not which pro
ceeds TO us Immediately from luminous boz
dies"
These are the principal facts and observations
| contained in The interesting memoir of M. Ma
lus. In the Monireur of the 18th March, there
is an essay on the same subject by NJ. Blot, but
as his experiments agree with those of M. Malus
and the details into which he enters, although
ingenious are not so interesting, their pubhcati.
on in your paper might net be deemed of much
Importance Il purpose to repeat in few days
the experiments of Malus and then shall be
better enabled to form an opinion on the sub
ject.
+. W.