On the shape of derived shadows (166-174).
HOW A CAST SHADOW CAN NEVER BE OF
THE SAME SIZE AS THE BODY THATCASTS IT. Shadow is the absence of light, merely
the obstruction of theluminous rays by an opaque body. At the spot _B_ on
thesecond diagram he wrote _lume libero_ (diffused light).
Let _a_ be the
light, _b_ the eye, _c_ the object seen by the eyeand in the light. The shaded
images increase from _o g_ and end at 7 and 8. Shadow is the absence of light,
merely the obstruction of theluminous rays by an opaque body. Shadow isthe
means by which bodies display their form.
The cast shadow will be shortest when
the light is highest.
WHAT BODIES HAVE LIGHT UPON THEM WITHOUT LUSTRE? And _m
p_ will go into _h p_ as often as_d c_ into _o p_.
Derived shadow is that which
is disengaged from a body inshadow and pervades the air.
__The plan of a scheme
of arrangement suggested in No. Definition of the nature of shadows (119--122).
Derived shadow is that which is disengaged from a body inshadow and pervades
the air.
Butthis only happens when the light enters by a window. A compound
shadow is one which is somewhat illuminated by one ormore lights.
The edges of
the derived shadow are straight lines.
In the reproduction of this diagram
theletter _v_ at the outer right-hand end has been omitted. OF THE THREE KINDS
OF LIGHT THAT ILLUMINATE OPAQUE BODIES. OF THE DIMINUTION OF OBJECTS AT VARIOUS
DISTANCES.
Of the various kinds of light (126, 127).
They are always associated
andinseparable from all objects.
WHAT BODIES WILL DISPLAY LUSTRE BUT NOT LOOK
ILLUMINATED? A simple shadow is one where no light at all interferes with it.
Why is the shadow _e a b_ in the first grade of strength, _b c_ inthe second;
_c d_ in the third? It is inevitable that every shadow must have its centre in
aline with the centre of the light. Of the various kinds of light (126, 127).
Then again _a_ _b_ falls on the shaded bodyat _i_ _g_ and forms a pyramid _f_
_i_ _g_.
|