Oldal 102 [102]
56 LIGHT AND WATER
excellent photographs of fishing smacks by Mr. C. E.
Wanless show some beautiful and curious effects of
foreground reflexions, and are of more value than
many words in illustrating the play of the water, or
as suggestions for the drawing of ripples. (Plates
XXVI-XXXII, XXXVII.)
NOTE ON THE PERSPECTIVE OF ELONGATED
KEFLEXIONS.
On page 36 we saw how the streak of light which appears
in rippled water as the reflexion of a luminous point, such
as a lamp, is formed by the light catching the surface of the
water at different points which, neglecting the irregularities
of the surface, may be said to lie on a straight line on the
surface extending from a point vertically below the eye
to a point vertically below the lamp. For example, the
points A, B, C, D, E, F, etc. (Figs. 14 and 15) lie on sucha
line. If several lamps are seen reflected side by side, the
streaks of light on the surface of the water corresponding
to them will evidently zo¢ be parallel, radiating as they do
from the point below the eye. But these streaks of light
regarded as lines de/ow the surface have been shown (page
36) to appear as vertical—and therefore parallel—lines.
The question might therefore arise, should these streaks
of light de drawn as vertical lines, or as lines radiating from
the “Point of Station?” That the former is the correct an¬
swer is clear from a consideration of Fig. 14. Viewed from
QO, the perspective representations of the points a, 6, c, d, e,
etc. (z.e., their projections on to the picture plane), must lie
in the same vertical line with that of P, as shown in Fig. 15.
If there were a second luminous point alongside of P (Fig.
15) its images would in the same way arrange themselves
in the vertical line through that point, and so on for any
number of luminous points. Should further proof be required,
it is given by the law of perspective that the vanishing point