ay also mention the extremely valuable series of
instantaneous photographs of living bacteria, blood-parasites and
infusoria produced by MM. Pathe, and the series of fishes and various
invertebrates (including the curious caterpillar-like Peripatus) taken
by Mr. Martin Duncan.

The representation of the moon in pictures of the ordinary size (some
three feet long by two in height) is a case in which the artist
habitually--one may almost say invariably--departs greatly from
scientific truth, and it is a question as to whether he is justified
in what he does. Take first the case of the low-lying moon near the
horizon as contrasted with the high moon. Everyone knows that the moon
(and the sun[4] also) appears to be much bigger when it is low than
when it is high. Everyone who has not looked into the matter closely
is prepared to maintain that the luminous disc in the sky--whether of
moon or of sun--not merely seems to, but actually does, occupy a
bigger space when it is low down near the horizon than when it is high
up, more nearly overhead. Of course, no one nowadays imagines that the
moon or the sun swells as it sinks or diminishes in volume as it
rises. Those who think about it at all, say that the greater length of
atmosphere through which one sees the low sun or moon, as compared
with the high, magnifies the disc as a lens might do. This, however,
is not the case. If we take a photograph of the moon when low and
another with the same instrument and the same focus when it is high,
we find that the celestial disc produces on the plate (as it does on
our eyes) a picture-disc of practically the same size in both
positions. In fact, the high moon or sun produces a picture-disc of a
little larger size than the low moon or sun. I have here reproduced
(Pl. IV) a photograph, published by M. Flammarion, in which the moon
has been allowed to print itself on a photographic plate exposed
during the time the moon was rising, and it is seen that the track of
the moon has not diminished in width as it rose higher and higher. No
one will readily believe this, yet it is a demonstrable fact.
Astronomers have made accurate measurements which show that there is
no diminution of the disc under these circumstances, but a slight
increase--since the moon is a very little nearer to us when overhead
than when we see it across the horizon.

[Illustration: Plate IV.--The track of the rising moon registered by
continuous exposure of a photographi