its body may be less capable of reflecting light than others; and when
the splendour of its primary and our inconvenient station for watching
it are considered, it must be conceded that, however slight the hope may
be, search ought not to be relinquished.'

Setting aside Scheuten's asserted recognition of a dark body near Venus
during the transit of 1761, Venus has always appeared without any
attendant when in transit. As no one else claimed to have seen what
Scheuten saw in 1761, though the transit was observed by hundreds, of
whom many used far finer telescopes than he, we must consider that he
allowed his imagination to deceive him. During the transit of 1769, and
again on December 8-9, 1874, Venus certainly had no companion during her
transit.

What, then, was it that Cassini, Short, Montaigne, and the rest supposed
they saw? The idea has been thrown out by Mr. Webb that mirage caused
the illusion. But he appears to have overlooked the fact that though an
image of Venus formed by mirage would be fainter than the planet, it
would not be smaller. It might, according to the circumstances, be above
Venus or below, or even somewhat towards either side, and it might be
either a direct or an inverted image, but it could not possibly be a
diminished image.

Single observations like Cassini's or Short's might be explained as
subjective phenomena, but this explanation will not avail in the case of
the Copenhagen observations.

I reject, as every student of astronomy will reject, the idea of wilful
deception. Occasionally an observer may pretend to see what he has not
seen, though I believe this very seldom happens. But even if Cassini and
the rest had been notoriously untrustworthy persons instead of being
some of them distinguished for the care and accuracy with which their
observations were made and recorded, these occasional views of a phantom
satellite are by no means such observations as they would have invented.
No distinction was to be gained by observations which could not be
confirmed by astronomers possessing more powerful telescopes. Cassini,
for example, knew well that nothing but his well-earned reputation could
have saved him from suspicion or ridicule when he announced that he had
seen Venus attended by a satellite.

It seems to me probable that the false satellite was an optical illusion
brought about in a different way from those referred to by Hell and
Brewster, though among the various circumstances w