ad to think of large birds. He thought of cranes.

He consulted ornithologists, and learned that the configuration of
parallel lines agrees with the flight-formation of cranes. This was in
1880: anybody now living in New York City, for instance, would tell him
that also it is a familiar formation of aeroplanes. But, because of data
of focus and subtended angles, these beings or objects must have been
high.

Sig. Ricco argues that condors have been known to fly three or four
miles high, and that heights reached by other birds have been estimated
at two or three miles. He says that cranes have been known to fly so
high that they have been lost to view.

Our own acceptance, in conventional terms, is that there is not a bird
of this earth that would not freeze to death at a height of more than
four miles: that if condors fly three or four miles high, they are birds
that are especially adapted to such altitudes.

Sig. Ricco's estimate is that these objects or beings or cranes must
have been at least five and a half miles high.

17

The vast dark thing that looked like a poised crow of unholy dimensions.
Assuming that I shall ever have any readers, let him, or both of them,
if I shall ever have such popularity as that, note how dim that bold
black datum is at the distance of only two chapters.

The question:

Was it a thing or the shadow of a thing?

Acceptance either way calls not for mere revision but revolution in the
science of astronomy. But the dimness of the datum of only two chapters
ago. The carved stone disk of Tarbes, and the rain that fell every
afternoon for twenty--if I haven't forgotten, myself, whether it was
twenty-three or twenty-five days!--upon one small area. We are all
Thomsons, with brains that have smooth and slippery, though corrugated,
surfaces--or that all intellection is associative--or that we remember
that which correlates with a dominant--and a few chapters go by, and
there's scarcely an impression that hasn't slid off our smooth and
slippery brains, of Leverrier and the "planet Vulcan." There are two
ways by which irreconcilables can be remembered--if they can be
correlated in a system more nearly real than the system that rejects
them--and by repetition and repetition and repetition.

Vast black thing like a crow poised over the moon.

The datum is so important to us, because it enforces, in another field,
our acceptance that dark bodies of planetary size traverse this sol