It is possible to-day, as it most certainly was in those traditional
days, to behold a complete circular Rainbow at Niagara; generally, only
when one is out in front of the falling waters, close to the spray,
near the level of the river in the Gorge; always with the Sun at one's
back--and the Sun must shine brightly, and the Mist must be plentiful.
It is possible to see a complete circular Rainbow anywhere, on land or
water, whenever one stands between the Sun and a sufficiently abundant
mist (standing close to the latter), and the Sun is near the horizon.
It is possible to see it, at some point at Niagara, often,--that is on
every bright day,--because that abundant curtain of mist is ever
present; and the Gorge, by reason of its great width and depth, affords
specially favorable opportunities.
This curious phenomenon is obtainable easily and regularly only in the
Gorge at the Goat Island end of the American Fall, from the rocks in
front of the Cave of the Winds (for the prevailing winds of the
locality are from the southwest, which bring the spray cloud into the
best relative position at this point), or from the deck of the
steamboat, at certain parts of the trip,--and from both only in the
afternoon.
It can sometimes be seen from Prospect Point, and from the Terrapin
Rocks--in the early morning, when the spray-cloud rises towards the
north.
It can also, sometimes (at the season when the Sun sets farthest to the
northward), be seen from the rocks out in front of the American Fall,
below Prospect Point.
This was the spot where the Aborigines would most easily have tested
the efficacy of the Legend; for their descent into the Gorge was made
at a point on the American shore, not so very far north from the end of
that Fall.
When white men first settled near the Cataract, in the first decade of
the 19th Century, the location of the "Indian Ladder" was amongst the
present overflows from the mills of the Lower Milling district. That,
by reason of the "debris slope" of the Gorge being highest at that
point, had doubtless been its location for ages.
The fact that, even at the most accessible (and that by no means easily
reached) end of the Fall in the Gorge, the entire conditions of the
Legend could so rarely be fully complied with, would have been to the
unscientific minds of the Savages only an additional incentive to a
firmer belief in it.
It is also observable from the rocks beyond and below Terrapin Point,
on the Goat Island side of the Horse-Shoe Fall; but the climb out to
that point is both arduous and dangerous, and is very rarely attempted.
No such phenomenon can be seen from the Canadian shore, because there
are no rocks out in front of that end of the Horse-Shoe Fall on which
one can stand.
Were one to stand upon the apex of the Rock of Ages, or on the apex of
any other high rock at the base of the Fall, at noon, when the sky was
clear above, and the currents of air happened to surround the base of
that rock on all sides with spray, as one turned completely around one
would be in the center of a complete circular Rainbow--which would be
below the level of the feet--and of which one would see but the half at
any portion of the turn.
At Niagara, when one gazes on a complete circular bow, as seen against
the perpendicular curtain of spray, the center of the circle will
always be lower than the point where one is standing. This is
necessarily so, from the very nature of things,--because the Sun, one's
head, and the center of that circle must be in a line.
When the point of observation is high enough, and the spray-cloud
spreads out extensively enough, it is possible to see two concentric,
complete Rainbows at one time. In fact, one does often see a portion of
the arc of such a second bow; but three complete concentric bows, or
three arcs of bows, are never seen at Niagara, nor anywhere else.