[10] For convenience to those wishing to verify the calculation of these
triangles, we have put down each side and angle as found. Also, as an
aid to the navigator.
[11] Daily Wisconsin, July 7.
[12] The author.
[13] Chicago Democrat.
[14] This was also calculated before the event.
[15] The letters in a parenthesis signify the direction of the wind.
[16] Giving this cloud the average velocity of thirty miles per hour,
its altitude was determined by the sextant at twelve miles, and we think
under-estimated. While measuring, the author's attention was drawn to
the fact, that although it appeared equally dense above and below, yet
its middle part was the brightest, and as there was only a faint glimmer
of twilight in the N.-W., he concluded that the cloud was self-luminous;
for when the smallest stars were visible, it glowed about as bright as
the milky-way in Sagittarius. Occasionally the whole cloud was lit up
internally by the lightning, and about this time it sent off three rays:
one horizontally, westward, which was the faintest; one about N.-W.,
towards Jupiter, and the brightest of the three; and another towards the
north. These were not cirrus streaks, but veritable streams of electric
matter, and had a very decided rotation from left to right, and
continued visible about twenty minutes, as represented above.
[17] This day the central vortex passed in about latitude 47d N.--the
southern margin cannot be nearer than 250 miles, throwing off the 40'
for the horizontal refraction, would give eight miles of altitude above
a tangential plane. Then another seven miles, for curvature, will give
an altitude of fifteen miles for the cumuli. The height of these
thunder-clouds has been much under-estimated. They seem to rise in
unbroken folds to a height of ten and twelve miles frequently; from the
data afforded by the theory, we believe they will be found much higher
sometimes--even as much as sixteen miles.
[18] These parallel bands, and bands lying east and west, are frequent
in fine weather between two vortices. Sailors consider them a sign of
settled weather. After dark there was frequently seen along the northern
horizon flashes of lightning in a perfectly clear sky. But they were
both faint and low, not reaching more than 4d or 5d above the horizon.
After sunset there were very distinct rays proceeding from the sun, but
they were shorter than on the evening of the 3d. These are caused by the
tops of the great cumuli of the storm, when sunk below the horizon,
intercepting the sun's rays, which still shine on the upper atmosphere.
The gradation was very marked, and accorded with the different distances
of the central vortex on the 3d and 4th--although, on the 4th, the
nearest distance must have been over four hundred miles to the southern
boundary of the storm.
[19] It is worthy of notice here, that New York, which only differs by
about 40 miles of latitude and 800 in longitude, had the storm earlier,
near the time of the passage, as appears by the appended account of it.
This proves, that a storm affects a particular latitude simultaneously,
or approximately so. If this had to travel eastward to reach New York,
it would have been the 10th instead of the 8th. The principal trouble
was, however, in the early part of the evening of the 8th, to the south
of Ottawa, where the strong wind was drawn in from the northward. If a
vortex passes from north to south, leaving the observer between the
passages, there must, nearly always, be a winding up squall from the
north to clear away the vapory atmosphere.
[20] From the _New York Tribune_, July 9, 1853.
[21] These pages are now in the compositors' hands, (Nov. 21st,) and up
to the last moment the Author has observed carefully in New York the
passages of these vortices. October 24th, in the inner vortex descending
produced a violent storm on the coast, and much damage ensued. November
7th, the same vortex ascending was also severe. And on November 13th,
early, the passage of the central vortex ascending, caused a flood in
Connecticut of a very disastrous nature. Would it not pay the insurance
offices to patronize such investigations in view of such palpable facts
as these?