16th. Clear morning (N.-E.); 3 P.M., getting very black in E. and S.-E., very _clear_ to the _westward_; 4 P.M., much thunder and lightning in east, and evidently raining hard; 5 P.M., a violent squall from _east_ for 10 minutes; tore up several trees; 6 P.M., the storm passing eastward, clear in west all this time; 6.30 P.M., the storm forming a regular arch, the vertex being in _S.-E._; the arch of hazy cirrus and heavy cumulus much lower in S.-E., wind still moderate from east; 10 P.M., clear all around, but lightning in S.-E. and E. 17th. Fine clear morning (W.); noon, scattered cumuli in north; 6 P.M., a beautifully regular arch of dense cumuli and cirrus margin in _N.-E._, with a constant glimmer of lightning; 7 P.M., very clear to the west, and north-west, and south; along the northern horizon a line of high peaked cumuli terminating in N.-N.-W.; a continued roll of distant thunder in the circular bank in N.-E., and not a moment's cessation to the lightning; the electric excitement advancing westward along the lines of cumuli; the cirrus haze also rising and passing towards S.-W.; 8 P.M., the sky alive with lightning, the cirrus now reaches the zenith; no streaks of lightning coming to the earth; they seem to radiate from the heaviest mass of cumuli, and spread slowly (sufficiently so to follow them) in innumerable fibres over the cloudy cirrus portion of the sky; every flash seems to originate in the same cloud; 8.30 P.M., one branching flash covered the whole north-eastern half of the sky, no leafless tree of the forest could show so many branches; 9.30 P.M., all passed to S.-W. without rain, leaving behind a large cumulus, as if it lagged behind. From this cumulus a straight line of lightning shot up 10° above the cloud into a perfectly clear sky, and terminated abruptly without branching. We have been thus particular in giving these details, as this was a clear case confirming the principles advanced, that the vortices do not form a continuous line of disturbance, in their daily passage around the earth. It shows also that the barometer, in connection with these principles, will be a far more useful instrument than it has yet proved itself, for practical service as an indicator of the weather. FOOTNOTES: [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.