Notices of Tornadoes, &c.

  • Hare, Robert, 1781-1858.
Date:
[1840]
Catalogue details

Licence: Public Domain Mark

Credit: Notices of Tornadoes, &c. Source: Wellcome Collection.

Provider: This material has been provided by the Harvey Cushing/John Hay Whitney Medical Library at Yale University, through the Medical Heritage Library. The original may be consulted at the Harvey Cushing/John Hay Whitney Medical Library at Yale University.

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    yards from Chatenay, divided into two parts, one of which disap- peared in the clouds, the other in the ground. . ^ In this hasty account I have, with the intention of returning to this portion of the subject, omitted to speak particularly oi 1 s effect upon trees. All those which came within the influence ot the tornado, presented the same aspect; their sap was vaporized, and their ligneous fibres had become as dry as if kept for forty eight hours in a furnace heated to ninety degrees above the boiling point. Evidently there was a great mass of vapor instantaneously formed, which could only make its escape by bursting the tree in every direction ; and as wood has less cohesion in a horizontal longitu- dinal than in a transverse direction, these trees were all, throughout one portion of their trunk, cloven into laths. Many trees attest, by their condition, that they served as conductors to continual discharges of electricity, and that the high temperature produced by this passage of the electric fluid, instantly vaporized all the moisture which they contained, and that this instantaneous va- porization burst all the trees open in the direction of their length, until the wood, dried up and split, had become unable to resist the force of the wind which accompanied the tornado. In con- templating the rise and progress of this phenomenon, we see the conversion of an ordinary thunder gust into a tornado ;* we be- hold two masses of clouds opposed to each other, of which the upper one, in consequence of the repulsion of the similar electri- cities with which both are charged, repelling the lower towards the ground, the clouds of the latter descending and communi- cating with the earth by clouds of dust and by the trees. This communication once formed, the thunder immediately ceases, and the discharges of electricity take place by means of the clouds which have thus descended, and the trees. These trees, tra- versed by the electricity, have their temperature, in consequence, raised to such a point that their sap is vaporized, and their fibres sundered by its effort to escape. Flashes and fiery balls and sparks accompanying the tornado, a smell of sulphur remains for several days in the houses, in which the curtains are found dis- colored. Every thing proves that the tornado is nothing else than a conductor formed of the clouds, which serves as a passage * See 5th vol. of the American Philosophical Transactions, or Silliman's Jour- nal for 1837, vol. 32, page 154.