Of the conclusion arrived at by a committee of the Academy of Sciences of France, agreeably to which, tornados are caused by heat : while, agreeably to Peltier's report to the same body, certain insurers had been obliged to pay for a tornado as an electrical storm, also, abstracts from Peltier's report : moreover, quotations shewing the ignorance which existed in the Academy respecting the nature and causes of the meteor in question, prior to the publication ascribing it to a convective discharge of electricity : with objections to the opinions of Peltier and Espy / by Dr. Hare.

  • Hare, Robert, 1781-1858.
Date:
1852
Catalogue details

Licence: Public Domain Mark

Credit: Of the conclusion arrived at by a committee of the Academy of Sciences of France, agreeably to which, tornados are caused by heat : while, agreeably to Peltier's report to the same body, certain insurers had been obliged to pay for a tornado as an electrical storm, also, abstracts from Peltier's report : moreover, quotations shewing the ignorance which existed in the Academy respecting the nature and causes of the meteor in question, prior to the publication ascribing it to a convective discharge of electricity : with objections to the opinions of Peltier and Espy / by Dr. Hare. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    12 of the aerial atoms in rows, like iron filings situated between poles of s magnet. Hence the same electrifying causes which induce in the ex- treme surfaces a reciprocal attraction, cause in the intermediate atoms a proportional indisposition to undergo the derangement which any obedi ence to that attraction would involve.'*' Objections to Espy^s Hypothesis.—It is well known that, when suddenlyf- rarefied, air is refrigerated; hence, when a receiver is first subjected to ’ ' exhaustion, a cloud appears within it, arising from the condensation ol aqueous vapor. Dalton found that when the air thus rarefied was devoid of aqueous vapor, it became much colder than when this vapor was present.; This he ascribed to the latent heat given out by aqueous vapor on con-i ;) densing. Before I had the pleasure of knowing Mr. Espy, I contrived an apparatus for showing the cold and cloud produced by rarefaction.itJ Silliman\s Journal, Vol. 13, p. 4. This apparatus, as well as that employed by Dalton, does not differ It essentially from Espy’s nephelescope, which is the name given by him to*>u 1(1 * If when there is a great accumulation of electricity, sufficient for the emission of light- ning, we suppose the atmospheric stratum which holds the charge to perform the part of lit the glass in a charged pane, the cloud and the earth acting as coatings, the following ftl rationale may he countenanced by the facts. -A This rationale assumes that electricity consists of opposite polarities, resulting, as Fara- day supposes, fi om an ‘‘action” of atoms in proximity, or as I infer, from a polar affection '. resulting from the polarization of ethereal matter associated or combined with ponderal)lef matter. The same reasoning would apply were the hypothesis of two fluids assumed, in P which the phenomena are ascribed no less to repulsion than to attraction. liCt us suppose a stratum of the atmosphere to be situated just above the height of three i.* miles, and of course to have only half the mean density of a stratum resting on the terres-!, trial surface. Let it be supposed that these strata arc oj)positely electrified, as in the case of thunder storms. Of course, the oppositely excited strata will have a tendency to ap-ig' proach each other, while the terrestrial surface, similarly electrified with the lower stratum, will repel this, simultaneously attracting the upper stratum. But will the attraction of the earth for the sparse and remote air of the upper stratum balance the repulsion exercised by it towards the contiguous and denser stratum below'? Will not the force in the latter instance be greater, first, because, in the same space, there are twice as many atoms to repel, and in the next place, because they are in proximity to the earth? See Si/liaian's p Journal, Vol. y., n. s., p. 345. Again, while the similarly electrified aerial particles in cither stratum must repel each other in consequence of their similar excitement, will not this effect in the lower stratuiiT If be twice as great, (if not quadruple,) in consequence of there being twice as many atonis^ in the same space? Thus while gravitation is counteracted by electrical repulsion, the gaseous elasticity of the air is increased by the same cause. Hence arises an expansive and ascensional powmr. Although the whole of the atmospheric stratum similarly electri- fied by the terrestrial surface must be repelled thereb}’-, yet the force being equally distri- buted, is insufficient to cause the whole to be elevated so as to create a vacuum. It is tl( under these circumstances that either the diruptive discharge may take place in the form ^ of lightning, in which case an intermediate row of aerial particles become instrumental to lay take place by a concentration of the forces on a comparatively minute columnar space. Within the meeting of two opposite waves of electro-polarity; or a convective discharge may take L. in t this space all the forces are exaggerated which have been assigned to the aggregate. j^| Hence, wdiile the aerial elasticity is assisted by a reciprocal electro-polar repulsion, the j whole mass of the air and bodies within the space are violently repelled by the earth. I Hence the expansive power by which houses are burst, and bodies, sufficiently light and r movable, are borne aloft, accompanied by an electrified aerial blast. - An exemplification of this concentration of force is to be seen in the perforation of the b glass of a charged jar. M^ere the mean height of the upper stratum only D miles, the difference of density ^ would be only one-fourth of that assumed, but still evidently there would be a diversity more than sufficient to account for the expansive and ascensional power. ^ I