The fusion of metals is one of the commonest effects of lightning. There are instances of an iron chain being traversed by the lightning, the effect of which was to soften the links so that they united by their own weight, and the chain was converted into a rod of iron. Franklin relates the case of a church struck by lightning, which passed along au iron wire 20 feet long, and about the thickness of a knitting-needle, and dissipated it in smoke, leaving a black trail behind. There are cases also of the discharge passing down bell-wires, destroying them entirely, and leaving the oxides resulting from the combustion impressed upon the walls of the room in broad bands. A year or two ago, a house at Paris was struck ; the lightning broke several panes of ,,glass in a shop front, and burnt away the gilt letters of the word Cafe. In all cases of this kind the conductor is not of sufficient capacity to transmit the discharge, so that the lightning being delayed in its progress, its astonishing heating power becomes developed, and the result is the fusion and oxidation of the metal. According to Harris, a copper rod three quarters of an inch in diameter, or an equal quantity of copper under any other form, is sufficient to withstand the heating effect of any dis charge of lightning of which the effects have ever been recorded. The wonderful heating effects of lightning are manifested in the formation of vitrification and lightning tubes, also known as fu/gurites. [FULOURITE, in NAT. HIST. Div.] These are long, irregular, cylindrical bodies of sand, or other siliceous material, fused into a kind of glass or enamel, and appear to have been formed by the lightning striking and pene trating the rock, and fusing the loose materials together. The outer surface of the tube is often rough and uneven, and deeply furrowed, while the interior may be formed of whitish or limpid vitrified matter covered with a smooth glaze, and hard enough to scratch glass.
When lightning strikes solid imperfect conductors, it tears them to pieces, and scatters their fragments to great distances, just as if a Iwiul expletive force had been suddenly generated within them.
unprovided with lightnintoominctora have had their steeples aud toners destroyed, and heavy silence projected in all direction., to a distance of several hundred yards, elide timber And growing trees are torn into shreds, as if from the operation of same powerful internal force, which Arago is disposal to attribute to high pressure steam, generated by the intense heat of the rigid:Argo acting on the sap of the wired. The mute of ship's have in like manner been I relucel to fragments in a moment. Thus, the log of the Rodney, struck by lightning In December,1538,records the following effects effects:— The topgallant and royal-imst. 53 feet long, weighing nearly 8 cat, entirely distppeares1 from the ship, with the exception of the end of the royal mast The sea was covered with chips and splinters, and "the water alongside looked as if it had received all the refute of a car penter's shop.' Out of twenty-six immerse iron hoops, which were clasped or driven round the nueintnast, thirteen were broken asunder, and came rattling down on the deck with a horrid clang; the ravages of the discharge could be traoed through 53 feet. The lightning had
entered the very heart of the mast, which it charred, and at the paint where the lightning escaped was a hole many inches deep. Caries of this kind are very numerous, and are all marked by somewhat similar effecta, where the lightning has to encounter a nixed systems of good and bad conductors, such as the wood and metal work of a ship, or the stone and metal work of a church-steeple. The lightning will pick out these masses of metal as so many points in the line of least resist ance, and iu order to get at them, will rend and disperse badly con ducting materials ; in short, by its behaviour, It so clearly pointed out the remedy to be adopted, namely, that of furnishing a sufficiently capacious line of conduction froze the highest points of the ship or building to the earth, that we can only wonder at the blindness of architects and engineers In not adopting the remedy; but most of all are wo surprised at the opposition which survived until quite recently at the proposition to supply every ship in her Majesty's Navy with the fixed system of conductors which will be more particularly noticed in the next article.
A very common result of an explosive discharge of lightning, espe cially in a ship not furnished with proper conductors, is to disturb, weaken, or destroy the magnetism of the compass-needle, or to reverse its poles, to render masers of iron and steel strongly magnetic, even to the steel parts of mathematical instruments and the springs of watches and chronometers. Cases of this kind are constantly occur ring, and we need hardly point out the danger ton ship out at sea, with an impaired trompass and chronometer. [Loest Agrneerros.] The action of lightning is every year fatal to man and beast, as well as destructive to property. M. Houdin, in an elaborate work on the subject., has shown that from the year 1835 to 1852, as many as 1308 persons had been killed by lightning in France, which gives an average of six psgsone every month, and this statement does not include those struck by lightning, but not killed. Out of an annual number of 103, the largest number of deaths is in -Tune, in which there are 22, and in August 19 ; no deaths from this anise occur during November and the three following months. The number of persons killed every year by lightning is stated on an average to be, 22 for Eugland, 21'83 for the United States, and 914 for Sweden. The mortality from lightning among the lower animals appears to be more extensive than among human beings, probably from their being congregated together in Luger numbers. This we read of 2000 cheep being killed by a single flash of lightning. This occurred in Ethiopia, and is given on the authority of 31. D'Abbadie. At Sacco, in the kingdom of Naples, In August, 1S58, the lightning killed 120 sheep, out of a flock of 140. Neither the shepherd nor the shepherd-boy was hurt, but a kid which the latter held in his arms was killed. Cases of this kind are not uncommon, in which the shepherd and the huntaman have been spared, while the sheep, the dogs, and the horses have been struck.