Arizona weekly journal-miner., 1893-02-08
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Some PoPalar Errsrs Corrected by the
 Photographs Lsns.

Some repalas Errsrs Corrected by ths
 Photographs Lsns.
 Several traits of lightning have been discovered by photography that were not previously suspected. This is particularly true of the course taken by thunderholt. So ephem. eral is the fiash-it seldom lasts over two hundredth part of a SIC ond, and some authorities say that occasionally it endures only a mil. honth--that tho eye can distinguish little beyond the general route trav- ersed.
 The poetic and popular conception of the path of lightning is that 1t is a series of Eigzags much sharper than those of Virginia rail fence. Pho tography proves, however, that tho track does not contain a single angle but is sinuous. like q river. It is a curious fact that in 1856, before this fact was thus established, Mr. James Easmith declared to the Brit ish Association for the Advancement of Science that he had never ob served the xigzag form of lightning, but that to his eye the fash always appeared, as in a diagram which he odercd. showing only curves and with or without branches or forks.
 It k now evident that he was an exceptionally keen observer Photo graphs reveal not only the sinuosity of tho track, but also the ramified character of many flashes Some times the tilamenss hiverging from the main line arc numerous and deli cate as the rootlets of a trS,e or the small tributaries to river. Whether these branches flow intoo or out of the principal stream it is not easy to say, yet electricity often discharges itself by a number of routes. the quantity of fund taking each one being in pro portion to the oonductiyity of the ail or other substance through which the current at that point posses.
 These photographs of ramified lightning render much more intelli gible than was formerly the case some of the stories of thunderbolt freaks unquestionably. instead of one solitary current skipping to and tro around the room or among sev- eral buildings. as has been supposed was the case in several instances. the stream has divided into several. each taking a tolerably direct course to the earth.
 Besides the sinnous and raInified types. photography shows the exist ence of q Tibl,onlil-e fsreak. fiat. thin and wavy. quite distinct from other forms Then, too. there is the me andering" variety, which wanders al over creation without any distinct aim Still another rcoori made by photography is called dark light ming. becanse the streak produced when a print Is made from the neg gtive is black and not white. Pre- cisely how this effect is caused has not yet been satisfactorily explained. One suggestion Is that It Is due to overexposure of the photographic plate. A similar rt,sult k obtained with the sun sometimes. where the very intensity of the light revenses the effect It might also, 1t is thought, be produced by previous flash occurring just before the plate was exposed and leaving a line of nitrous oxide in tine air along it's route
 A subsequent flash. slightly far ther away, would illuminate the whole field. but fail to penetrate this streak. Absorption of the rays would occur somewhat as in tho case of a gas in the spectrum--New Haven Palladium.