The daily morning journal and courier., 1901-09-06
FACTS ABOUT LIGHTNING.
Common Errors as to Its Nature and
 Its Destructiveness.

| Its DestructiVeneSs.
 | Without doubt lightning was the frs
 electrical phenomenon that was ever observed by human beings. To this
 day it remains the least known ant least understood of natural electrical
 manifestations, except, perhaps, the | aurora.
 There is a vast deal of popular mis- l conception concerning the danger of lightning and the nature of it. The l lightning flash is discharge from a cloud at high potential with reference l to the earth. When the atmosphere Is l charged with water. vapor and some eddy or current in it's colder upper strata is deflected downward, causing condensation and exceedingly minute drops of water are formed, each bear ing an electrical charge. The consolida-
 tion of these into larger drops results in very great increment of the po-
 tential of the charge, since the capacity
 of the drop varies with its diameter
 and the volume of the drop with the
 cube of the diameter.
 The consequence of this is that it
 takes, for example, eight drops con-
 solidated to make one of twice the di-
 aneter of the constituent drops, and
 the charge on the surface of the con-
 soidated drop will be four times as
 great as that upon the surface of its
 elements. In this way, as the small
 water particles unite to form drops
 which fall as rain the potential of the charge they carry increases until it at
 tains enormous values and the light
 ming flash to the earth, which may be regarded simply as a body of very great electrostatic capacity. This dis charge. whichi is called lightning, is apt to be more or less destructive, although the energy of an individual fish is per haps not very great.
 Often the conditions are such that the discharge takes on an oscillating character, producing violent surgings of current. No very accurate measure ments have been made upon the cur rents involved, but 1t is taken to be of the order of 1000 to 5000 amperes. The electro motive force necessary to cause 6 flash a mile long is probably several million volts. and, of course, the pow CT of the flash measured In waits is very great, but it's duration is corre- spondingly short
 Protection of property and life from lightning flashes has been subject that has entrained the attention of nat ura philosophers since Franklin sent up his historic kite. The net result of more than a century of attempt to se- cure protection has been the lightning t,,rf TJota and the discovery that buildings of modem construction having metallic roofs and often metallic frames IS well, are practically immune from attack by lightning The total number of deaths due to lightning in any given summer Is comparatively very small-in the ra- tio of about one to each 200, GOO popu- lation in the United States.
 In cities the destructive influence of
 lightning is exceedingly small, al though occasional fires are caused by t, especially where gaspipes abound. of electric circuits from lightning has been an interesting sub- ect for research for a number of years. md several highly efficient devices nave been constructed for this purpose.
 To- day, lightning is little feared by he station superintendent and should be very little feared by any one. The time- honored rule that it is wisest to seep in the open and not seek the shel- CT of trees is one which common pru- fence dictates. Recourse to the feather )ed of our ancestors, however, is no onger necessary, except to quiet the lerves of timorous persons, while the ncient superstitions regarding hand | ing steel instruments and sitting in l Iraught may be utterly disregarded. A | modern building in a city is as nearly | bsolutely lightning proof and those in | t are as nearly absolutely protected | rom lightning as is possible | Electrical Review.