The Montgomery advertiser., 1902-01-19
Facts About Lightning.

The Electrical Review.
 Without doubt lightning was the first electHcal phenomenon that was ever ob- served by human beings To this day 1t remains the least known and the least understood of natural electrical manifes- tations, except, perhaps. the aurora.
 There is a vast deal of popular miscon- ception concerning the danger of light ming and the nature of it. The lightning flash is a discahrge from cloud at q high potential with reference to the earth. When the atmosphere Is charged with water, vapor and some eddy or cur rent in its colder upper state is deflected downward. causing condensation, and exceedingly minute drops of water are formed, each bearing upon the electrical charge. The consolidation of these into larger drops results in very great incre- ment of the potential of the charge, since the capacity of the drop varies with it's diameter and the volume if the drop with the cube of the diameter.
 The consequence of this is that 1t takes. Tor example, eight drops consolidated to make one of twice the diameter of the constituent drops. and the charge on the surface of the consolidated drop will be fCur tim?S Us great as that upon the sur face of it's elements. In this way, as the 5nall water ~articles unite to form drops which fall as rain. the potential of the charge they carry increases until 1t at talns enormous values. and the lightning Hash leaps to the earth. which may be regarded simply as d body of very great electrostatlc capacity. This discharge, which is called lightning, is apt to be more or less destructive. although the energy of an individual flash is perhaps not very great.
 Often the conditions are such that the discharge takes on an oscillating char acter. producing violent surgings of cur rent No very accurate measurements have been made upon the currents in- volved. but it is taken to be of the'order of 1000 to 5000 amperes. The eleetro- motive force necessary to cause a flash mile long is probably several million volts. and, of course, the power of the nash measured in watts is very great, but It's duration is correspon1inSly short.
 Protection of property and fife from lightning flashes has been a subject that has entrained the attention of natural philosophers since Franklin sent up his historic kite. The net result of more than q century of attempt to secure pro- lection has been the lightning rod in its more or less inefficient forms, and the discovery that buildings of modern construction having metallic roofs and often metallic frames as well arc prac- tically immune from attack by lightning. The total number of deaths due to light ming in any given summer is compara- lively small-in the ratio of about one to each 2OO,UUO population in the United States.
 In cities the destructive influence of lightning is exceedingly small, although occasional fires are caused by 1t, eSpe- cially where gas pipes abound. Protec- ton of electric circuits from lightning has been an interesting subject for re- search for number of years. and sev- eral highly etncient devices have been constructed for this purpose.
 Today lightning Is little feared by the station superintendent, and should be very little feared by anyone. The time honored rule that it is wisest to keep in the open and not seek the shelter of trees is one which common prudence die tates. Recourse to the feather bed of essary. except to quiet the nerves of timorous persons, while the ancient su- perstitions regarding handling steel in- struments and sitting in a draught may be utterly disregarded. A modern build ing in city is as nearly absolutely pro- tected from lightning as is possible.