ARTIFICIAL LIGHTNING.

Hokitika Guardian, 14 November 1924, Page 4

ARTIFICIAL LIGHTNING.

A NOTABLE EXPERIMENT. (fly Science Service! How lightning is made and how to make it was the topic of the address of E. \v. Peek. jii u.. at the centenary of the Franklin institute at Philadelphia on September 1 i th. 'I he generator for the production of artilicial lightning constructed at the research hihoral ir.v of the General Electric Company at Pittsfield. Mass., gives a discharge of J.CTI.I'T) volts, which is about J tier cent, of the voltage of natural lightning, and stillieicnt to afford opportunity for the experimental study o| (he idfects of lightning on buildings au'il power transmission lines. A thunder . loud . c.-i rl \ i llg a <ha ler ol . .I \ . a hundred million volts, may. bv a Hash ol lightning to earth, discharge this hut ilen of elect ricitv within a few millionths of a second in a current of 80.00'> amperes. The voltage of the cloud is thus reduced, to zero, or it mnv acfpiire almost instantly an opposite charge. Ileeau-e Icctricilv is discharged at such a rapid rale the power developed is enormous, often amounting to several thoie-and million horse-power. which is more than is developed by all the steam engines and water wheels of the world. Act the total energy is not so great, as it seems, no more than enough to run an automobile five miles or keep a toaster going all dav. These researches in high voltage will cause a revision of popitlui ideas ol the i ll'ects of lightning and give us more exact knowledge on the protective action ol rods. .Mr Peel; said on this point: “Ite-earelies in the laboratory show that lightning from a cloud overhead does not always strike the highest object or rod unless the height of that object is over 2.5 per cent, of the cloud height. The division ol hits is about ci|iial between elolld and ground when the 101 lis 1.1 per cent, ol the eloiid height. The chance of being hit is less when the cloud is nut directly overhead. Lightning either strikes the rod or some distance away. There is a protected area around the rod with a radius eipial to lour times the height of the rod where no ground hits occur.

“These resnrclies show that a man standing directly under the storm centre would he hit fifteen times out of a hundred strokes, while a man flat on the ground would he struck about once in a hundred strokes. A 25-foot building would be struck every time. The chance of a thunder cloud of siillieient voltage to cause a discharge being over any particular object is small. The chance of any particular object being struck is thus generally vety small indeed.

“The lightning rod seems to he o real value for the protection of build ings. Except for buildings in exposet positions or in special cases, as maga zincs, the cost of a rod. unless it i* quite low. is nut, warranted from tin standpoint of the oat of insurance.”