PHOTOGRAPHING THE INVISIBLE.

Bruce Herald, Volume XXXXIV, Issue 61, 6 July 1908, Page 8

PHOTOGRAPHING THE INVISIBLE.

AMAZING EXPERIMENTS WITH ELEGTKICXi'Y.

- Is it possible to take photographs of the invisible? The answer of the average man would be in the negative, but Mr Frederick Hovenden says it is possible, and is prepared (says the London 'Daily Express') to prove by experiments that not only oan the invisible be photographed, 'but that the results can be reproduced by means of the cinematograph' : Mr Hovenden.. besides being a vice-president of the London Institution,, is a i Fellow of the Physical Society of London, a Fellow of ..-the!: Geographical-Society,„ a 'Fellow of the Linhean Society, and a Fellow of the .Royal Microscopical. He has agreed to give four lectures oh "A Study of the 'Friiiciples of Nature," at ;the- London' Institution, and. in the course. of these lectures he nepes to prove to the satisfaction of a critical audience the truth of the following statements tr(1) That electricity, heat; and ether are the same thing, and consist of a fluid which, if properly illuminated, will be visible to the naked eye. < (2) That it is possible to take cinematograph pictures of the,, invisible. (3)-fThat the ordinary human being exhales- jelectricity or etiier through the pores of tire, skin at the tips .of the ungera. (4)1" vTh&tj photographs 1 ...0f. this, .eleor is produced by the . cinematograph. M^ f H(&v«nden gave a private view; of thfef; principal ■ 'ex|»erimenta >byj;whibhi-• he' claims':to'-prove-hiirtheories to,an. 'Jiixi pr^s , :repre6entatiVe,>and,illust l rated!the manner) in which the photographs l «f*air moving! in duced«at t hifeileoture by < means- of: tfi^ iDuntakfik. ;

HeV first IfittsUa jisciuare;:; glassbox, j whack-is <teohnioally* known- aaH an alya^V from ;<a < .this is -ear^fnlly 1 mixed -iwitEfi.the' ordinary He then a hole an the ; bottom ( ;.0f > the - "analyser/-' and when, the light, from .a -powerful :ele6»3 trie arc ( lamp is iturned ©n,)it'is; quite possible.: to 1 see",the,etlher-r-or electricity —issuing'from* the; hngor^r Mr Hovenden; explains that-thig eta*-, tricity comea-through minute -holes in the top-of-those ridges in the skin by which the police system of identification by finger impressions is carried out. These minute holes are at times . isible to the naked eye when the finger is carefully examined. The electricity can be seen escaping from .the finger even when ,the latter is covered by. a tight-fitting; indiarubher oap. Another experiment proved that, compared witii ordinary oigarette smoke, the air we breathe is jet back. The cork from the hole in the "analyser" was removed, and when,the, powerful light was turned m'oiu the box,> a coal-black stream of air could be seen entering through the opening. Cinematograph pictures of 'this <air have, alaoi beens taken, and.- when thrown- on. the- Bcreen -the minute moleoules of which the air is made up oan be magnified to the size of balls five or six feet in diameter*

Although 'i many ;• scientific c experts maintain- that it is - impossible to see molucles of smoke under a microscope, Mr Hovenden showed them; by means of a special instrument to the 'Express' representative. When greatly magnified they have the appearance of small snakes of .a semi-circular shape which float gracefully through the air, swaying gently first to one side and then to the other. Mr. Hovenden then ilustrated the manner in which he will prove that the fluid which issues through the pores at the ;tip of the finger is electricity. He" placed his finger beneath the metal end of a galvanometer—an instrument which at; once ..records any in the, current of electricity passing through it —and immediately the recording disc showed a considerable inorease in the voltage. This increase was equally noticeable when the finger had the indiarubber cap on it. Another interesting experiment, enables Mr Hovenden to give-the'-appear-ance of flame to any evaporating liquid'. This is done by turning the concentrated rays from the powerful; eleotric arc lamp on the vapor as it rises. It may be mentioned that this can be seen in any factory town where the illuminations reflected from the roaring, furnaces give the appearance of ilaine to the vapor and smoke issuing from the tops of the chimneys.