Show Making Makin Electricity Elect I of Light What is light This has been the query not only of the scientists but butof butof of the philosophers of every age Modern research brings us one step nearer the solution of ot Ithe the problem by showing this cause to be closely connected connected connected con con- with one of the fundamental questions of recent t years What is electricity ele An answer to the first of of these questions is is' ventured ventured yeI tu by the modern eW electronic tr ic theory of the con constitution of oi matter matter On this view all sub sub- stan stan es c contain within their atoms a number of exceedingly small aggregations aggregations t ons each carrying a a negative charge Suppose explains explains' Dr Bergen Davis of Columbia university in the New NewYork NewYork York Times the ilie circle in Fig 1 to represent an atom the dots dots' within t to represent these small charged centers cente centers cen cen- te s. s the electrons and nd the shaded r f DR DAVIS DAVIS' APPARATUS APP RATUS portion sufficient sufficient nt positive electricity to fo make the atom electrically n neutral Any given number umber being present these electrons electrons' will occupy certain definite positions positrons with with regard regard to one another within the atom If now some outside force displaces displaces' one of these electrons from its position of equilibrium the force within the atom tending to pull It back to its original place will cause ause it to vibrate and this vibrating charge will be the origin of ether disturbances The oscillations succeed one another with extreme rapidity and so we have an t magnetic electro-magnetic disturbance of short wave length which affects our senses with the sensation of light Knowing then that light Is due to electrical the question naturally arose as to whether or not it would be possible to convert sunlight sunlight sun sun- light directly Into electricity To this Interesting and valuable subject of ot Investigation in investigation investigation in- in Bartoli an Italian Italian j east cist gave some attention In In 1881 he performed perfo an experiment with this as the object and claimed success l He e arranged a conducting film pim of silver silver sil sll ver so that it could he be moved with very very great velocity the ends of the tUrn film film being connected with a galvan galvan- ometer The film was then set in mo mo- while tion a a. a bright ray of sunlight fell c upon it Bartoll Bartoli claims that when light was thus allowed to fall on the the moving film a small deflection was observed thus Indicating the presence of a current current current cur cur- rent of electricity He also states t that t when t the e film was at rest there was was no no deflection also upon reversing the direction of the motion of ot the thEt film film t the e deflection of the ter was was reversed Believing that the confirmation of such s ch a direct c conversion of the electromagnetic electromagnetic electro electro- magnetic waves of light Into electricity elec- elec I was of fundamental importance Dr Davis constructed a more sensitive sensitive tive apparatus than that of Bartoli designed designed de de- signed upon a somewhat different plan The method employed was to place a athin athin athin thin film of silver on a glass plate or disk A In F Figs gs ll II II III which was wasso wasso so thin as to be translucent The ends of this film were connected by by- wires vires w w running through a hollow hollow hollow hol hol- low steel axle B to a very sensitive galvanometer The disk carrying the film was then then- set in motion making approximately revolutions revolutions' a second and sunlight concentrated upon the film by means of a pow powerful lens X In the first experiments performed some slight deflections of the galvanometer galvanometer galvan galvan- ometer were noticed but in later trials when greater greater- care was taken to avoid all extraneous causes of disturbance no deflection could be obtained on the th galvanometer no matter whether th film was revolving rapidly or W was entirely en ea at rest rest- J j J |