The Electric Thief-Catcher 



It rings a bell, takes a photograph of a burglar, 

 and shoots him as soon as it sees his flashlight 



IJv 15. F. Miissner 



ALTHOUGH this api^aratiis accoin- 

 A-\ jilishcs some startling ri-siilts, the 

 idea of seleiiiuni-aetiiated Iiurgiar 

 alarms is not altogether new. M. Dafah, 

 a French engineer at J ansae, suggested 

 the use of selenium for this purpose 

 several years ago; others have worked 

 along similar lines. 



It may he mentioned here that no 

 atteiTipt has been made to obtain 

 I):itents on this apparatus; its use is 

 unrestricted, and any one with the 

 inclination may cop\- this arrangement 

 for his own use or pleasure. 



But what is this Electric Thief- 

 Catcher? How can any machine or 

 electro-mechanical contrivance catch a 

 thief? 



In the first place it does not catch 

 him, if b\' catch is meant to ])ursuc and 

 seize, and perhaps to march him to the 

 fKitrol wagon or jjolice station. If by 

 catching is meant to trap, then we may 

 safely say that it does exacth- that, and 

 it can be made to do it as efl'ectivcly as 

 you please. The writer very narrowly 

 escaped being quite effectively caught, 

 when on one occasion this a])paratus 

 sent a thirty-two caliber bullet through 

 his coat-sleeve! 



By "as effectively as \ou i)lease" is 

 meant that the "catching" can be ^■ariecl 

 all the way from mercK' sending in an 

 alarm, to frightening the intruder awa>-, 

 or actually shooting him dead. 



All that is reiiuired of the burglar is 

 that he possess a light of some kind, if 

 it be onl>' a match or a pocket llash- 

 light, and that its rays fall u])on the 

 acute and e\er wakifui cxc of this 

 hilden apparatus. 



This electrical e>e is a selenium cell 

 such as is shown in one of tiie accom- 

 pan\'ing illustrations. All that it can do 

 is lo record its impressions by sending 

 an impulse to the electro-mechanical 

 brain of the apparatus, when stimulateil 

 by a liglil. Th.il impulse is a surge of 

 electric ( tuK 111 wluii ilic resistance of 



the cell drops, due to the effect of the 

 light. The cause of this curious effect 

 is not yet understood but is being in- 

 \"estigated b>' se\eral men, among whom 

 is Professor F. C. Brown, of the Iowa 

 State Uni\-ersit\-. 



The brain is a sensitive rela\-, prefer- 

 ably one such as is used in the Electric 

 Dog, which was described in the March 

 number of Popular Science Monthly. 

 This brain has the power to stimulate 

 an>' one or an\- number of a great \'ariety 

 of electro-mechanical muscles, and to 

 produce a corresjionding \-ariety of 

 actions. In the writer's apparatus one 

 of these was an electric gong, the 

 burglar alarm; another an ordinar\ 

 revob'er whose trigger was pulled by an 

 electromagnet; a third was a camera 

 whose shutter was opened by a cord 

 attached to the .same electromagnet; 

 a fourth, a charge of flashlight powder, 

 which was set off In- the heating of a 

 short piece of tine resistance wire; and 

 on one occasion a hftii was a phono- 

 graph with a specially prepared record, 

 which, without a doubt would frighten 

 (jut of his wits the boldest thief who 

 heard its weird and uncanny warning. 



Here, then, we ha\c an electro- 

 mechanical creature, which, hidden from 

 all view, and witii no human agency, will 

 fire a re\-olver, send in an alarm, set off 

 a charge of llash powder, and take the 

 lihotograjih of an\- marauder who prowls 

 about with a light. 



Dining tl\e course of a lectiiit- before 

 tile Chicago Electric Club and the 

 National IClectric Light Association, the 

 author in the guise of the burglar 

 stepped lip In the iilatforin in the 

 darkened li'ctini' hall, ll.ishlight in h.ind: 

 till' instant the light fell upon the eye, 

 I he revoU'er began firing, the bell rang, 

 tiu' canu'ra-shutter opened, the llash- 

 lighl powder exploded, and the photo- 

 graph on the following page resulted, 'n 

 another lecture .i phonogr.iph w,is use<I 

 and for five minutes therewasenactinl the 



l.H\ 



