A cikin 1920s, saka hannun jari katako ya fara bayyana a cikin shagunan takalmin Amurka - Fitowa mai dacewa. Ka'idar aiki mai sauki ce: shigar da kafa a cikin dakin ƙasa, ana iya ganin mai siye da mai yiwuwa ta hanyar bututu na musamman ta yadda yake zaune a ƙafar. Na'urar ta yi ihu da ƙafa ta hanyar, don haka kuna iya ganin kowane kashi da kuma jigon ƙwallon ƙafa.
Wannan shine yadda yake bayyana Vladimir Nabokov a cikin "Dara":
"An yi mu'ujiza ta hanyar mujallar kafa, amma ta hanyar shiga, motsi ya makanta cikakke: Motsa yatsunsu a ciki ba a bayyana a cikin duniyar fata mai laushi ba. Mai siyarwa da mai siyarwa tare da saurin mamaki ya buga ƙarshen layin - kuma ya taɓa takalmin soken takalmin tare da yatsunsu biyu.
"Kawai!" Ta ce. Sabuwar koyaushe kadan ... "Ba a ci gaba da yin barazanar ba, amma suna iya sanya kanka a ƙarƙashin diddige. Amma suna iya sanya kanka ! " Kuma ta sa shi zuwa ga X-ray, ya nuna inda zan sa kafa. Kallon taga ƙasa, ya ga nasa, duhu, yana rarrabe gidajen abinci akan wani haske.
Na'urar ta fara kama da shagunan takalmin Arewacin Amurka da Turai. A Ingila, an kira shi pedoscope, a Jamus - Shucoskop. Pedoscope (shi ne mai walƙiya) kayan kwalliya na Milwauehue). Farashin wani "Kulle mai tushe" tare da x-ray ya bambanta daga $ 800 zuwa $ 1000.
Duk da babban farashi, kowane mai shagon ya nemi samun matsayin sabon abu. Babban yaduwar bayyanar cutar: mutane sun nemi zabi takalma tare da hankali domin ba za a iya sawa kuri ba. Kasuwancin masu mallakar sun kasance masu ban mamaki, yayin da ƙarshen 1940s, masana kimiyya ba su yi magana game da yadda mugayen waɗannan na'urori ba.
Ba su tunanin barazanar masu sayayya: Aƙalla babu raunin da ya faru. Yawancin masu siyarwa sun sha wahala: hannayensu a kai a kai sun faɗi a ƙarƙashin tasirin zafin rana (matsakaita na 114 md / h), lokacin da suka faɗi ƙafafun abokan ciniki. Wannan ya haifar da dermatitis da sauran cututtukan fata. Ofaya daga cikin mafi yawan raunin da ya shafi aikin pedroscope an rubuta shi a cikin ƙirar takalmi, wanda a sakamakon radiation ya yanke hukuncin kafa.
'Yan majalisu duniya a hankali ne a hankali suka iyakance amfani da pedoscopes (haka, yara na iya amfani da su kawai sau 12, wanda a hankali a cikin shagunan da 1960, kuma a ciki Burtaniya da Kanada - a 1970 -M.
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