Wilhelm Conrad Röntgen: the X-rays discovery

How Wilhelm Conrad Röntgen discovered the X-rays

By Museo della Radiologia

Museo della Radiologia - Sistema Museale dell'Università degli Studi di Palermo

Prof. Wilhelm Conrad RöntgenMuseo della Radiologia

In 1894 Wilhelm Conrad Röntgen, professor at the University of Würzburg, started his experimental research on cathode rays, discovering an unknown radiation able to pass through the objects. In 1895 he realised the first medical X-ray and in 1901 was awarded the Nobel Prize for Physics. Röntgen donated the prize amount to his university and never patented his discovery, deeply convinced that "every discovery belongs to the whole humanity".

Röntgen's experimental systemMuseo della Radiologia

The recreation of the experimental system by means of which Wilhelm Conrad Röntgen discovered the X-rays. On repeating the Philipp Lenard's experiments, Röntgen used a large Ruhmkorff inductor coil (device 3) with a Deprez switch, applying a primary current of circa 20 A. This supplied energy to a Lenard vacuum tube (device 4), connected to a Raps vacuum pump. This device generated "sparks of appropriate length" which have been impressed on a nearby barium platinocyanide screen.

BatteryMuseo della Radiologia

The power supply in Wilhelm Conrad Röntgen's experiments was a rechargeable battery.

Ruhmkorff induction coilMuseo della Radiologia

The photo shows the Ruhmkorff's inductor coil (device n. 3) and, on the left, the Deprez switch. The induction coil was widely used to excite rarefied gas tubes (such as the Lenard tube) for the spectroscopic study, through X-rays. The device consists of a Deprez switch, named after its inventor, placed between the accumulator and the primary winding of the Ruhmkorff's inductor coil. As a whole, the device is an electrical transformer used to produce electrical impulses. The secondary winding is connected to the Lenard tube that emits X-rays.

Lenard X-ray tubeMuseo della Radiologia

The glass element is the Lenard tube, i.e. the X-rays emitter, which is the evolution of the Crookes tube. It consists of a glass bulb, inside which a high vacuum is created. It contains an emitter of cathode-rays which collide against a thin layer of aluminum, called "Lenard window", generating the X-rays emission

Vacuum systemMuseo della Radiologia

The gases rarefaction inside the Lenard X-ray tube is achieved through a mercury vacuum pump, invented by August Raps in 1891. This device, derived from the "Geissler-Toepler" pump, is equipped with an automatic mercury flow control system, composed of the interrupters placed on the right (5). A similar system was widely used to create vacuum in the industrial production of light bulbs.

Raps vacuum pumpMuseo della Radiologia

Vacuum control systemMuseo della Radiologia

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© Property of the Museo della Radiologia - Sistema Museale dell'Università degli Studi di Palermo

Curator: Giuseppe Genchi
Collaborators: Claudia Cirrincione, Fulvio Sardina, Claudia Lo Re

Bibliographical references:
Adelfio Elio Cardinale, Roberto Lagalla, Massimo Midiri, "Il Museo della Radiologia". Edizioni ZAcco, Palermo, 2018. ISBN 9788894582383

Adelfio Elio Cardinale, “Immagini e segni dell'uomo, storia della Radiologia Italiana”. Casa Editrice Libraria Idelson, Guido Gnocchi Editore, 1995. ASIN: B00GMMWPL2

Credits: All media
The story featured may in some cases have been created by an independent third party and may not always represent the views of the institutions, listed below, who have supplied the content.
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