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Comment by mannykannot | Hacker News Reader

There is an intriguing reference here: "...the concept of a spatial x-ray locating device came to [Steinhaus] during a winter stroll spent observing snowflakes falling on his fur coat." Elsewhere, I have found the comment "Steinhaus designed and instrument for localization of strange bodies in the body of a sick person by means of X-rays, based on a simple and elegant geometrical conception (1938) [1]." Does anyone know what this is? A form of tomography, perhaps, or an application of stereology? - which is distinct from tomography, according to this article [2], and is apparently somehow related to his Longimeter, recently discussed here [3].

[1] http://prac.im.pwr.edu.pl/~hugo/HSC/Steinhaus.htm [2] https://en.wikipedia.org/wiki/Stereology [3] https://news.ycombinator.com/item?id=16647821

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From that description, I would guess a form of focal plane tomography (https://en.wikipedia.org/wiki/Focal_plane_tomography), but http://far.in.tum.de/pub/sielhorst2008jdt/sielhorst2008jdt.p... says

”The first setup augmenting imaging data registered to an object was described in 1938 by the Austrian mathematician Steinhaus. He described the geometric layout to reveal a bullet inside a patient with a pointer that is visually overlaid on the invisible bullet. This overlay was aligned by construction from any point of view and its registration works without any computation. However, the registration procedure is cumbersome and it has to be repeated for each patient. The setup involves two cathodes that emit X-rays projecting the bullet on a fluoroscopic screen (see Fig. 2). On the other side of the X-ray screen, two spheres are placed symmetrically to the X-ray cathodes. A third sphere is fixed on the crossing of the lines between the two spheres and the two projections of the bullet on the screen. The third sphere represents the bullet. Replacing the screen with a semi-transparent mirror and watching the object through the mirror, the third sphere is overlaid exactly on top of the bullet from any point of view. This is possible because the third sphere is at the location to which the bullet is mirrored. Therefore, the setup yields stereoscopic depth impression. The overlay is restricted to a single point and the system has to be manually calibrated for each augmentation with the support of an X-ray image with two X-ray sources.”

> by the Austrian mathematician Steinhaus

Steinhaus was Polish, the confusion probably comes from the fact that he was born in then occupied by Austro-Hungary part of Poland (city of Jaslo, now within borders of Poland).

I've noticed more than a few Poles saddled with non-Polish roots in various history books. Banach himself was at one point incorrectly identified as a Russian mathematician in an old edition of the Encyclopedia Britannica. Sometimes the cause of error may be the historian's ignorance, sometimes nationalistic appropriation by others. Many Poles also often worked abroad during the 19th and 20th centuries because of foreign oppression by the Germans, Russians, and the Austrians (the last to a lesser degree than the first two).

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