Here's a good piece on N-rays and several similar cases of apparent self-delusion:
In 1903, Blondlot, who was a well-thought-of French scientist, member of the Academy of Sciences, was experimenting with x-rays as almost everybody was in those days, The effect that he observed was something of this sort. I won't give the whole of it, I'll just give a few outstanding points. He found that if you have a hot wire, a platinum wire, or a Nerns't filament or anything that's heated very hot inside an iron tube and you have a window cut in it and you have a piece of aluminum about 1/8 of an inch thick on it, that some rays come out through that aluminum window. Oh, it can be as much as two or three inches thick and go through aluminum, these rays can, but not through iron. The rays that come out of this little window fall on a faintly illuminated object, so that you can just barely see it. You must sit in a dark room for a long time and he used a calcium sulfide screen which can be illuminated with light and gave out a very faint glow which could be seen in a dark room. Or he used a source of light from a lamp shining through a pinhole and maybe through another pinhole so as to get a faint light on a white surface that was just barely visible.
Now he found that if you turn this lamp on so that these rays that come out of this little aluminum slit would fall on this piece of paper that you are looking at, you could see it much better. Oh, much better, and therefore you could tell whether the rays would go through or not. He said later that a great deal of skill is needed. He said you mustn't ever look at the source. You don't look directly at it. He said that would tire your eyes. Look away from it, and he said pretty soon you'll see it, or you don't see it, depending on whether the N-rays are shining on this piece of paper. In that way, you can detect whether or not the N-rays are acting.
Well, he found that N-rays could be stored up in things. For example, you could take a brick. He found that N-rays would go through black paper and would go through aluminum. So he took some black paper and wrapped a brick up in it and put it out in the street and let the sun shine through the black paper into the brick and then he found that the brick would store N-rays and give off the N-rays even with the black paper on it. He would bring it into the laboratory and you then hold that near the piece of paper that youre looking at, faintly illuminated, and you can see it much more accurately. Much better, if the N-rays are there, but not if its too far away. Then, he would have very faint strips of phosphorescent paint and would let a beam of N-rays from two slits come over and he would find exactly where this thing intensified its beam.
Well, you'd think he'd make such experiments as this. To see if with ten bricks you got a stronger effect than you did with one. No, not at all. He didn't get any stronger effect. It didn't do any good to increase the intensity of the light. You had to depend upon whether you could see it or whether you couldn't see it. And there, the N-rays were very important ...
At the threshold of observation, some people convinced themselves they had seen something, and, once they had, thought they could construct maps of the 'canals'. But this relied on them having the idea in their head of what they thought they'd already seen.
The Italian astronomer and statesman Giovanni Virginio Schiaparelli reported observing about 100 of these markings, beginning in 1877, and described them as canali (Italian: channels), a neutral term that implied nothing about their origin. Other observers had earlier noted similar markings, but Schiaparellis writings first drew wide attention to the subject. About the turn of the 20th century the American astronomer Percival Lowell became the champion of those who believed the markings to be bands of vegetation, kilometres wide, bordering irrigation ditches, or canals, dug by intelligent beings to carry water from the polar caps. Lowell and others described canal networks studded with dark intersections called oases and covering much of the surface of the planet. Occasionally the lines were perceived as doubled; i.e., two parallel lines became visible where only a single canal had been seen before.
Most astronomers could see no canals, and many doubted their reality. Experiments with untrained observers showed that disconnected features in diagrams or drawings might be perceived as straight-line networks when viewed at the proper distance. Telescopic photography through Earths atmosphere offered no solution, because the lines were barely discernible by the human eye and beyond the recording capability of the camera. The controversy was finally resolved only when close-up images of the Martian surface were taken from spacecraft, beginning with Mariner 4 (1965) and Mariners 6 and 7 (1969). These showed many craters and other features but nothing resembling networks of long linear channels, either natural or artificial.
"War of the Worldviews." It's been republished in Gould's collection "Leonardo's Mountain of Clams ..."
According to Gould, Lowell was convinced (1) that the Martian polar caps were ice and (2) that Mars showed seasonal color changes that could only be explained by seasonal vegetation. He concluded, from his belief in vegetation, that intelligent life-forms must exist, and "deduced" (from his belief that planet water was concentrated in polar ice-caps) that intelligent life-forms must have engaged in advanced engineering activities to move polar meltwater elsewhere -- which fit perfectly with the "fact" that the so-called "canali" had already been "observed" earlier
first read about this in "Betrayers of the Truth". http://www.amazon.com/Betrayers-truth-William-Broad/dp/0671447696 The University of Nancy had just been established at great taxpayer expense and the faculty felt a need to justify the investment, so were quite anxious to discover something important. Not a good situation re. scientific objectivity.
Worth reading: http://www.quackwatch.org/01QuackeryRelatedTopics/signs.html and