I was reading a booklet called “Sand and Glass” and found some references to railroads that seem worth passing along. Nobody’s jaws will drop in awe but it is interesting, I think.
In 1897 railroad engineers were having problems identifying the hues of signals when visibility was poor. Green, yellow, and red were being confused, even though each is an easily distinguishable tone which is why they were chosen as the basic safety colors. It turned out that in fog or heavy rain the refraction of the water droplets on the tinted lights changed them. And it was found that there were 32 shades of “green” being used, with varying degrees of yellow or blue (and if purple, meaning red) in them. There were also many shades of reds and yellows used.
A sales manager for Corning Glass, Alanson B. Houghton, attended a lecture at the New York Railroad Club by a Yale professor on the topic of color blindness, and he hired the professor to establish, scientifically, the three hues of highest intensity. In 1908 the Railway Signal Association adopted those hues as standards.
Corning played a role in another glass development for the railroads. Signalmen would take lighted lanterns from warm sheds into cold and snowy nights and the globes would shatter from the temperature change. Serious accidents occured more than once due to this cause. Dr. Eugene Cornelius Sullivan had founded the glass industries first research institute at Corning and in 1912 found that adding boron to glass made the glass hardly expand at all when heated. The borosilicate glass was called Nonex. It had a low coefficient of expansion – and the breakage of signal lanterns was cut in half.
Dave Nelson
That is interesting-how big is this book? I might try an interlibrary loan copy, if it’s not too much to wade through. If too large, I’ll have to wait for more time off.
It is a soft cover booklet, quite possibly written by Corning. You can read it in an evening easily. It is part of a Science Series that was probably aimed at middle high school students circa 1970 but would now probably be regarded as too elevated. Lots of info on glass making and would be a good resource for anyone thinking of a glass factory on their model railroad. I pretty much exhausted the railroad specific discussions, above.
My wife found it for 99 cents at a used book sale. Try the local library including the young people’s section.
Dave Nelson
There was quite an extensive discussion in the scientific journal Photonics about the differences in wavelights between RR red and amber signals in the US and UK in relation to a UK commuter train wreck. Turns out that it doesn’t take much interference or voltage drop in a signal lamp to make amber appear red which is the more restrictive signal. However, environmental conditions or overvoltage in a signal lamp can make red appear amber according to claims made in the UK accident investigation.
dd
Other amusing facts for visual signals…it turns out that the most common wavelength for red LED’s which are now appearing in traffic lights just happens to be the same wavelength which is most attenuated by most popular sunglasses…it would be interesting to know if the RR had specific guidelines for operating personnel wearing sunglasses…
Well that’s a worrying thought…
A side note about red is that it is the first color to disappear in the water. When fishing with red it disappears and turns to gray after about 5 feet of depth or so. Wonder how a dirty signal lens in a wet snow or fog would look like? Just my 2 cents worth.