new question (Brent Greer's Questions on Markers)

NW Mailing List nw-mailing-list at
Tue Feb 23 11:04:36 EST 2016

Brentonius asks:  Were the markers lit during daylight hours or just when it got dark out? How was this done if it got dark prior to the train stopping somewhere? Was there a rule that governed when they were lit? Also, how long would the kerosene keep the lamps lit before they had to be refilled? 

ANSWERS: Markers had 16 ounce oil pots in them, and the round wick was about two-thirds the diameter of a pencil. The flame was protected against ambient drafts by a Pyrex glass chimney 1.25" diameter X 2.5" high, which shoved down between, and was retained by, four pieces of spring wire affixed to the top of the oil pot. 

These 16 ounce oil pots were the same pots used for switch markers (either in round or square form.) The advertising literature of the day claimed that such a pot, with a properly trimmed wick, could "go a week without a refill." Section men took care of the oil, wicks and glass on switch markers, and they probably hit each one twice weekly. So oil markers would easily burn several days without refilling. 

One very good source (a retired Senior VP Operations from a certain large railroad, and a 1947-hire NYC man) told me yesterday that on the NYC, the practice was for markers to be hung at origin (e.g. New York or Boston,) and run through to destination (e.g. Chicago or St Louis) without change. 

On the N&W, markers were not lit "by day." I have seen a Special Instruction somewhere (probably in an old Time Table) indicating that lighted markers were not required "by day," i.e. that the display of extinguished markers served the same purpose, namely to indicate that the train was complete. And up until the end of marker use, it was the N&W practice that markers were not lit "by day." Of course, prudence was used in regard to lighting markers. If a train were leaving Roanoke at 4pm, the Flagman would probably light his markers before the train left the yard, rather than pulling them down for lighting en route. But I have seen Flagmen on cabooses taking down markers for lighting while the train was on the road. 

Another factor at play in answering Brent's question is the very old principle of railroading (expressed in the operating Rule Books) that "the use of night signals is required from one hour before sunset until one hour after sunrise... and under other conditions where visibility is obscured." This principle/rule goes back at least to the early 1880s, and applied to the display of engine headlights (yes... engine headlights were not "displayed by day" until the mid-1950s!,) the use of flagman's signals, etc, as well as to markers. 

The subject of the colors of glass used in markers is a convoluted topic, as the practice varied from road to road and from time to time. If I recall correctly, the N&W made its big change in the color of rear end markers in 1911. Prior to that date, markers had used Red and GREEN glass, but this was changed to Red and AMBER glass. (Proper word was "amber," not "yellow.") Prior to the change, on the N&W the display of GREEN FLAGS on the rear end of a train was, by day, considered a proper "rear end," but illuminated markers were used by night. 

The above will sound quite strange to you unless you realize that in the old days GREEN was the color used in signals for "DANGER." The old standard signal colors were RED for Stop, GREEN for Danger, and WHITE for Clear. Various roads began the shift from R/G/W to R/Y/G at different times. I think the C&NW may have been one of the first to make the change, that being in the mid-1890s. The stodgy old PRR did not make the change until 1917, following a disastrous rear-end collision on the four-track main line at Mt Union, Pa, caused by a green ("danger") roundel cracking and falling out of a semaphore spectacle, with the result that the following Engineman saw White for "Clear" instead of Green for "Danger." 

Another problem with the adoption of Yellow as a standard railroad signal color was that the manufacturers (Corning being the premier supplier, Kopp Glass being second in line) struggled for years to perfect glass colors having "transmissibility" and "chromaticity" suitable for railroad use, and having not the least variation from batch to batch (or from "melt" to "melt," as they say in the glass business.) Yellow was the last color the glass industry was able to standardize. As I recall, it was in 1913 that the glass industry finally conquered the "Yellow Problem." After all these issues of "chromaticity" were finally resolved, three sets of Railroad Standard Glass were made by Corning: one was sent to the National Bureau of Standards in Washington, one was kept by the ARA (later AAR,) and the final set was kept by Corning. There intended use, of course, was to serve as a "control" against which future productions of glass might be gauged. By 1938, however, the principal source of illumination behind railroad signal glass was changing from an oil flame to an incandescent filament (which produced a color spectrum containing less red and more blue than an oil flame.) So the chromatic standards for railroad signal glass were shifted slightly to accommodate this development, and a second set of "standard glass" was produced, with samples retained by the same three organizations. Thereafter, all signal glass produced had the numerals "1938" in raised letters on on the rim, on the back side of the lens or roundel. To be honest, I am unable to see the difference in colors when I do a side-by-side comparison of 1938 glass with pre-1938 glass. All of this, of course, was under the control of the Signal Committee of the American Railroad Association (later AAR.) The yearly Proceedings of this group make delightful reading, and they frequently had guest speakers from Corning Glass (e.g. the eminent Dr. Churchill,) and all the papers presented by the speakers are published in the Proceedings. (I think the embossing of "1938" was dropped after Lexan came into use for signal lenses.) 

The proper combination of colors in N&W rear end markers at the end of their use was: 1 large Red lens, 1 large Amber lens, and 2 small Amber lenses. 

I hope I have answered your questions, Brent, and also given you some of the intriguing historical context surrounding the matters you asked about. I have all the papers and articles on the development of lenses and signal colors, in PDF format, should you ever get interested in the subject... but some of them are quite technical. 

-- abram burnett 
a turnip farmer at heart 

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