new question (Brent Greer's Questions on Markers)

NW Mailing List nw-mailing-list at
Tue Feb 23 14:58:56 EST 2016

wow, awesome history lesson. Thanks

Mike Weeks, Seattle

On Tue, Feb 23, 2016 at 8:04 AM, NW Mailing List <nw-mailing-list at>

> 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 i
>  llumination 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 publishe
>  d 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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