Re: http://www.straightdope.com/mailbag/mdeadreckoning.html
I totally agree with this article. I’ve researched this topic quite a bit myself, and the author nailed every item. Especially that the “deduced” theory only appeared this century.
I’ve collected hundreds of air navigation texts dating back to 1910, and a big clue is that the idea that the origin was “deduced reckoning” does not appear until 1931. This bogus etymology became popular through World War II, went way, and then came back fairly recently.
1930 was also the beginning of a short period when air navigation authors tried to use “avigation” to differentiate the techniques from marine navigation.
I get the feeling that it was thought that pilots wouldn’t like “dead”, so the “ded=deduced” concept was invented to make flight trainees happier.
Best,
Kevin Darling
Welcome to the Straight Dope Message Board, kdarling, glad to have you with us. And if you’ve been researching word origins, we’re doubly glad to have you with us, and hope you’ll be actively involved!
Thanks for the welcome!
Actually, I’m not even an amateur etymologist. But I used to be smug and “correct” people by repeating the belief that “dead reckoning” was derived from “ded = deduced”.
However, I’m very interested in the history of manual (slide rule type) flight computers. In the course of research, I slowly came to the realization that “deduced” was indeed a recent thing.
Now, Bowditch back in 188x did say that dead reckoning was the art of deducing one’s position. But that’s quite different from point blank saying the words were related somehow. I believe that’s where some of the confusion came from.
Best regards,
Kev
Welcome to the SDMB, Kevin. And thanks for the encouraging words.
I’m curious about your dating of the “deduced” theory to 1931. What publication was this in? If you can give me the details, I can have the report updated. The earliest use I could find was from 1944 (in Marine and Air Navigation by by John Q. Stewart and Newton L. Pierce).
Okay, here is some more information:
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I can’t find reference to “deduced reckoning” in foreign languages. Most either use “estimated reckoning” (a far better term!) or bluntly use their version of “dead”.
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A later (1967 ?? not sure) edition of Bowditch says, in an apparent attempt to back out of any previous correlation between “dead” and “ded.”:
“The expression “dead reckoning” probably originated from use of the Dutchman’s log a buoyant object thrown overboard, to determine the speed of the vessel relative to the object, which was assumed to be dead in the water. Apparently, the expression deduced reckoning was used when allowance was made for current and wind. It was often shortened to ded reckoning and the similarity of this expression to dead reckoning was undoubtedly the source of the confusion that is still associated with these expressions.”
- I simply haven’t found any book, marine or air, that states the “deduced” theory prior to 1931.
The first instance I see of it was in “Avigation”, Jones, 1931. He simply put “dead reckoning (derived from deduced)” in one sentence. This was a time when air navigators were trying to differentiate themselves from marine. An attempt to use “Avigation” instead of “navigation” started in 1929 or so but died out by 1937. It’s very likely that “deduced” was a similar attempt to separate air navigation from marine, with the implication that sailors were too dumb to spell. My guess is that the sailors jumped on this new “ded” bandwagon to show they too were smart.
Note that all other avigation texts before this used “dead reckoning”. Most importantly, P.V.H. Weems, who is called by many “The Grand Old Man of Navigation” (he wrote many marine and air texts between 1930 and the 1960s) always used “dead reckoning”. He was not one to be fooled by upstart ivory tower writers.
- Your original reply included the common OED 1613 reference. What is missing is that I believe the 1613 reference was to a compilation of ship’s logs, one of which logs dates back to 1580 and says in part:
“And in keeping your dead reckoning, it is necessary that you doe note at the ende of every foure glasses what way the shippe hath made (by your best proofes, to be used) and howe her way hath beene through the water, considering withall for the sagge of the sea, to leewards, accordingly as you shall find it growe.”
Even though most of the English used is very old, note that there was no misspelling of “dead”. I have also seen reference to “deade reckoning” from around the same period. No “deduced” though.
You can use any of this without attribution to me, of course. Your original article is excellent.
Best regards,
Kev
This is the most excellent “boards debut” I’ve seen in more than a year. Kev, keep up the good work.
Thanks kindly ChiefScott!
But I feel that my writing has deteriorated since most is done with my baby girl in my lap helping me <grin>. For instance, I left out at least one reference.
The 1580 captain’s log reference I quoted came from Hakluyt (usually the OED reference) and was quoted in, of all places, Wimperis’ seminal 1920 “Primer of Air Navigation”.
On that topic, we should also remember that ignorant sailors likely did not have access to writing in a ship’s log. Probably only the captain and/or navigator would. This doesn’t mean that someone in that position might not have accidentally used “ded” instead of “dead”, but that’s quite different from assuming “dead” came from “ded.” or that others would magically begin using the incorrect spelling!
Best regards,
Kevin Darling
One more thing: I have to say how grateful I am that this staff report was done. It was pointed out by someone in one of the usenet pilot groups, and has gone a long way towards helping to stop the “ded” heads.
At the same time, I think the report should downplay the idea that most pilots agree with the deduced theory. I would say that most believe in “dead reckoning”. It’s the newer pilots (air and sea) trained by newer manuals that are usually the (incorrect) vocal minority.
Thanks again for a great report!
Kev
Something else just came to me:
People’s main claim is that “deduced reckoning” was shortened to “ded reckoning” which sounded like “dead reckoning”.
Only English would have the “ded=dead” sound alike.
Therefore other languages without that handicap should still use “deduced”, but they don’t.
I followed the original discussion on this topic, but didn’t see your wonderful update posts until today. Nice job kdarling.