Jewish World Review Feb. 10, 2004 / 18 Shevat, 5764
Editors of Merriam-Webster's Collegiate
"Turnpike''; "dead reckoning''
S. B., Cambridge, Massachusetts
Dear S. B.:
The modern toll road takes it name from the Middle English word ``turnpike,'' denoting a revolving frame bearing spikes and serving as a barrier. Before ``turnpike'' came to mean ``highway,'' it referred to the gate through which one had to pass to get on a toll road. The tollgate was a post set in the ground with another post or pike attached and extending horizontally. The pike would be positioned across the entrance to the road.
Once the toll was paid, the post would be pivoted, swinging the pike out of the way. Roads with such gates became known as ``turnpike roads,'' and ``turnpike road'' was eventually shortened to ``turnpike'' and ``pike.''
I would like some clarification of the term ``dead reckoning.'' My dictionary says it's ``the method of finding the place of a ship without the aid of celestial observations, from a record of the courses sailed and the distance made on each course.'' The last part in particular seems ambiguous - does ``from a record of the courses sailed'' mean from other ships' experience? Also, I want to use the term figuratively, and I always thought that ``dead'' reckoning implied ``more accurate'' reckoning, but I would think using the stars would be more accurate. Any light you can put on this term and its origins would be greatly appreciated.
L. O., Laredo, Texas
Dear L. O.:
``From a record of the courses sailed'' refers to the careful charting of small sections of a given ship's course. Each plotting is calculated from the ship's previously determined position and takes into account the direction and amount of anticipated progress since that last position.
``Anticipated progress'' is based on speed, of course, but has to be adjusted by estimations of wind and current. Your association of ``dead reckoning'' with accuracy is understandable, since ``dead'' occurs commonly in contexts where it means ``exact,'' as in ``dead center,'' or ``exactly,'' as in ``dead on target.'' But that's not its meaning in ``dead reckoning.'' The longer dead reckoning is used as the exclusive form of navigation during a voyage, the more the unknowns regarding wind and current have the potential to multiply, ultimately resulting in gross errors. This obvious deficiency is why navigators long ago developed methods for using the observance of heavenly bodies to determine a ship's position.
Thus, any figurative sense of ``dead reckoning'' would have to indicate uncertainty. It is ``guesswork'' based on some sort of intelligent computation. Here's an example of figurative use: ``Dead reckoning, based on a collation of names, events, and years, has enabled scholars to put the beginning of the Egyptian Dynastic Period.''
The actual term ``dead reckoning'' only goes back to the early 17th century, though obviously the technique is much older than that. The first known example of its use in print is in a work titled ``A short treatise of magneticall bodies and motions,'' where it occurs in a reference to a ``true'' (presumably one based on celestial observations) as opposed to a ``dead'' reckoning. We don't really know exactly why this method of calculating a ship's position came to be called ``dead reckoning.''
Some people will tell you that the ``dead'' in ``dead reckoning'' is a shortening of ``deduced'' or ``deductive.'' According to this explanation, dead reckoning calculations in a ship's log were at one time entered under the heading ``de'd'' or ``DED,'' the contraction or abbreviation being all there was room for, and eventually the shortened form was modified to ``dead.'' (One version of this explanation has a clueless 18th century skipper inserting the ``a,'' thinking he was correcting a misspelling of ``dead.'') Unfortunately, however, this theory of origin has no factual basis, for there is no actual record of such log entries, and there is no evidence that what we now call dead reckoning was at one time called ``deduced'' reckoning. The fact is that the adjective ``dead'' has had a great variety of senses throughout its history. Its use to denote a type of navigation is most likely an outgrowth of its old sense ``complete, total'' (as in ``dead silence'' and ``dead certainty''), referring as it does to navigation that is entirely based on ``reckoning'' or calculation, without reference to celestial observations.
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