Dead Reckoning, with the 'a'

Corky Scott wrote:

The folk etymology from deduced is not documented in the OED or any
other historical dictionary. Dead reckoning is navigation without
stellar observation. With stellar observation, you are "live", working
with the stars and the movement of the planet. With logs, compasses,
clocks, but no sky, you are working "dead".

Thanks for looking that up, Corky. Another explanation I've heard is
reckoning against something dead in the water (i.e. not under sail), but
that doesn't sound entirely convincing either. I wonder if it has any
relationship to the phrase "dead ahead".


All the best,


David

Gary Drescher wrote:

Yup. Also, "deduced reckoning" would be redundant, as reckoning is
inherently deductive.

The Count on Sesame Street can reckon inductively: "one, two, three, THREE
COOKIES!!! BWAAA HAAA HAA!!!"


All the best,


David

Yup. Also, "deduced reckoning" would be redundant, as reckoning is
inherently deductive.

"Deduction" means going from the universal to the particular, as in
the classic example used in logic textbooks:

All men are mortal. Socrates is a man. Ergo, Socrates is mortal.

INduction is the process of drawing inferences from PARTICULAR
OBSERVATIONS, as in::

Socrates died. Aristotle died. Ptolemy died. Ergo, all men die.

Dead reckoning starts with "inputting" particulars--the airspeed of MY
airplane, the heading I AM going to fly TODAY, the CURRENT wind, and
therefore, it is an example of induction, not deduction.

Science is an inductive process. Statistics is inductive. Philososphy
and theology are deductive.

I suspect, but without any supporting evidence, that "dead" reckoning
comes from the use of "dead' in phrases such as "Dead right." "Dead
on." "Dead center." Meaning, "exact."

Dead reckoning is EXACT in that, provided the INPUTS are correct, the
results will be EXACTLY right.

That, BTW, is the case with all inductive processes. As the saying
goes, garbage in, garbage out.

If the winds are not as forecast, if you don't hold the heading
precisely, the results will be erroneous. But that is not a f ault of
the dead reckoning process.

vince norris

Just as a dictionary tells us how a word is used by "ordinary" people, it also offers
information as to how a word might have been used by "ordinary" people to
coin a new word or phrase.

I was trying to say that the term "dead reckoning" was coined not by
"ordinary people" but by specialists-- people who had a classical
education, and knew the meanings of "deduction" and "induction."

If you disagree, that's fine.

While it's my opinion that the word "deduced" has nothing to do with the
derivation of "dead reckoning".....

We agree on that.

vince norris

I hate to confuse anyone with the facts but the Oxford English Dictionary
2nd ed. has the following entry

dead reckoning

[dead /a./ V.]

The estimation of a ship's position from the distance run by the log
and the courses steered by the compass, with corrections for current,
leeway, etc., but without astronomical observations. Hence /dead/
latitude (q.v.), that computed by dead reckoning.

"*1613* M. Ridley /Magn. Bodies/ 147 Keeping a true, not a dead
reckoning of his course." "*1760* Pemberton in /Phil. Trans./ LI. 911
The latitude exhibited by the dead reckoning of the ship." "*1840* R.
H. Dana /Bef. Mast/ xxxii. 124 We had drifted too much to allow of our
dead reckoning being anywhere near the mark." "*1891* /Nature/ 3 Sept.,
The log, which for the first time enabled the mariner to carry out his
dead-reckoning with confidence, is first described in Bourne's ?Regiment
for the Sea?, which was published in 1577." "*1917* Bosanquet &
Campbell /Navigation for Aerial Navigators/ i. 4 In aerial
navigation+Dead Reckoning is the position arrived at as calculated from
the estimated track and the estimated speed made good over the
ground." "/Ibid./ 5 These data enable us to find a Dead Reckoning
position." "*1935* C. G. Burge /Compl. Bk. Aviation/ 477/1 Dead
reckoning+is a compromise between pilotage and navigation." "*1868*
Lowell /Witchcraft/ Prose Wks. 1890 II. 372 The mind, when it sails by
dead reckoning+will sometimes bring up in strange latitudes."


The log is the ships log - not a log in the water.

It is interesting to note the distinction between pilotage, navigation and
dead reckoning.

"vincent p. norris" wrote in message
...
Yup. Also, "deduced reckoning" would be redundant, as reckoning is
inherently deductive.

"Deduction" means going from the universal to the particular, as in
the classic example used in logic textbooks:

All men are mortal. Socrates is a man. Ergo, Socrates is mortal.

INduction is the process of drawing inferences from PARTICULAR
OBSERVATIONS, as in::

Socrates died. Aristotle died. Ptolemy died. Ergo, all men die.

Dead reckoning starts with "inputting" particulars--the airspeed of MY
airplane, the heading I AM going to fly TODAY, the CURRENT wind, and
therefore, it is an example of induction, not deduction.

Reasoning from the general to the particular, as in the syllogism you cited,
is one of the earliest and simplest kinds of deduction to have been
formalized. But any chain of reasoning that follows by necessity from
general axioms constitutes deduction. Hence, deduction includes, for
example, calculating that 2+2=4 (because that equation follows from the
axioms of arithmetic, even though the equation addresses particular
parameters). Similarly, it is deductive to reason from the axioms of
Euclidean geometry that if I start at position x,y and travel in direction
theta for t minutes at v knots, then I am at position x',y'.

Induction, by contrast, involves a supposition that new instances will
continue to resemble old instances (as in your example above), even though
the contrary is logically possible. (To confuse matters, what's known as
"mathematical induction" is actually a form of deduction.)

Science is an inductive process. Statistics is inductive. Philososphy
and theology are deductive.

Science and philosophy make extensive use of both inductive and deductive
reasoning. Mathematics is purely deductive. Statistics, as a branch of
mathematics, is deductive, but using statistical reasoning to make
predictions involves an inductive leap within deduced constraints.

--Gary

"Daniel L. Lieberman" wrote:

The estimation of a ship's position from the distance run by the log
and the courses steered by the compass, with corrections for current,
leeway, etc., but without astronomical observations. Hence /dead/
latitude (q.v.), that computed by dead reckoning.

The log is the ships log - not a log in the water.

I suspect in this definition, they do mean a log in the water, in the
form of a nautical log, which measured distance by counting knots or
revolutions.

http://91.1911encyclopedia.org/L/LO/LOG.htm

On Tue, 10 Aug 2004 12:35:57 GMT, "Daniel L. Lieberman"
wrote:

The log is the ships log - not a log in the water.

Actually not. The log referred to was the object (originally rather
like a log) thrown over the stern. It was attached to a string which
had knots in it, and however many knots passed through the navigator's
fingers in a given period of time measured the ship's speed.

Thus log -- and thus knots.

It enabled dead reckoning because it enabled the navigator to know the
ship's speed more or less accurately.

all the best -- Dan Ford
email: (put Cubdriver in subject line)

The Warbird's Forum www.warbirdforum.com
Expedition sailboat charters www.expeditionsail.com

On Wed, 11 Aug 2004 06:53:09 -0400, Cub Driver
wrote:

On Tue, 10 Aug 2004 12:35:57 GMT, "Daniel L. Lieberman"
wrote:

The log is the ships log - not a log in the water.

Actually not. The log referred to was the object (originally rather
like a log) thrown over the stern. It was attached to a string which
had knots in it, and however many knots passed through the navigator's
fingers in a given period of time measured the ship's speed.

Thus log -- and thus knots.

It enabled dead reckoning because it enabled the navigator to know the
ship's speed more or less accurately.

Exactly--I think you've hit the nail on the head. More details
from http://dictionary.reference.com/search?q=log%20board
show how the name of the book got derived from the log thrown
overboard to calculate a ship's speed. I imagine that our "logging
in" and "logging out" of computer systems is derived in turn from
the ship's log book.

2. [Prob. the same word as in sense 1; cf. LG. log, lock, Dan. log,
Sw. logg.] (Naut.) An apparatus for measuring the rate of a ship's
motion through the water.

Note: The common log consists of the log-chip, or logship, often
exclusively called the log, and the log line, the former being
commonly a thin wooden quadrant of five or six inches radius, loaded
with lead on the arc to make it float with the point up. It is
attached to the log line by cords from each corner. This line is
divided into equal spaces, called knots, each bearing the same
proportion to a mile that half a minute does to an hour. The line is
wound on a reel which is so held as to let it run off freely. When the
log is thrown, the log-chip is kept by the water from being drawn
forward, and the speed of the ship is shown by the number of knots run
out in half a minute. There are improved logs, consisting of a piece
of mechanism which, being towed astern, shows the distance actually
gone through by the ship, by means of the revolutions of a fly, which
are registered on a dial plate.

3. Hence: The record of the rate of ship's speed or of her daily
progress; also, the full nautical record of a ship's cruise or voyage;
a log slate; a log book.

4. A record and tabulated statement of the work done by an engine, as
of a steamship, of the coal consumed, and of other items relating to
the performance of machinery during a given time.
....
Log board (Naut.), a board consisting of two parts shutting together
like a book, with columns in which are entered the direction of the
wind, course of the ship, etc., during each hour of the day and night.
These entries are transferred to the log book. A folding slate is now
used instead.

Log book, or Logbook (Naut.), a book in which is entered the daily
progress of a ship at sea, as indicated by the log, with notes on the
weather and incidents of the voyage; the contents of the log board.

+++++++++++++++++++++++++++++++++++

19th century log-chip:
http://www.nmsi.ac.uk/piclib/imagerecord.asp?id=10284362

+++++++++++++++++++++++++++++++++++

Marty