OED and definition of "siphon"

Robin Hamilton robin.hamilton2 at BTINTERNET.COM
Wed May 12 16:10:43 UTC 2010

From: "Dan Goncharoff" <thegonch at GMAIL.COM>
> Maybe they are both right:
> http://www.straightdope.com/columns/read/2372/how-does-a-siphon-work
> DanG

This came up independently on another list (in the wake of a singularly
venomous discussion of the correctness of the OED definition of "jump-cut").
I'll append the final post, which included most of the relevant
pre-discussion, in case anyone is interested.  (One listmember provided a
pretty detailed explanation of the science behind the issue.)


----- Original Message -----
From: "Robin Hamilton" <robin.hamilton2 at BTINTERNET.COM>
Sent: Tuesday, May 11, 2010 2:31 PM
Subject: Re: A man with a mission

More lexicographical geekery (you have been warned).

From: "Alison Croggon"

I'd be inclined to trust the physicist.

I wouldn't trust my grandmother to teach me how to suck eggs, in this
particular area.  Skepticism comes with the territory.

I'd have more faith in the inestimable scientist interviewed by the Brisbane
Times, if it didn't turn out that what he's saying, both with regard to the
gravity/atmosphere confusion and its place in reference works, hadn't
*already been pointed out.  Admittedly, in that somewhat obscure source, the
Encyclopaedia Britannica:

from the Encyclopædia Britannica:
also spelled syphon

... instrument, usually in the form of a tube bent to form two legs of
unequal length, for conveying liquid over the edge of a vessel and
delivering it at a lower level. Siphons may be of any size. The action
depends upon the influence of gravity (not, as sometimes thought, on the
difference in atmospheric pressure; a siphon will work in a vacuum) and upon
the cohesive forces that prevent the columns of liquid in the legs of the
siphon from breaking under their own weight.


... so his triumphant discovery apparently isn't exactly news, as we have
there not just the "gravity, not atmosphere" point but also that this is a
'mistake' frequently made in reference works -- "as sometimes thought".
(What happened to journalists supposedly having been trained in
fact-checking?  <g>)

Also, of course, the Oxford editorial board were *already onto the case.

_The New Oxford Dictionary of English_ (my copy to hand is the 1998
printing), which is to a degree independent of the OED (it's not simply a
Concise or Shorter version, but an independent text) makes a significant
change from the definition found in the OED itself:

 SIPHON:  a tube used to convey liquid upwards from a container and then
down to a lower level by gravity.  Once the liquid has been forced into the
tube, typically by suction, atmospheric pressure on the remainder in the
container maintains the flow.

So, yes, the current entry in the OED is misleading, if not indeed wrong,
and hasn't yet been revised (the committee, according to the good Doctor
Hughes, has only just finished the letter "R") but Merriam-Webster Online
and the NODE both provide a differently-slanted definition.

Both, however, *retain a reference to "atmosphere".

I'd be very much surprised if in both cases (M-W Online and NODE), the
editorial committees were ignorant of the Encyclopædia Britannica -- for
god's sake, it must be the *first place (if certainly not the Final Truth)
where a dictionary editor would go if he or she were trying to confirm or
correct the scientific accuracy of a definition in a dictionary that they
were in the process of revising.

Except that they both retain the reference to atmosphere, though admittedly
in a different form than that found in the OED2.

Curious, that.  Maybe it's not something as simple as the gravity/atmosphere
confusion that Dr. Hughes was suggesting.

(At this point, I pass the ball back to Uche, as to whether and to what
degree the current dictionary entries are scientifically incorrect or

If I were guessing at a subtext to this narrative, it would run as follows:

Dr. Hughes writes to the OED Revision committee drawing their attention to a
flaw in the current OED definition of "siphon".

The OED glumly says to one of its understrappers, "Oh god, someone *else has
noticed this -- send him a copy of Letter #169, "Dear [Mr Mrs Mz Doctor
Honourable], thank you for drawing our attention to this.  We will take your
observation into account."

Dr. Hughes gets his ten minutes of fame in the Brisbane Times, who in turn
get a quick article out of the business (and don't even have to do any
work -- they do quote the OED2 entry correctly, but I bet Dr. Hughes
supplied them with that.)

Alison gets to triumphantly draw attention to The Failings of the OED.

... and I get a chance to pontificate yet once more.

If you think about it, it's pretty much one of those rare no-lose


siphon, n. SECOND EDITION 1989

    1. A pipe or tube of glass, metal, or other material, bent so that one
leg is longer than the other, and used for drawing off liquids by means of
atmospheric pressure, which forces the liquid up the shorter leg and over
the bend in the pipe.
Merriam-Webster Online

1 a : a tube bent to form two legs of unequal length by which a liquid can
be transferred to a lower level over an intermediate elevation by the
pressure of the atmosphere in forcing the liquid up the shorter branch of
the tube immersed in it while the excess of weight of the liquid in the
longer branch when once filled causes a continuous flow ...

On Tue, May 11, 2010 at 11:33 AM, Uche Ogbuji wrote:

> On Mon, May 10, 2010 at 6:38 PM, Robin Hamilton wrote:
>> Neatly spotted, Alison!
>> He's right that the OED isn't quite correct here, but his suggestion that
>> it's all gravity is possibly equally misguided.
> I had to take fluid mechanics in various forms in Engineering school, and
> this stuff is still rather brain-bending, but I according to my memories,
> he
> is right. Atmospheric pressure is essentially equal on the surface of the
> reservoir fluid and on the exposed surface of the end of the siphon. There
> is infinitesimally more pressure on the latter because it is
> infinitesimally
> closer to the Earth's center of mass, but that effect is overwhelmed by
> the
> pressure exerted by gravity, which is hydrostatic pressure within the
> fluid
> itself, and not imparted by the surrounding fluid (the atmosphere).
> For purposes of a dictionary entry it makes sense to just leave it at
> "gravity", but at the same time, I like your suggestion of
> "by means of hydrostatic pressure"
> Considering that hydrostatic pressure is nothing but pressure developed by
> the nature of a fluid in a force field (i.e. gravity). Anyone who takes
> that entry as a clue to revise their fluid dynamics will quickly remember
> that the relevant hydrostatic pressure comes from the siphoned fluid
> itself,
> and not from the atmosphere, so all would be well.

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