This link gives more details of how the device works.

http://www.anteques.com/srv/antaday/1113.htm

Well, yours is prettier than the ones Anu linked to; that head one creeped me out.
How in the world did anyone ever think up something like this? I also thought it was interesting that Anu credited it to an earl (didn't you all just love his use of early?) as the owner, but the links credited it to the missus.

It took me a while to figure out how the teapot worked. The hole in the bottom must connect only to a tube running through the handle. With the teapot upside down it could be filled with no escape from the spout. When turned back up again, tea could not escape from hole in the bottom, because the handle tube is arched high enough that tea could not re-enter it. I suspect though that it might have been tricky to prevent spill in the filling process when first turned upright again. And the traditional tea ritual would not have been possible.

and the tea would be stewed forever, without recourse to freshening.

and it would be hot-handled.

and it would be clumsily heavier than functionally required.

and it would STILL bloody drip!

Apart from that, another triumph of upper-crust British lunacy - expensive to make, ugly to look at, functionally debased... so ending up highly collectible :)

The hole in the bottom must connect only to a tube running through the handle. With the teapot upside down it could be filled with no escape from the spout.

A sort of a Klein teapot? (explained at http://www.math.rochester.edu/misc/klein-bottle.html, nice photos of actual Klein bottles at http://www.kleinbottle.com -- a commercial site I have no connection to) I assumed that the hole in the bottom was just connected to a long tube that ended near the top of the pot. It would have to be filled at an angle, or a pretty large amount would slosh out when it was turned, but I can envision doing it. Assuming the tea is prepared apart from those to whom it is being served, a little sloshing presents no etiquette problems, but your solution would work much better (aside from the problems Mav mentions).

That cadogan with the human face on the side
would not likely have been suitable for use. The description says it was slip cast. This means that a plaster of Paris mould has a very thick suspension of clay in water poured into it, allowed to stand a short period of time.The plaster of Paris takes enough water out of the supension in contact to increase its viscosity enough that it will be able to keep the shape of the mould when the mould is tipped upside down to pour the still semiliquid
clay suspension out.
That handle is so narrow in cross-section that the tube it contains would be very narrow, and the handle as a whole
quite fragile.
I have done enough slip casting to be quite sure of this.

I once was able to handle one of these pots at a small museum in a Staffordshire pottery and see its use demonstrated. That particular pot was made as Flatlander described, with a tube running vertically up from the bottom, narrowing towards the top. The base of the spout was close to the bottom of the pot. The pot was turned upside down and liquid was poured into the tube, filling the whole pot and the tube up to a mark scratched on the inside of the tube, presumably calculated to avoid getting liquid into the spout or above the top of the tube once the pot was righted. As you turned the pot up the right way the liquid left in the tube dribbled out. There was not much mess, perhaps because the vacuum formed as the pot was righted held back the flow of liquid to a trickle. I think wwh's idea of a tube running up the handle would have been even less messy and perhaps some were made in that way; in my youth, many teapots had handles too hot to hold (try a silver teapot as an example!), so I don't think that would have been seen as a big disadvantage - anyway, what were servants for?

To me the strangest thing about the whole idea is that as there was no way of inserting tea leaves into the Cadogan pot, or extracting them afterwards, the tea would have had to be brewed in a separate pot and then poured into the Cadogan – you might as well have poured the tea in through the spout! By the time it was served to eager drinkers it would have been pretty cold. The usual recommendation when making tea is to rinse the pot with hot water to warm it before making the tea. I guess you could do that with the Cadogan, but probably it was just intended to be a drawing room demonstration of a simple but intriguing scientific principle rather than a serious teapot!

After thinking about it some more, I can now see idea of tube running through the handle was wrong.The bottom of the pot could have been an upside down funnel, with straight tube extending almost to the top. The funnel could have been slip cast separately, and then put in place with glaze to seal the joint on firing. It would have been impossible to wash inside adequately, so residues could spoil flavor. Yuk.

Another collectible that is as rare as you'd think is the Medieval dribble cup. If you knew where to put your finger and/or tongue on the little hole(s) to create a vacuum inside you could drink safely. Your guests however wouldn't know the trick.

Just the thing for one of Betty's garden parties!

Did anyone imagine a teapot in a sweater? I know the spelling's off, but did anyone else imagine this?

Did anyone imagine a teapot in a sweater?

That would be a tea cosy, I guess.

http://www.knitting-and.com/knitting/patterns/teacosies/cable-teacosy.htm

I think they prefer pullovers although a cardy would suit that plump little shape.
OK knitters, your assignment should you choose to accept it is to design a tea cosy that looks like a cardigan, complete with buttons. Could be very cute.

is this a sponsered contest i can post to my knitting boards, Zed? last year, there was an exhibtions (it travel through a bit of US and Canada of hand knit TP covers.. the winning entry was shaped like a throne..(how appropiate for the throne room!)

so what are the rules? do we need to send you the actually cardagen tea cosys? or just pictures of them? do we need to provide written instructions for reproducing them? or just a sample? who get to keep the copyright on the directions?..

come on then details! (i have knit a tea cosy or two.. mostly simple functional ones.. (with the spout and handle exposed so you could pour without removing the cosy.)

personally i think tea is vile, but i do have the stuff, and tea pots for guests.

I used to love hot tea when I was in my twenties and Earl Grey was my favorite. And now I, too, of troy find it, as you put it, 'vile.'

And just for the record and a matter of interest for those who like knowing the differences in spelling:

tea cosy had 4 direct hits on onelook.com
and tea cozy (how I would have spelled it) had 7 direct hits

I agree that Earl Gray tea IS absolutely vile. Almost as bad as a tisane. In England, fortunately, you will only be served it if you ask specifically for it. Normally we drink fairly strong English breakfast tea, as it is known to all USns. Assam is good too, as are many other Indian and Chinese teas. Lapsang Souchong has an interesting smoky, tarry flavour that is OK for a change now and then.

Lapsang Souchong has an interesting smoky, tarry flavour

that taste as if you are drinking the hot water run off from a newly paved macadam street...yeah, that's about right... well the run off might taste a little better..but.

plain oolong tea (as commonly served in chinese restaurants in NYC) is drinkable in the small quanities a chinese tea cup holds. but i don't eat out (chinese food) that often.

Run-off, of troy! Ha!

I don't know whether it is because I am in (most likely) my last couple of decades, but, as so often seems to be the case with many my age, we start looking at our horrible collection of bad health habits and try to begin undoing a little of the damage to prolong this ecstatic luxury called life. Anyhow, I do drink coffee and have tried cutting back--and successfully.

However, of troy, we really should try switching to hot tea because of all the health benefits in tea. I believe there are nutrients in tea not found in coffee. Magnesium seems to ring a bell from those days that I did drink hot tea. Not that you're in my age bracket yet, but perhaps we should give hot tea another try, road run-off or not! (Of course, you were writing about the smoky tea and not tea in general. Personally, hot tea leaves a kind of coarse film on the enamel, or so I've speculated.)

Not my porcelain drinking vessel of herbaceously infused water. (Your mileage may vary.)

I find badly brewed tea and coffee both vile. The problem with Earl Grey and most "flavored" teas (like jasmine) is that such a low quality of tea leaf is used to flavor. (And don't get me started on "flavored" coffees.) Most tea comes from the same kind of tea leaf, it's the fermentation process that determines if it's going to be green or smokey, etc. I particularly like Pu'Er tea.

http://en.wikipedia.org/wiki/Tea