Design question re: tiled station names

From a designer's point of view, I can only assume it is something to do with the way the type is spaced (it's all to do with what we call kerning). Aesthetically, reading the text doesn't seem as clear without the dots because it's kerned quite tightly with those particular station names as there's more letters to fit in the same sort of space (and I suppose, from a smaller train window, particularly on older stocks, you only perhaps catch some of the station name initially).

Looking at pictures of the tiling arrangements (in Douglas Rose' 'Tiles of the Unexpected'), it may also be something to do with the way the tiles have been fired. With Holloway Road, the dots seem to take place in the middle of the tile. With Caledonian Road, the way the type has been kerned means that to have double dots would mean the dots would have to be split across the joints of two consecutive tiles (something which would be a bit of a problem perhaps aesthetically, as they wouldn't quite be equal semi-circles considering the finished result after grouting). Based on what I can see to be the x-height (the invisible line that would be formed based on the height of lowercase letters without ascenders or descenders) of Caledonian Road, it probably would've been easier to have just a dot.

Click here to see York Road here with the double dots (on Douglas Rose's site), and click here to see Regents Park with the single dot. I've not seen anything in his book regarding this, but then I haven't flicked through the book in a while. Not sure whether all dots follow the same trend, the majority in the book do.

AGOG!!!

You've never even glanced at a copy of Tiles of the Unexpected before???

You can borrow mine if you like.

(Apols for tweeting this reply earlier by mistake - [cough] senior-ish moment)

I've seen it up on a high shelf, giggled at the title and never picked it up. Now I know what' in it I'm going to start writing my Christmas list!

I'm not sure that there is a definitive answer to the OP's question. It's not really covered in Doug Rose's book, and there appears to be no real consistency in whether a single or double dot was used. The kerning does not seem to affect it, and there are examples of dots split across adjacent tiles, so although 3.1's theory is nice, I don't think that it is the answer.

It's also interesting that most stations with more than one word in their name have the dots between the words that make up the name (but not KINGS CROSS or OXFORD STREET, which do have dots either end). Rather more stations with two- or three-word names have dots between the words but not at each end. There are no stations that mix single and double dots.

Just a few random observations on this topic...