Help required with brass TT&H lens

[Pete Watkins]

I'm trying to find out more about an f8-f90 Taylor,Taylor & Hobson lens that I have. It is engraved Taylor, Taylor & Hobson (no mention of Cooke anywhere on the lens) Leicester on one side. On the other side of the lens (the laquer is breaking down a bit around the engraved parts and it's not too easy to read) is 15x12 ERR. Below this is EQ FOC 24ins and below that is the lens number 4327 or 4527.
I've checked the Vade Macum and ERR does not appear. Assuming that the RR bit stands for rapid rectilinear I can't work out what the "E" is all about.
The lens appears to give a wide angle view (to my eyes anyway).
The lens has a diaphram and as there is no mention of Cooke I am assuming that the lens is before 1885.
Can anybody add to this information please?
Pete.

[goamules]

Some RRs and Petzvals, especially over on your side of the pond, were rated "rapid" or "extra rapid". But I think extra rapid for a RR would be f6 or so....Does it indeed read f8?

[Pete Watkins]

Thanks for looking goamules, it does read f8 but the "extra rapid" theory makes sense. The lens is about 7 inches high and the front and rear glasses are about 3 inches in diameter.
Thanks again,
Pete

[goamules]

It should be a dandy lens. I have a lens about that size engraved; Extra Rapid Rectilinear - The Robert Dempster Co. and it's an f6. You'll probably like the TTH a lot.

[Ernest Purdum]

Since the lens is a 15 X 12, f8 would have been still quite rapid at the time.

I think TT&H would not have marked a Rapid Rectilinear with the Cooke name. The diaphragm suggests (to me, at least) somewhat later manufacture.

How about asking the Cooke people? They do, I think have some old records.

[Pete Watkins]

Thanks to goamules and Ernest. I'll try TT&H in Leicester. Ernest the lens number is in the 4xxx's and according to The Lens Collectors Vade Mecum TT&H offered diaphrams as optional extras in the days when Waterhouse stops were the norm.
Best wishes,
Pete