This is an upper case U? Where was it published? I have looked through my book with Art Nouveau-era typefaces and didn't see anything like it.

- Mike Yanega

Hi Mike. This is an upper case U, it was used (overturned)
as notation for a logical function by Frege in Grundgesetze
der Arithmetik.

Another question, or two -- was this a monogram? Is this the only letter you have?

- Mike Yanega

Mike, I've no idea of its origin at all -- and there are no
other similar letters in the book.

" This is an upper case U, it was used (overturned)
as notation for a logical function by Frege in Grundgesetze
der Arithmetik."

By 'overturned', you mean upside-down, like an Intersection function(?), as opposed to a Union function?

- Mike Yanega

double post, sorry

ChrisL

It looks to me like a lowercase u with an ornament that might make it to be used only at the end of a line? Sort of "u swash" flourish?

ChrisL

Yes, it was used upside down (rotated 180 degrees), with the
upper left beak looking like a right serif on the right
foot. As used, the feet descended, but the bowl reached only
to x-height. It may have been a lower-case letter at a larger
point-size, but my guess is that it's a capital.

When I invert the image it looks like an N. Upper case N's in some 19th century typefaces did look like large cursive/italic n's. I did find one typeface with a recurved swash on an N, but it didn't go through the letter like this. I didn't find any U's that were like it at all.

- Mike Yanega

The typeface was called 'Inserat-Kursiv' and Gert Wiescher has digitized it as Grocers Script. Have a look at the N.

- Mike Yanega

Thanks Mike -- this is certainly the closest thing to it that I've
seen. Would you have a reference to "Inserat-Kursiv"? I couldn't
find one on the page you linked to, nor google.

Thanks again

I found the typeface shown in the Dover book by Ludwig Petzendorfer called "Treasury of Authentic Art Nouveau Alphabets" on Plate 55. It says the foundry was 'Aktiengesellschaft Für Schriftgiesserei und Maschinenbau - Offenbach' [Germany]

- Mike Yanega

It could be a "script" letter.

In Mathematics, script letters have particular meanings, like script L for Laplace transform or script H for Hamiltonian operator. See http://www.unicode.org/charts/PDF/U2100.pdf for some examples. I couldn't find any script N, though.

This U is not a letter per se but a german abbreviation for pound. it's form is derived from lb (the abbrebiation of librum (latin for pound)).
as in Germany the non-metric units were banned in the 70's you can find this sign no more.
but I remember it well fom my school days.

Wolfgang, did you look at the 'para.jpg' image that was posted? It seems more like an N than a U, doesn't it?

- Mike Yanega

Mike, I did look at the 'para.jpg'. To me it is obvious, that thy glyph was set upside down. There are different forms of the 'pound sign'; the most common form is shown in the pic below.

Thanks Wolfgang. Obviously I am out of my element now. Why was it turned upside-down? (I guess that doesn't matter. I can see that it does seem to be like that mark.)

We still don't have a clue what typeface it's from, and it's less likely that samples will show the 'lb' character unless someone has some very old type speciment books from Germany.

- Mike Yanega

this looks like an antiquated version of the "pound" sign. unicode ID # 2114.
also known as the "number sign". as in #. follow its etymology here:

http://www.answers.com/topic/number-sign

http://www.unicode.org/charts/PDF/U2100.pdf

The trick is that it is neither an n or a u but an L and a b ligated.

ChrisL

As soon as you say it is an lb ligature suddenly it leaps
out at me. I had thought it overturned because as an N it
has a peculiar one-sided serif on the right foot, this
looked more natural to me as the left beak of a U.

Frege used overturned characters extensively. There are
overturned f's and d's with hooks attached, e's and c's with
a kind of spur on top, and an overturned A denoting the
paradoxical Russell set -- the set of all sets which are
not members of themselves.

Thanks everyone for the comments.

This sign was not part of an ordinary typefont. In the times of lead type you had to buy mathematical, currency and other signs either single or in small sets. I found the sample below in a specimen book of a printing shop from 1933. I'll try to find a sample from a specimen by a foundry.

"this looks like an antiquated version of the “pound” sign. unicode ID # 2114. also known as the “number sign”. as in #."
Ch, This symbol is actually called an Octothorp, otherwise known as the numeral sign. It has also been used as a symbol for the pound avoirdupois but this usage is now considered archaic. It's name derives from its cartographic use as the symbol for a village (eight fields surrounding a square) as it literally means 'eight fields'.