Ruling a page before you write on it
A scribe ruled the page before writing a word, and the ruling was arithmetic: nib widths in, line height out. Every margin on this site comes from the same calculation, done by a stylesheet instead of a lead point.
Every formal hand is ruled before a single letter is written, and the ruling is not a matter of taste. It is derived from the nib, because the nib is the only fixed quantity on the desk.
The unit is the nib width
Lay the pen flat on the page and step it, corner over corner, up the sheet. Each step is one nib width, and every vertical measurement in the hand is a count of them. The x-height of a foundational hand is four nib widths; an uncial is about three and a half; a chancery italic is five.
That is why the same hand written with a wider nib is not just larger — it is identically proportioned, which is a stronger guarantee than any point size gives you.
The arithmetic
For a nib of width and a hand whose x-height is nib widths, with ascenders and descenders each nib widths beyond it, the line height needs
where is the gap you leave between the descenders of one line and the ascenders of the next. Set and the lines interlock — legible, and used deliberately in some manuscript hands, but not what a beginner is aiming for.
| Hand | x-height () | Extenders () | Line height at |
|---|---|---|---|
| Foundational | 4 | 3 | 20 mm + gap |
| Uncial | 3.5 | 1 | 11 mm + gap |
| Chancery italic | 5 | 4 | 26 mm + gap |
| Gothic textura | 5 | 2 | 18 mm + gap |
Why the gap is the interesting number
Because it is the only free variable, and it is the one that decides whether a page reads as dense or as airy. Everything else is dictated by the nib. A scribe changing the feel of a page is almost always changing and nothing else — which is the same move as changing the leading and leaving the type size alone.
Rule in pencil, and rule the verticals too
Two vertical lines for the text block's edges, and one more a nib width outside the left one, because ascenders and capitals overhang and a hard left edge on every line looks mechanical. Then erase nothing. A ruled line still faintly visible under the writing is what a manuscript page is supposed to look like.