Uneven line spacing in paragraph

line-spacing

I am in the final stage of polishing my book in LyX. In one paragraph I noticed an uneven line spacing. When I copy the whole paragraph to a different section, the line spacing is evened, even if both paragraphs are set to begin a new page (see the two images in comparison). To match the publisher's requirements, there is single line spacing throughout the document (no setspace). I am happy to give any more details, but I currently have no clue what could cause this. What values should I check?

enter image description here

enter image description here

\baselineskip seems to remain, as it should, constant, as I try to demonstrate with these images:

enter image description here enter image description here

Could the problem be a quote that follows the bugged paragraph?
I redefined quote in the preamble with:

\renewenvironment{quote}{\fontsize{9.8pt}{11.4pt}\selectfont
\list{}{\leftmargin0.5cm
\rightmargin0cm}
\item\relax}
{\endlist}

Best Answer

It looks like you have something equivalent to

enter image description here

Where in the right hand box (like your first image) the normal size text is set on a too-small baseline so the letters are too close together in most lines and accented letters or descenders cause the line spacing to change to avoid over-printing.

\documentclass{article}

\usepackage[T1]{fontenc}

\begin{document}

\parbox[t]{3cm}{
Some German text 
Some German text 
Some german text with  \"U and g
Some German text 
Some German text 
Some German text with  g
Some german text with  \"U and g
}
\quad
\parbox[t]{3cm}{\footnotesize{\normalsize
Some German text 
Some German text 
Some german text with  \"U and g
Some German text 
Some German text 
Some German text with  g
Some german text with  \"U and g}
}
\end{document}

The usual cause is as shown here having a size change command without including the end of paragraph in its scope, that causes the font size to change but the paragraph settings revert at the } so this is setting \normalsize text on a baselin spacing set for \footnotesize.

The above guess was essentially right the exmple finally provided shows the form was

enter image description here

\documentclass{article}

\usepackage[T1]{fontenc}

\newenvironment{oops}{\fontsize{9.8pt}{11.4pt}\selectfont}{}
\begin{document}

\parbox[t]{3cm}{
Some German text 
Some German text 
Some german text with  \"U and g
Some German text 
Some German text 
Some German text with  g
Some german text with  \"U and g
}
\quad
\parbox[t]{3cm}{
Some German text 
Some German text 
Some german text with  \"U and g
Some German text 
Some German text 
Some German text with  g
Some german text with  \"U and g
\begin{oops}
  
\end{oops}
}
\end{document}

Here the second paragraph is using normal size text but does not end until inside the oops enviornment at which point \baselineskip is too small.

The solution is to make sure the paragraph ends before the size change, either by putting \par before it in the definition or (better in your real case) changing the font in the \list setup so the \list handler can take control of he paragraph end.

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