[texhax] Controlling line spacing in footnotes with plain TeX

[D. R. Evans]

I have the following definition of \footnote:

----

\def\footnote#1{\let\atsf=\empty %
  \ifhmode\edef\atsf{\spacefactor=\the\spacefactor}\/\fi
  \raise 0ex \hbox{#1}\atsf\vfootnote{#1}}

----

and the following definition of \vfootnote:

----

\def\vfootnote#1{\insert\footins\bgroup
  \interlinepenalty=\interfootnotelinepenalty
  \splittopskip=\ht\strutbox
  \splitmaxdepth=\dp\strutbox \floatingpenalty=20000
  \leftskip=0pt \rightskip=0pt \spaceskip=0pt \xspaceskip=0pt
  \baselineskip=XXX (see below)
  \rmfnote
  \textindent{#1}\footstrut\futurelet\next\foatt}

----

Outside of the footnote, \baselineskip is set to 13.5pt ± 0.5pt. But I want
it to be smaller in the footnote. But I don't understand what is happening
as I try various values for XXX in the above code.

I am trying to typeset a three-line footnote.

1. If I omit the line containing XXX, the footnote is typeset with the same
line spacing as the main text, which is what I would expect.

2. However, if I set it to (say) 10pt, the distance between the first pair
of lines in the footnote is visibly less than the distance between the
second pair.

After reviewing page 78 of the TeXbook, I tried the following in place of
the line containing XXX above:

----

  \baselineskip=10pt
  \lineskip=10pt

----

But that just made things worse (for reasons I don't understand at all).
Now  the distance between lines 1 and 2 of the footnote looks reasonable,
but the distance between lines 2 and 3 is huge.

Can someone explain what I need to do to set the lines of the footnote so
that have a consistent separation?

  Doc

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