\input amfonts
\setbox1=\hbox{I}
\def\tr#1pt{\varunit #1pt \setbox0=\vbox{
    \parshape 11 0vu0vu -1vu2vu -2vu4vu -3vu6vu -4vu8vu
     -5vu10vu -6vu12vu -7vu14vu -8vu16vu -9vu18vu -10vu20vu
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  \leftskip=0pt plus 1pt minus 1pt \else \rightskip=-1wd1 \fi
    \parfillskip=0pt \noindent
    I turn, in the following treatises, to various uses of those
    triangles whose generator is unity. But I leave out many more
    than I include; it is extraordinary how fertile in properties
    this triangle is. Everyone can try his hand.}
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\def\pub{\box0\the\varunit\vfill\eject}
\scrollmode
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