Side view depiction of a <a href="https://en.wikipedia.org/wiki/Norris_Locomotive_Works" class="extiw" title="w:Norris Locomotive Works">Norris</a> <a href="https://en.wikipedia.org/wiki/4-2-0" class="extiw" title="w:4-2-0">4-2-0</a> locomotive of 1840.
Angus Sinclair
Angus Sinclair, <a rel="nofollow" class="external text" href="https://archive.org/details/developmentofloc00sincuoft"><i>Development of the Locomotive Engine</i></a> (1907), <a rel="nofollow" class="external text" href="https://archive.org/details/developmentofloc00sincuoft/page/630">p. 630</a>.