<a href="https://en.wikipedia.org/wiki/Bessemer_process" class="extiw" title="en:Bessemer process">Bessemer converter</a> blowing
<a href="//commons.wikimedia.org/wiki/User:Borvan53" title="User:Borvan53">Borvan53</a>
<a rel="nofollow" class="external text" href="https://archive.org/stream/principlespracti00macfrich#page/76/mode/1up">The principles and practice of iron and steel manufacture</a> p. 76