Point Google to “holroyd sudan 1837” for a fascinating evenings reading.
Arthur Todd Holroyd was an English physician and explorer. The first European to cross the Bayuda Desert he also lived in Wellington and Sydney . For a good read go to :
https://wanderinground.wordpress.com/tag/arthur-holroyd/
and to :
http://www.pbase.com/image/96048691
for Happypoppeyes take on this shot and his brilliant people photography.