Complex sentence: In 1857 Maxwell befriended the Reverend Daniel Dewar, who was then the Principal of Marischal; and, through him Maxwell met Dewar's daughter, Katherine Mary Dewar.
Split into simpler sentences: In 1857 Maxwell befriended the Reverend Daniel Dewar, who was then the Principal of Marischal. Through him Maxwell met Dewar's daughter, Katherine Mary Dewar.