Jessop or Jessup?

Once upon a time Jingo Lake Road circumnavigated Jingo Lake. This is clearly shown on an 1879 map of Chaffey Township as well as many resident's property deeds dating from the 1950s. So why is that lake now officially known as Jessop Lake? And is the correct spelling "Jessop" with an "o", or "Jessup" with a "u"? That same map shows two abutting land grants to a Jas. Jessop and a Robt. Jessop, respectively. These are located in the area of Jessup Lane, and in fact, it appears Jessup Lane may well mark the boundary between them -- but it's nowhere near Jessop Lake.

Brian Winterbottom advises us that the Lane was named after a "Chas. Jessup", who's tombstone is dated 1877 -- two years before the map was produced. Was he related to Jas and Robert? If so, is his name mispelled on his tombstone or did a clerk misspell the other names on the roll map?  And what do any of them have to do with the lake? 

 Local historian Karen McAuley-Smith recalls the grave is of  James Jacom Jessup who shuffled off this mortal coil on Jan. 9, 1877.

Chaffey Township Map 1879