Flaming object

This occurred many years ago, the late 1970’s, during the summer months as that is when my family usually vacationed at our cabin in northern Ontario on Lake Achigan.  This area is very remote with dense forest and hills.  
One afternoon around 4 or 5 o’clock I was taking our motor boat across the lake.  It was a beautiful day; the sky was blue and cloudless.  
For some reason I looked nearly straight up and saw a flaming "ball" disappear over a nearby hill.  It looked as though someone had taken a paper grocery bag, wadded it up, and set it on fire and thrown it.  
I would guess it was about 500 feet up because I could see it so clearly with flames trailing behind and it disappeared behind an approximately 350 foot high hill.  I would guess it was travelling about 200 mph, but this is a very rough guess as it was so long ago.  
It only lasted a few seconds, but even though it happened so many years ago I can still see it very clearly in my mind.  I don’t know ! if it made any noise or not since I was sitting right next to a running outboard motor.  
I have no idea why I happened to pick that moment to look straight up; perhaps I caught a glimpse of it out of the corner of my eye.  
I still don’t know what to make of it; I’ve never seen anything like it since.  
That’s about it, for what it’s worth.
Witness indicates that the date of the sighting is approximate.  PD