Here.
Mr Thomas Horan brought this to my attention a while back. Never mind his other interesting theories; it's a fabulous and interesting observation, this.
Here's is an image of the "Stine" letter.
If you look at it the right way up, the "d's" look funny.
They've been described as oddly "cursive" in the past - as a characteristic handwriting trait, one that sets him apart, etc. etc.
Turn it upside-down and have a look. Here:
Aren't they odd. Don't they look just like letter "p's" drawn in with the paper upside-down?
Would it explain the strange spacing in some words (such as the ones Morf and I like so much, the "ght" endings) if the writer was rotating the paper, to disguise certain characters? I think perhaps it would. Sometimes the writer seems to leave too much space for his upside-down characters - sometimes (such as in the Stine letter "dd's" )- it throws the character baseline's off.
I've circled the "p's" too, They also look a little strange. The "rest" marks where the pen's stayed on the paper longer are interesting.
Since he obviously disguised his handwriting in the Riverside letters (if not so well on the envelopes), then......
