Print out a few pages of the PDF. Cross-reference the monsters listed in Journal 1 with the monsters who appeared in the Society of the Blind Eye episode. You will notice the Society knew about Journal 1 before Dipper did.
This is the question that splits the fandom. Gravity Falls Journal 1 Pdf
The Short Answer: No official, studio-released PDF exists. Disney has not digitized Journal 1 for public consumption. Print out a few pages of the PDF
The Long Answer: Yes, fan-made recreations exist. This is the question that splits the fandom
Over the last seven years, hyper-dedicated fans (using screenshots from the show, the Journal 3 special edition, and background props from the DVD extras) have compiled what they believe to be the contents of Journal 1. These are unofficial, watermarked, or incomplete.
The complete series box set includes a featurette called "The Secrets of the Journals." In this short, Alex Hirsch physically turns pages of the actual prop of Journal 1 used in the studio. You can pause the video and read along. This is the closest you will get to a high-resolution "PDF" legally.