Speaking of typos, go to the second or page 47 of the Bill Lockhart / Bill Porter article and notice on Figure 2 and Figure 4 where the caption says the images are for the 1916 patent and not 1915. I guess even experts make errors from time to time. Here's the link again ... http://www.sha.org/bottle/pdffiles/coca-cola.pdf
Also, notice that the bottle is shorter and fatter than a standard 1915 or 1923 bottle. darker aqua is 1916, to the right is a 1915, to the left a Jacksonville straight sided, to the further left, a 1923. The 1916 error bottle is exactly the same height as the Jacksonville bottle.FullSizeRender-5.jpg
I've been doing some research and my initial findings lead me to suspect the number 4 might represent one of the four plants operated by the Graham Glass Company. On page 52 of the Bill Lockhart/Bill Porter article it shows a chart of the four Graham plants, which were located in ... 1. Loogootee, Indiana ~ 19172. Evansville, Indiana ~ 1918-1927 3. Okmulgee, Oklahoma ~ ca. 1920-19264. Chacotah, Oklahoma ~ 1921 Remember, the Patent 1915 bottles were being made as late as 1928 and as late as 1930 by Root Glass. So the 1916 error bottles could have been made anytime between about 1917 and 1928. Additional evidence of my Graham Glass theory is found in Bill Porter's Coca Cola Checklist book where, on page 4, he states ... (in part) "Graham Glass Co., Evansville, Indiana. Until 1920: no mark but usually a large mold number on the base." Hence, my current guess is the 1916 error bottles were made by the Graham Glass Company at one of their four plants and the number 4 represents that particular plant. And because Graham didn't start using a makers mark until 1920, I'm guessing the 1916 error bottles were made sometime between 1917 and 1920.
Excellent work Bob!...I would agree with your findings that it would be a plant #, evidence being that all those bottles are variations. I have a Coke bottle that had been retooled and the patent date removed and the mold # relocated...on the retooled version you can even see under close examination where they peened out the old location of the #. It's amazing to see!...it's like DNA of a bottle!
Leon: I'm not a Hutchison expert, but based on what I know about them, they were produced well into the 1920s. So I'd say its possible your Hutchison bottles were made by the Graham Glass Company and the #3 and #4 might represent one of their four plants. Based on the brand names on your Hutchinson bottles, do you happen to know approximately when they were made? As for a solo 3 on the base or heel of early Coca Cola bottles, I'm not aware of any but suppose there could be. ???