"Duraglas" Glass Jar [Owens-Illinois]

On this cute little "Taper Mustard" jar, Owens-Illinois Glass Company's logo for their proprietary bottle-making process, "Duraglas" is embossed along the bottom edge twice (opposite from one another in location along the bottom).

The trademark embossed on the base is the diamond IO mark, and to the left of the mark is a one- or two-digit number that identifies the plant that produced the jar.  To the right of the mark is a one-digit number that identifies the year the jar was produced.  If there happens to be a period following the number on the jar, then it was manufactured in 1940 or later.

The base shows the Owens-Illinois trade mark with the number 2 to the left of the mark and the number 9 (with no periods following) to the right.  The number 15 is embossed below the mark.  This indicates that this jar was manufactured in plant number 2 in Fairmont, West Virginia, in 1939.

In addition, there appears to be a stippling (numerous small dots) on the base of the jar, something that began showing up around the same time Duraglas was first introduced.