What is the Hazel-Atlas Mark?

Hazel-Atlas mark on the base of a “rust” or orange-brown colored Platonite bowl. Hazel-Atlas well-known makers mark consists of a large capital letter “H” with a smaller capital “A” positioned underneath the H, appearing somewhat like a small step-stool or bench situated underneath a table.

What do the numbers on the bottom of blue Mason jars mean?

Many Ball mason jars have a number printed on the bottom of the jar, but this is a mold number that does not indicate the year of production. Rather, the mold number tells you where the jar was positioned on the glass-making machine that was used to produce it.