early block casting number

[Scott Rosenthal]

1909 blocks that do not have casting dates, but have an approximately 3/4" tall numeral cast in the middle of the right side. There have been random discussions about this feature, where I am not aware of conclusive information that determined what this number represents. A member here recently posted that he believed the numeral "3" indicates blocks made in 1911, where this example would be of much interest if correct, since there were both open and closed valve blocks produced for 1911. If correct, would this assumption indicate that both open and closed style blocks bear the number "3"? Would all of the water pump blocks then have a common similar coding system? I have also seen block examples where in addition to the cast numeral, there is a "period" after the numeral....many thanks for any ideas as to what this particular feature denotes?

Related, Were blocks produced by multiple foundry suppliers, and would there not have been a need to segregate which finished castings originated from which pattern sets? Perhaps there are discussions out there that talk about the quantity of molds in play and how this supply line was controlled? Many thanks for thoughts/comments.
Regards,
Scott

[Dan Hatch]

Is not that number the mold number? Like mold number 3. So they could kept up with where a problem was? Thanks Dan