Just picked up this Trenton.  Looks like serial #  A 7101 on the right side although it looks like T121 on the left side.  Any ideas why it would have two holes drilled through it?

There would have been one more number on that serial number for that style of logo. A7101x that would be 1907 according to Anvils In America.

The holes in the side are odd, as is what looks to be a large bolt head on the underside of the base? Sometimes there was a square handling hole there.   Guessing this anvil possibly had a cracked waist and these are the evidence of repairs...

It would appear that it has been broken at the waist at some and the 2 holes probably had a metal plate to hold the top and bottom together. The large bolt in the bottom has also been added. It appears that the split has been welded and ground smooth. Unable to tell if it was full depth welded or just surfaced welded.

A7101 would make it 1899 but it appears to have another number after the 1 which would make it 1907.

Does it have a ring if you tap it with a hammer?

Maybe the last # is 2.  Looks like maybe the bottom right corner has part of a 2

My Trenton might get upset if I dated yours. She dosnt like me messing around with other anvils. Ah, someone had to.  

Has a good ring and rebound

If it has a ring it's not just dating it's engaged, maybe married. (beat you to it that time Das. )

Frosty The Lucky.

Your just trying to be the rebound man.  

No need to hammer it home Daswulf

This could be one reason for the hole in the side of the anvil.  

I have seen one anvil with a bolt hole in the bottom to secure it to a metal work table and prevent theft.

Thanks Glenn.  That's an interesting Patent. 

I thought of a variation on a chainmakers anvil that has an adjustable rest