How much music (time) could a 10" 78 hold?

[medjuck]

I notice that the alternate take of the Keystone "Sometimes I'm Happy"  on the new Mosaic Prez box set is 3:44 long.  They did do a 2nd take that is faster and hence shorter but is this possible because the recordings were cut on a larger disc and then transferred?  And why does the alternate take have "(BD)" after it's listing? 

[jeffcrom]

A 10" 78 generally ran about three minutes, although I've got a few which push three and a half. By the 1940s many studios were recording onto 16" acetate discs, but I don't know the details of how those were turned into masters and stampers.

[Chuck Nessa]

At least in the beginning (if not always) the 16 incher was a back-up/file copy of the single masters recorded. Thankfully, these discs provide clean reissues for the rest of us.

[medjuck]

And I suspect in the case of "Sometime's I'm Happy" an alternate take when Lps were  issued.