Clark's tables

[Geocentric]

In Clark's tables, atomic masses of certain isotopes has a number written as subscript. What is its significance?I have just completed my bachelors degree in Physics and don't know such a basic thing. Its really shameful, isn't it?Maybe I never thought about it.Somebody please help.

[sanctus]

Can you post a scan of it? I'm not sure if i understood you right.
Anyway I'm doing my master thesis now, also in physics, and so in case I don't know we can be both ashamed.
[begin: philosophy nerd]
But you know this following Socrates we are (or will be) more intelligent because "we know not to know"...
[/end philosophy nerd]