Eruvin 97: Old-New Tefillin

What happens when you have found tefillin - a machloket between R. Meir and R. Yehudah, specifically regarding new tefillin. How you know you have old tefillin vs. new becomes significant. Also, the significance of checking old tefillin... Also: The case of saving children - from out in the public domain to remove to somewhere more sheltered. What about carrying a barrel - do you really have to carry a barrel? Water becomes the case study. Narrowing the case to facilitate the logic...