So I have ElementTree 1.2.6 on my box now, and ran the following code against the XML chunk you posted:
import elementtree.ElementTree as ET
tree = ET.parse("test.xml")
doc = tree.getroot()
thingy = doc.find('timeSeries')
print thingy.attrib
and got the following back:
{'name': 'NWIS Time Series Instantaneous Values'}
It appears to have found the timeSeries element without needing to use numerical indices.
What would be useful now is knowing what you mean when you say “it doesn’t work.” Since it works for me given the same input, it is unlikely that ElementTree is broken in some obvious way. Update your question with any error messages, backtraces, or anything you can provide to help us help you.