I have a third-story window that goes out to a grove of oak trees
where I want to attach a clothesline from the window to the trees
about100 feet away.

I will go to Home Depot and ask for clothes line, but, before I do,
do you have experience with something like this that you can make
recommendations?

Clothes line here is 10 ga galvanized; been up for over 70 years so far
and counting...

As another said, however, for that purpose you're going to have to do
some serious engineering to keep from yanking the window frame out of
the house plus it's got to be more flexible than the wire to be able to
be off the pull the top side closer to take the bottom away to be able
to put anything more than one or two items on it...

So, for that application, no, I don't have any recommendation,
specifically other than I'd probably rethink the idea.

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