First Costa Rica workout- Week 1

My very first day in San Jose I ran to La Sabana park from La Uruca- approximately 2 km away. This workout required only a pull-up bar so I walked around the park and found an old swing set w/out the swings. It was kind of high so I rolled a concrete block underneath the bar. It's still there so if you ever want to use it feel free. The workout went as follows, however I don't think I did it correctly.

With a continuously running clock do one pull-up the first minute, two pull-ups the second minute, three pull-ups the third minute... continuing as long as you are able.
Use as many sets each minute as needed. (http://www.crossfit.com/mt-archive2/003801.html)

Considering my level of fitness at this point, I think I did ok with 7 minutes and a total of 28 pull-ups.