Yes, when I received my 40th patent, a friend cited this swing patent as an example of the fact that patents can be trivial. In this case, the kid who invented it may have thought he invented something new - and the examiner must have been enough of a geek never to have played on a swing and discovered the prior art himself. Nevertheless, as eng_steve observed, the patent was quickly reversed. It is unfortunate that the patent reversal appears as the final page of the patent so the casual reader may miss it. Maybe overturned patents need a big "X" across the first page.
Fortunately it's a fairly weak patent that doesn't outlaw Lissajous patterns or strange attractors.
I presume what the author was thinking was to demonstrate how silly the system can get. The Patent Office alone know what they were thinking (if anything).
Next patent "method for licking an ice cream"
Uff!!... So if you are eating a crustless sandwich while swinging in a swing, you can really get in serious trouble.
Thousands of children around the world are incurring in this double patent infringement, somebody should advice them before being too late!!