How does this command with which to "refresh the syslog process" work?

On http://www.cs.newpaltz.edu/~easwaran/Resources/commands.html the following command is listed as being meant to "Refresh the syslog process":

kill -1 cat /var/run/syslogd.pid

I have seen this command in real-life use on an embedded device but I cannot wrap my mind around why someone would use it and how it works. I understand the single parts this is made up off, but e.g. why is the cat subshell killed using a HUP signal is not something which makes sense to me.