http://solrserver:8080/solr/notes/select?q=*%3A*&fq=type%3Apathology&rows=0&wt=json&indent=true&facet=true&facet.date.gap=%2B1DAY&facet.date=date&facet.date.start=2014-07-01T00:00:00Z&facet.date.end=2014-08-01T00:00:00Z
If you're using the the Solr management web UI, you can paste this into the Raw Query Parameters:
facet.date.gap=%2B1DAY&facet.date=date&facet.date.start=2014-07-01T00:00:00Z&facet.date.end=2014-08-01T00:00:00Z
This will count the number of exams in each 1-day period in July.