Kodak founder George Eastman insisted that the official company calendar had to use 13 months. What is that all about?
The system was originally proposed by Moses B. Cotsworth in 1902 where its called the "International Fixed Calendar" and it splits the year into 13 months of 28 days each, with one or two days each year not belonging to any month at all. The extra month is called "Sol" and its between June and July.
What was it for? The system was used by Kodak as the official date system until 1989. Can you imagine 60 years of using that sort of calendar? We wonder if the employees got 13 months salary instead too.