Lunar calendar or crescent moons and others employing detailed calculations. Since each lunation is approximately days (29 days, 12 hours, 44 minutes, 3 seconds, or days), it is common for the months of a lunar calendar to alternate between 29 and 30 days. Since the period of twelve such lunations, a lunar year, is only 354 days, 8 hours, 48 minutes, 34 seconds ( days), purely lunar calendars lose around 11 days per year relative to the Gregorian calendar. In purely lunar calendars like the Islamic calendar, the lack of intercalation causes the lunar months to cycle through all the seasons of
1928 Isle of Man TT held in heavy rain and mist. The bad race conditions produced many retirements and a slow average speed. The eventual winner of the 1928 Senior TT Race was Charlie Dodson, riding a Sunbeam motorcycle, in 4 hours, 11 minutes and 40 seconds, at an average speed of . 1928 Isle of Man TT In the 1928 Isle of Man Tourist Trophy the newly developed 'positive-stop' foot gear-change by Velocette gave Alec Bennett his fifth TT Race win in the 1928 Junior, in the time of 3 hours, 50 minutes and 52 seconds, at an average speed of , and setting