After noon all, Is there a formal definition of what constitues an entrance series of a cave? or is it set for each cave? or is it a vague thing like saying "the first bit"? I know what the entrance series for Swildons is i.e. anything above water chamber maybe as far as the 20, but what...

Off on a tangent from Stu's thread.(http://ukcaving.com/board/index.php?topic=11296.msg145738;topicseen#new) Why do modern lamps have set brightness levels rather than continuous dimming? With bulb lamps its simple, 2 bulbs, 2 brightness levels. To have more levels mean more bulbs hence more...