A part of reorganising my work area I consigned a number of books into storage One took my interest again as my grand father worked on a sailing ship of the White Star line I was fairly set in my mind that sailing ships used the 'roaring fourties' to come across to Australia In the booklet 'Settlers under Sail" by Don Charlwood he mentions aspects which I had overlooked - as such I thought it worthy of repeating in brief form that to the list 1. an essential instrument was a reliable chronometer 2. they were generally set on Greenwich Mean Time through out the voyage (for GMT one can see references now being also UCT - universal coordinated time) 3. where the navigator could see the sun at it zenith he could determine how many hours it varied from GMT 4. Each hour of difference equated to 15 degrees from Greenwich and so he could determine the longitude of the ship 5. The same sighting, by reference to navigational tables could provide latitude 6. In COOK's time chronometers were expensive 7. John TOWSON of Liverpool produced small cheap models and as the examiner of ships at Liverpool urged each master going to Australia to follow the composite great circle* 8. Astonishing short passage times can about because of this 9. Masters were no longer bound to the roaring fourties from Cape Town to Cape Otway (that destination mentioned as this book in the main focused on Victorian shipping) 10. Ships often sailed 800 miles south of Cape Town - latitudes of 50 or even 55 degrees south 11. Darkness often fell soon after 4pm I thought this was interesting and informative regards Alan HALL Melbourne * great circle route - the shortest course between two points on the surface of a sphere. It lies in a plane that intersects the sphere's centre and was known by mathematicians before the time of Columbus.