Paul Eggert wrote:
By the way, was Bern Mean Time actually exactly 29 minutes and 44 seconds ahead of GMT? Our only source for that is Shanks.
I have not seen an official document yet which defines the Swiss time standard of 1854 - 1894. Maybe I will make another trip to the Zurich central library to check the law collection. Traditionally the locations of astronomical oberservatories were used as reference point. The 'Alte Sternwarte Bern' (old Bern observatory) was used as the reference point for the national swiss geodetic system of 1903, Its location is given in http://www.swisstopo.admin.ch/ as Latitude = 46° 57' 08.66" geogr. Breite des Nullpunkts in Bern (**) Longitude = 7° 26' 22.50" geogr. Länge des Nullpunkts in Bern (**) This longitude converted to time gives 29m45.5s which is 1.5 seconds off the Shanks value. As far as I know Thomas Shanks (whom I personally met in 1987) has always second values which are a multiple of 4, and I presume this comes from the fact that he rounded longitude to integer minutes. He gives as longitude of Bern 7°26' and therefore arrives at 29m44s. -- || Alois Treindl, Astrodienst AG, mailto:alois@astro.com || Zollikon/Zurich, Switzerland || Free astrological charts at http://www.astro.com/ || SWISS EPHEMERIS Free Edition at http://www.astro.com/swisseph/