There is more history leading to the inception of leap seconds evident in close inspection of the issues of Bulletin Horaire.
During the early 1960s the German federal time broadcast station DCF77 did not broadcast time signals 24 hours a day. Historically this was also true of many other time broadcasts which used equipment that was shared between many purposes. As the 20th century progressed many time signals were generally broadcast during those hours when the ionosphere was quiescent between transmitter and the expected set of navigational users. Ships near those transmitters knew to tune in and check their clocks at the right time. Furthermore, the signals from different places did not agree with each other, but they did agree with longitudes on local navigational charts. Different regions of the earth had assumed different local origins of longitude when making their charts, and those were not globally consistent with Greenwich at the fine level. Time was longitude, and longitude was time, and they had to agree. The local broadcasts used times offset from each other, but consistent with the charts in use. These broadcast time offsets persisted until new charts were issued and decreed to come into general use. I suspect that close inspection of regional navigational charts in the 1960s will show changes that are consistent with those of the time signals. In the early 1960s the DCF77 broadcasts were run by the German Hydrographic Institute for the sake of navigation. The time scale was not "coordinated". This continued several years after the various scientific bodies and CCIR Rec 374 said that everyone should be broadcasting the "coordinated" original form of rubber second UTC. About 1965 DCF77 changed its broadcasts such that there were two different kinds of broadcasts at different times of day. (Bulletin Horaire is not entirely clear on when; it had always been the case that BIH learned about a lot of changes after the fact.) The German Hydrographic Institute continued to control broadcasts at some times of day, and those were the CCIR-approved form of rubber second UTC. At other times of day the broadcasts were controlled from the German Metrology Institute (PTB). The PTB-controlled broadcasts were pure SI seconds thus making those broadcasts a form of Stepped Atomic Time which was approved as experimental by CCIR Rec 374-1 in 1966. Sometime after 1967 October when the CGPM approved the SI second based on cesium the German broadcasters convinced themselves that the rubber second form of UTC was no longer legal to broadcast in Germany. This departure from the agreed form of "coordination" led to the urgent series of CCIR working group meetings during 1968 and 1969 which resulted in the proposal for leap seconds presented to the CCIR assembly in 1970 February. -- Steve Allen <s...@ucolick.org> WGS-84 (GPS) UCO/Lick Observatory--ISB 260 Natural Sciences II, Room 165 Lat +36.99855 1156 High Street Voice: +1 831 459 3046 Lng -122.06015 Santa Cruz, CA 95064 https://www.ucolick.org/~sla/ Hgt +250 m _______________________________________________ LEAPSECS mailing list LEAPSECS@leapsecond.com https://pairlist6.pair.net/mailman/listinfo/leapsecs