Bondi was the landing point for Compac and at the end of our Cable Course in 1972, Percy Day took us on a tour of the cable path through Centennial Park and the streets of Bondi. Percy toured the Compac Cable path every Monday to make sure that there was no construction work that would put the security of the cable at risk.
We visited the cable entry room and noted that there was more than just the Compac Cable in the room. In fact there were many old telegraph cables terminated in the room and one of the universities was graphing the voltage / current generated on the cables by the earths changing magnetic field. Percy had to check the paper recorders and mark the dates.
Percy Day – marking the time and date. top is Mick?, below left is an Eng Branch person, below right is Doug Llyod, under him is Len Vella and Con ? – he was a trainee that came through at around the same time as me and worked briefly in the ITMC before leaving OTC
Would someone good at remembering names remind me. Give me numbers and events and I am fine. Names escape me over time. Sorry.
The science here was wonderful. Thousands of kilometres of wire laid on the ocean floor and short circuit to the ocean at the distant end due to a cable break – maybe due to an earthquake. The lengths of cable are lying in the changing earth’s magnetic field.and are thus generating a tiny current as the earth’s magnetic field changes. A magnificent experiment. The cables radiated north and east. You could not have built such a test from scratch. Even modern repeater cables would not work as they had resistive drops to power each repeater 45kms or so. It had to be the very old cables that signaled by Morse Code! Looking at the phases of the change it is possible to precisely plot the changes in the earth’s magnetic field and where the poles have moved. The
It is interesting to see the old massive 1.5 volt batteries – a thing of the past. They often used batteries like these on telephones in the old days before exchanges provided the 50V to power the microphones. They also used them for filament supplies for battery operated valve radios. Here they were powering the paper records as there was no mains power in the cable room.