Now this card explores a facet of the Greenwich Observatory that I had never heard of before - and that is that in 1816, the Astronomer Royal (who was, at that time, John Pond), was ordered by the Admiralty to start making magnetic observations, in other words to begin to measure a specific angle that covers a great circle passing through the North and South Pole.
To do this, he needed a special Magnet House, with a long, deep-sunk thermometer and a mast, eighty foot into the sky, which served as the electrometer. This did not last very long, as the house started to sink into the ground, and by 1824 it was demolished.
Curiously, it was not long after this, in 1831, that Sir James Clark Ross announced that he had discovered the location of the North Magnetic Pole, in northern Canada.
What seems unclear is why all of a sudden we started to investigate such a thing.
Anyway in 1835, John Pond left, and he died the following year. His post was taken by George Airy, who was most keen on continuing the research into the magnetic anomalies around the poles, and managed to make the Admiralty build him a purpose built Magnetic Observatory, of wood on a concrete base - simply because iron and brick, etc, can affect magnetic fields and confuse research. He also asked for more, and specialised staff, plus a larger area of ground surrounding the observatory. All this was allowed, though the land does not seem to ever have been used, only fenced off to stop passers by coming too close.
The new Airy's Magnetic Observatory was built by May 1838.
It no longer exists, and nothing can be seen; it is completely covered by the Peter Harrison Planetarium, which is a digital laser planetarium, with seating for a hundred and twenty.
As for magnetic observations, they have not stopped, but they are now conducted at observatories in Eskdalemuir (Dumfries and Galloway), Hartland (Devon) and Lerwick (Shetland Isles).
I thought "Byla" was a brand, but it turns out to be a person, Pierre Byla, who wrote several books on medicine in the early 20th Century. And he is proving elusive.
The company also issued several sets of trade cards, including very attractive ones on costume and peoples of the world - which we will show you in the future.
Our set relates to magnets, but to electromagnets - where a wire is wound into a coil and a magnetic field, along the centre of the coil, is produced by the electric current.
The whole set relates to electricity, and I thought at first that it was alike to the Guerin Boutron set, but it is not, and I cannot find any other issuer of this.
The cards I know of so far are :
- Principe du Telegraph
- Manipulateur Morse
- Recepteur Morse
- Principe du Telephone
- Transmetteur (Telephone de Bell)
- Le Pile Lelanche (P.T.T.)
- Lampe electrique a filament ou a incandescence
- Lampe a Arc
- Tramway Electrique
- Accumulateurs (pour Autos)
- Telephone Domestique (Conversation)
- Transformateur
- Rayons X (ou Rontgen)
- L`Epreuve photo d`un bras
- L` Electro Aimant
- La T.S.F. (Principe)
- T.S.F. (Le Detecteur Electrolytique)
- T.S.F. Poste Recepteur
- Le Cable Telegraphique Sous-Marin
- Radioconducteur de Branly
- La T.S.F. (Croix d`Hins)
- La T.S.F. Sauveteuse - [the SOS distress signal]
But if you know any others, do please let us know!