# galvanometer

Demonstration galvanometer, circa mid 1800s

20/2/11 - meatpoophysics
• Slept at 3am. Woke up at 7am - My sleep felt like a blink.
• Got to work at 8am, finished at 5:30pm - I was pretty surprised at how much energy I had. I barely felt exhausted and wasn’t in a bitchy mood. I was quite jovial actually and customers had no effect on me.
• A friend ask if I was working out because I was getting “bigger” = big self-esteem but bigger ego LOL.
• Came home and napped.
• Ate dinner then did a beautiful diarrhea. It seriously looked like gravy.

Now onto my physics assignment. Fuck yeah motors+generators!

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On the 29th August 1831 Michael Faraday achieved one of his greatest successes, discovering how to make electricity from magnetism.

Faraday’s first ’Electromagnetic Induction Ring’ is made from 2 sections of wire insulated with cotton and then coiled around opposite sides of an iron ring. When Faraday passed an electric current through one coil he induced an electric current in the other coil, which flowed for a very brief period of time and caused the needle on a galvanometer to move.

He wrote in his scientific notebook:

Aug 29th 1831

1. Expts on the production of Electricity from Magnetism, etc. etc.

2. Have had an iron ring made (soft iron), iron round and 7/8 inches thick and ring 6 inches in external diameter. Wound many coils of copper wire round one half, the coils being separated by twine and calico – there were 3 lengths of wire each about 24 feet long and they could be connected as one length or used as separate lengths. By trial with a trough each was insulated from the other. Will call this side of the ring A. On the other side but separated by an interval was wound wire in two pieces together amounting to about 60 feet in length, the direction being as with the former coils; this side call B.

3. Charged a battery of 10 pr. plates 4 inches square. Made the coil on B side one coil and connected its extremities by a copper wire passing to a distance and just over a magnetic needle (3 feet from iron ring). Then connected the ends of one of the pieces on A side with battery; immediately a sensible effect on needle. It oscillated and settled at last in original position. On breaking connection of A side with Battery again a disturbance of the needle.

4. Made all the wires on A side one coil and sent current from battery through the whole. Effect on needle much stronger than before.

5. The effect on the needle then but a very small part of that which the wire communicating directly with the battery could produce.

From this experiment Faraday would go on to develop the first ever generator a few months later.

Faraday’s Ring and scientific notebook can be found within the museum and archival collections of the Ri.

Michael Faraday’s induction ring, used in experiments that led to the discovery of electromagnetic induction on August 29th, 1831. Faraday wrapped two wires around opposite sides of an iron ring, inserting one into a galvanometer and the other into a battery. He observed “waves of electricity” resulting from the change in magnetic flux.

Sir Thomas Lewis, fetal heart sounds, UK, 1913

“In 1913, Lewis recorded fetal heart sounds together with the mother’s electrocardiogram at University College Hospital, London. By using a twin string carrier designed in that year by WH Apthorpe, he was able with only one Einthoven galvanometer to obtain these two simultaneous recordings. Lewis used the carbon microphone system which Einthoven had designed when he first recorded phonoardiograms in 1907.”

[source]

Leopoldo Nobili’s astatic galvanometer, circa 1820s.

Telegraph Siphon Recorder by Muirhead & Co. Ltd. from the Ballingskelligs cable station in the Irish Republic. This station was opened in 1873 only nine years after the epic voyage of the Great Eastern which laid the first successful submarine cable across the Atlantic. The Siphon Recorder was invented by Lord Kelvin in 1867 for use with the new trans-Atlantic telegraph cable laid successfully at the third attempt in 1865. Due to the length of the cable- 4,000 + miles - there was an immediate requirement for an instrument of unparalleled sensitivity and Lord Kelvin devised the Syphon Recorder to satisfy this need. As sensitive as the mirror galvanometer it had the advantage of also creating a permanent record of the received signal. The recorder translated the incoming signal into a series of squiggles on a paper ribbon. These were then interpreted by a telegraph clerk. Syphon recorders were highly complex and expensive and were only used on long distances where the usual equipment was insufficient, in consequence they were never common and most surviving examples are in museums.