Michael Faraday describes electromagnetic induction (1831)
posted Tuesday, 24 November 2015
Michael Faraday announced the discovery of electromagnetic induction on this day in 1831.
§ 2. Evolution of Electricity from Magnetism.
27. A welded ring was made of soft round bar-iron, the metal being seven-eighths of an inch in thickness, and the ring six inches in external diameter. Three helices were put round one part of this ring, each containing about twenty-four feet of copper wire one twentieth of an inch thick; they were insulated from the iron and each other, and superposed in the manner before described (6.), occupying about nine inches in length upon the ring. They could be used separately or conjointly; the group may be distinguished by the letter A (Pl. I. fig. 1.). On the other part of the ring about sixty feet of similar copper wire in two pieces were applied in the same manner, forming a helix B, which had the same common direction with the helices of A, but being separated from it at each extremity by about half an inch of the uncovered iron.
28. The helix B was connected by copper wires with a galvanometer three feet from the ring. The helices of A were connected end to end so as to form one common helix, the extremities of which were connected with a battery of ten pairs of plates four inches square. The galvanometer was immediately affected, and to a degree far beyond what has been described when with a battery of tenfold power helices without iron were used (10.); but though the contact was continued, the effect was not permanent, for the needle soon came to rest in its natural position, as if quite indifferent to the attached electro-magnetic arrangement. Upon breaking the contact with the battery, the needle was again powerfully deflected, but in the contrary direction to that induced in the first instance.
29. Upon arranging the apparatus so that B should be out of use, the galvanometer be connected with one of the three wires of A (27.), and the other two made into a helix through which the current from the trough (28.) was passed, similar but rather more powerful effects were produced.
30. When the battery contact was made in one direction, the galvanometer-needle was deflected on the one side; if made in the other direction, the deflection was on the other side. The deflection on breaking the battery contact was always the reverse of that produced by completing it. The deflection on making a battery contact always indicated an induced current in the opposite direction to that from the battery; but on breaking the contact the deflection indicated an induced current in the same direction as that of the battery. No making or breaking of the contact at B side, or in any part of the galvanometer circuit, produced any effect at the galvanometer. No continuance of the battery current caused any deflection of the galvanometer-needle. As the above results are common to all these experiments, and to similar ones with ordinary magnets to be hereafter detailed, they need not be again particularly described.
Evolution Day (Origin of Species published in 1859)
posted Tuesday, 24 November 2015
Evolution Day is the anniversary of the first publication of The Origin of Species on 24 November 1859.
Charles Darwin’s On the origin of Species by means of natural selection, or the preservation of favoured races in the struggle for life first appeared on 24 November 1859 and was sold out that very same day. The publisher had been skeptical and had printed only 1250 copies. "Next time write about pigeons, a subject everybody is interested in" he had told Darwin. The word "evolution" is used for the first time only in the sixth edition of the book. The term "descent with modification" is the forerunner of evolution. Even today On the Origin is still being published.
Luna 17 lands on the moon, Lunokhod 1 drives away (1970)
posted Monday, 16 November 2015
Lunokhod 1 was the first roving remote-controlled robot to land on another celestial body. It rolled off the Luna 17 lander two and a half hours after landing and operated for nearly 10 months from November 1970 to September 1971. Although equipped with a laser retroreflector array, was “lost” at the end of the mission and wasn’t relocated until 22 April 2010. More importantly, it looked like a bathtub with eyes.
Voyager 1 made its closest approach to Saturn on 12 November 1980. It took pictures of the planet, then headed for that small moon on the left, Mimas. Wait a minute… That’s no moon. It’s a space station.
The blast blasted blubber beyond all believable bounds…. The humor of the entire situation suddenly gave way to a run for survival as huge chunks of whale blubber fell everywhere. Pieces of meat passed high over our heads while others were falling at our feet…. A parked car over a quarter of a mile away was the target of one large chunk. The passenger compartment was literally smashed…. Everyone at the scene was covered with small particles of dead whale.
The lights went out from New Jersey north to Ontario and east to New Hampshire on 9 November 1965 from 5:30 PM to approximately 5:30 AM the following morning. This is sometimes thought of as the "First New York City Blackout". The second was in 1977 and the third in 2003.