In the spectrographs used by Thomson until 1910, the rays of positive electricity were detected by the phosphorescence they produced on a willemite screen. The screen was made by grinding rare zinc mineral willemite into a fine powder. After shaking in alcohol, the suspension was allowed to deposit slowly on a glass plate. Later, a photographic plate inside the spectrograph was used for more sensitive detection.
The solution of differential equations of this type came from the French mathematician Émile Léonard Mathieu (1835-1890), who studied the mechanical vibrations of the elliptical drumheads.
The International Prototype of the Kilogram was a cylinder with a height and diameter of 39 mm made of an alloy of 90% platinum and 10% iridium.
During the war, copper was preferably used for the production of brass shell casings and it was not available for the construction of calutrons. The designers came up with the idea of replacing copper with silver. They borrowed about 13,300 tons of silver from the West Point Bullion Depository in West Point, NY. After the war, the silver was returned to the Treasury with virtually no loss.
Josef Mattauch was born in 1895 in the city of Mährisch Ostrau, in what is now the Czech Republic, then part of the Austrian-Hungarian Empire.
The particle carries one elementary charge, the value of which is 1.602 176 634 × 10−19 C (exactly).
Aston is a 44-kilometer lunar impact crater located along the northwestern limb of the Moon. The crater was named in honor of Francis W. Aston.
The parents of John Zelený, Antonín Zelený and Josefa Pitková, came from Křídla, a small village near Žďár nad Sázavou in Austria-Hungary (now the Czech Republic).
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