Friesian School
Proceedings of the Friesian School/the Quantacized Atom
A very lengthy page from friesian.com discussing Bohr's theory of electronic energy levels and the explanation of commonly observed atomic emission line spectra. The concept of a photon and Einstein's observation of the photoelectric...
Wikimedia
Wikipedia: Prime Meridian
This site from the Encyclopedia Wikipedia provides an encyclopedia article on the prime meridian discusses the important principles were established at the International Meridian Conference in 1884.