Transcript: In 1872, Henry Draper was the first man to photograph stellar spectra. This was a huge advance on previous practice which just relied on naked eye observations or visual observations where the features in the spectrum had to be described and then transcribed or written down. Draper started on a long project to photograph all the bright stars in the night sky and classify their stellar spectra. He died before the project could be finished, but he left in his will money to Harvard College Observatory to continue and finish the project. Edward Pickering led the project, but most of the work was done by a small set of female computers who actually, by eye, classified tens of thousands stellar spectra in the most tedious and painstaking way imaginable. The first classification was based on the strength of the hydrogen absorption features in the stellar spectrum. Class A of stars had the deepest hydrogen features, class B the next deepest, C the less deep, and so on up to letter P. Most of the features in the spectra were from hydrogen and some were from helium. All other features due to other elements were lumped together in the category called metals which is clearly a misnomer because many of the elements heavier than helium are not actually metallic.