Nikolai Grigoryevich Egorov (19.09.1849 —22.07.1919) was a Russian experimental physicist. He was born in St Petersburg. He graduated from St Petersburg University (1870). In 1873-77 he was an assistant at the Technological Institute (St Petersburg), in 1878 —84 professor at the University of Warsaw, and in 1884 —1900 at the St Petersburg Military Medical Academy. From 1894 he worked at the Main Chamber of Weights and Measures (director from 1907).
His work was in the field of spectral analysis, electromagnetism, radioactivity and metrology. He studied the solar spectrum, the absorption spectrum of the Earth's atmosphere, and X-rays and their properties. He proposed (1897) a new way of observing the Zeeman effect. He organised the first X-ray laboratory in Russia and did much to introduce the metric system.
He was vice-president of the Russian Physico-Chemical Society (1902 and 1910).