February 1856

24 February 1856: 🚪death of Nikolai Ivanovich Lobachevsky [ 🐭 1792-1856, IPA-ru: [nʲɪkɐˈɫaɪ̯ ɪˈvanəvʲɪt͡ɕ ɫəbɐˈt͡ɕefskʲɪɪ̯], Runr: ᚾᛁᚴᛟᛚᚨᛁ ᛁᚡᚨᚾᛟᚡᛁᚲᚺ ᛚᛟᛒᚨᚲᚺᛖᚡᛋᚴᚤ] (63 years old)

Russian mathematician and geometer, known primarily for his work on hyperbolic geometry, otherwise known as Lobachevskian geometry, and also for his fundamental study on Dirichlet integrals, known as the Lobachevsky integral formula RE/SU/RU-NIZ/RU-TA

January 1924

21 Jan 1924: 🚪death of Vladimir [Ilyich] Lenin [IPA: [vɫɐˈdʲimʲɪr ɪˈlʲjit͡ɕ ˈlʲenʲɪn], Runr: ᚡᛚᚨᛞᛁᛗᛁᚱ ᛁᛚᚤᛁᚲᚺ ᛚᛖᚾᛁᚾ] (53 years old)

Russian revolutionary (real surname: Ulyanov [IPA: [ʊˈlʲjanəf]🐮♉🐂|🌸🌺, Runr: ᚢᛚᚤᚨᚾᛟᚡ; also known as Ulyanov-Lenin, RE/SU=>RU-ULY/RU-TA/RU-SPE)