Two types of /n ~ ø/ alternations have been considered here. One is an alternation between /-i/ and /ni/ of the genitive-instrumental case-marker after the /ng/ sound, and the other is an alternation between /emu/ and /nemu/ of the numeral “one”. The former /-i/ ~ /ni/ alternation was not active during the Nurhaci era (~ 1626), more than 80% of genitive-instrumental case-marker tokens being of the shape /-i/ irrespective of the preceding sound, as in /ing -i/ “of the camp”. At the beginning of the Hongtaiji era Tian-cong 1 (1627), five years before the Manchu orthography was reformed, the percentage of /ni/ genitive-instrumental after /ng/ rises suddenly, as in /ing ni/ “of the camp” rather than /ing -i/. Eventually this form becomes a standard form in the Peking era (1644 ~). The latter alternation between /emu/ and /nemu/ is interpreted as follows. The basic form /emu/ “one” changes to /nemu/ after double figures ending in /n/, e.g., /juwan/ “10” + /emu/ “1” → /juwan nemu/ “11”. This type of /emu/ ~ /nemu/ alternation has been well preserved from the earliest records of the Manchu script of the Nurhaci era until Chong-de 4 (1639) of the Hongtaiji era, seven years after the Manchu orthography was reformed, and after that almost all records show exclusively /emu/, e.g., “11” is /juwan emu/ rather than /juwan nemu/. These two changes reflected in the Manchu script do not correspond with the time of the Manchu orthographic reforms (1632). Evidently, some unknown political influence must be taken into consideration.