Unoften

[B]evvare of Paſſion, as the moſt Capital enemy to the Crovvn and Empire of Reaſon: for thoſe Sons of Thunder […] if vve mark the Cataſtrophe of their turbulent lives vve ſhall find them concluded in a tempeſt, and not unoften like the Phœnix expire in a funerall pile themeſelves had kindled.

Source: wiktionary

In ſummer, it removes to ſome diſtance from the houſes, alvvays chooſing the lovver countries about the mills and ſtreams, hiding itſelf among the buſhes, in order to catch the birds, and not unoften taking up its habitation in the hollovv of an old vvillovv, vvhere the female may vvith greater convenience bring forth her young.

Source: wiktionary

[T]he patricians of Rome were not unaccustomed to the rude fellowship of these brawls; nor was it unoften that the mere presence of a noble sufficed to scatter whole crowds, that had, the moment before, been breathing vengeance against his order and his house.

Source: wiktionary

Of deep concern for us has been the question of machinery for the implementation of land reforms. The present administrative set-up for the purpose, comprising as it does low revenue officials who not unoften belong to the upper crust of our rural society and are interested in non-implementation of land reform measures, has proved very unsatisfactory indeed.

Source: wiktionary