Here are a few 19th-century sources that refer to some Roman traditions regarding Janus.
On page 733 of Curiosities of Popular Customs and of Rites, Ceremonies, Observances, and Miscellaneous Antiquities by William S. Walsh (published in 1898 by J. B. Lippincott Company), Walsh states: “Among the Romans, after the reformation of the calendar, the first day of January, as well as the entire month, was dedicated to the eponymic god Janus… . Throughout January the Romans offered sacrifices to Janus upon twelve altars, and on the first day of that month they were careful so to regulate their conduct that their every word and act should be a happy augury for all the ensuing days of the year.”
On page 66 of The Churchman, a Magazine in Defence of the Church and Constitution, Volume IV, from January to June, 1841, published in London by William Edward Painter, it says: “The first of January was kept as a high festival by the heathens, who offered sacrifices on that day to Janus. In such veneration was it held by the Roman people in particular, that, although their festivities were marked by excesses of every description, not only were the most deadly animosities suspended, but enemies, however inveterate, mutually refrained on this day from even passing a reflection on the character or conduct of each other. It was also the chosen period at which every work of art, of science, or of labour, was commenced.”
As to the temple of Janus and the tradition of the doors, here is some further information:
On page 435 of Bibliotheca Classica: Or, A Classical Dictionary by John and Thomas Dymock, published in London in 1833 by Longman, Rees, Orme, Brown, Green, & Longman, it says: “Numa Pompilius built a temple to him at the foot of Argiletum, which was to be open in time of war, and shut in time of peace. The latter only took place three times during the period of seven hundred years after its erection, the first under Numa, the second at the end of the first Punic war, and the third after the battle of Actium… . Macrobius gives [Janus] different names: Janus Geminus, Janus Quirinus, Janus Patulcius, and Janus Clausius, the last two from the doors of his temple being open in war, and shut in peace… .”
There are also ancient Roman coins showing Roman emperor Nero on one side. The other side depicts the Temple of Janus with its doors closed, surrounded by the words: PACE P R TERRAMARIQPARTAIANVMCLVSIT S C. As we understand it, this means roughly “The peace of the Roman People having been established on land and sea, he closed the doors of Janus.”
Here are a few 19th-century sources that refer to some Roman traditions regarding Janus.
On page 733 of Curiosities of Popular Customs and of Rites, Ceremonies, Observances, and Miscellaneous Antiquities by William S. Walsh (published in 1898 by J. B. Lippincott Company), Walsh states: “Among the Romans, after the reformation of the calendar, the first day of January, as well as the entire month, was dedicated to the eponymic god Janus… . Throughout January the Romans offered sacrifices to Janus upon twelve altars, and on the first day of that month they were careful so to regulate their conduct that their every word and act should be a happy augury for all the ensuing days of the year.”
On page 66 of The Churchman, a Magazine in Defence of the Church and Constitution, Volume IV, from January to June, 1841, published in London by William Edward Painter, it says: “The first of January was kept as a high festival by the heathens, who offered sacrifices on that day to Janus. In such veneration was it held by the Roman people in particular, that, although their festivities were marked by excesses of every description, not only were the most deadly animosities suspended, but enemies, however inveterate, mutually refrained on this day from even passing a reflection on the character or conduct of each other. It was also the chosen period at which every work of art, of science, or of labour, was commenced.”
As to the temple of Janus and the tradition of the doors, here is some further information:
On page 435 of Bibliotheca Classica: Or, A Classical Dictionary by John and Thomas Dymock, published in London in 1833 by Longman, Rees, Orme, Brown, Green, & Longman, it says: “Numa Pompilius built a temple to him at the foot of Argiletum, which was to be open in time of war, and shut in time of peace. The latter only took place three times during the period of seven hundred years after its erection, the first under Numa, the second at the end of the first Punic war, and the third after the battle of Actium… . Macrobius gives [Janus] different names: Janus Geminus, Janus Quirinus, Janus Patulcius, and Janus Clausius, the last two from the doors of his temple being open in war, and shut in peace… .”
There are also ancient Roman coins showing Roman emperor Nero on one side. The other side depicts the Temple of Janus with its doors closed, surrounded by the words: PACE P R TERRA MARIQ PARTA IANVM CLVSIT S C. As we understand it, this means roughly “The peace of the Roman People having been established on land and sea, he closed the doors of Janus.”
Hope this helps!