The Japanese text is
謹賀新禧
廿五年一月一日
出南七三郎
久常村河原新保
宮川豊次様
The first line means Happy New Year or New Year's Greetings.
The second line is the date. The first day of the first month of the 25th year (most likely of the Meiji Era), which is January 1st, 1892.
The third line is the name of the writer, a Minami Shichisaburo.
The fourth line is the address of the recipient. The village of Hisatsune, Kawahara Shinbo district. The village of had recently been created in 1889 by merging 8 villages that had previously existed in the area, one of which was the village of Kawahara Shinbo. Now a days it's part of the city of Nomi in Ishikawa Prefecture.
The fifth line is the recipient of the letter, a Miyagawa Toyotsugu, Miyagawa Bunji, or Miyagawa Toyoji (With names it's sometimes impossible to tell which of various possible pronunciations is the correct one by writing alone)
This is a New Year's card, which Japanese people send to those they know as a form of greeting, somewhat similar to the western concept of Christmas Cards. Judging by the lack of any content other than the greeting in the first line, the two people were not likely very close. And since the stamp on the corner is from January 2nd, even though the date on the card is January 1st, the writer had probably forgotten about the card and sent it a day later than he had planned on doing. That or he forgot about the recipient and hurriedly wrote the card on January 2nd and fibbed about the date on card.
Thank you to echigoya_mitsuemon on Yahoo Chiebukuro for deciphering the Japanese text.
Are you sure about the date? In the 1700s Japan didn't have a post office yet. Based on the stamp on the second image I'd say it's from January 2nd, 1882.