1897 Russian Census in Poland
In years 1795-1918 great part of Poland was under control of Russian Empire. In 1897 in that area was performed First National Census of Russian Empire. Each household was listed including names of all residents: parents and children.
Unfortunatelly for Polish area lists of hausholds were distroyed and only statistical summaries survived, so this kind of records should not be considered as a resource for Polish genealogy.
Probably some resords from that census survived for Łomża city and villages from that county.
More infromation can be found HERE.