20.???(1) A tent, van, shed or similar structure used for human habitation, or a barge, lighter, boat or other vessel on any river, canal or other inland water (in this section referred to as ???a barge???) used for human habitation, which is in such a state as to be a nuisance or injurious to health, or which is so over-crowded as to be injurious to the health of the inmates (whether they are or