An item in the basement of the Herman Melville House: what is it?

Unidentified wood device with metal parts, square nuts, and washer nuts, and hex nuts in basement of Melville House
Unidentified wood device with metal parts, square nuts, and washer nuts, and hex nuts in basement of Melville House, reverse side
Unidentified wood device with metal parts, square nuts, and washer nuts, and hex nuts in basement of Melville House, medium closeup of top