Caned oak fixed leg rocking chair

Just found this in a thrift shop today and have never seen anything like it before. There is a coiled spring at the back corner of the seat between it and the second "layer ". There are pegs at the front corners attached to the seat which act as a spacer and come in and out of the second "layer". The rest of the chairs construction is similar to any other oak dining chair I've seen. Would greatly appreciate any information regarding era, what this type of chair was actually called etc. Possibly a chair intended for use with a desk ? But it doesn't swivel. Many thanks in advance :-)