It's knitted in very fine cotton - the whole thing measures only about 17cm.× 22 cm. (6½ in. × 9 in.). We think that it might have been intended to be a pincushion cover - the centre panel has two layers, with an opening at one end. (I put a piece of card inside, otherwise you can't see the stitch pattern clearly.) And the stitch pattern in the centre is clearly Print o' the Wave, but with the zigzag trellis part of the pattern wider than usual. (Though I doubt that the knitter called the stitch Print o' the Wave, and probably didn't think of it as a Shetland lace pattern.)
In detail, the pattern is not the same as the one published by Mrs Gaugain - as well as the trellis part being 2 stitches wider, the edge is different, and where the two rows of decreases converge, there is a 3-into-1 decrease, whereas Mrs Gaugain has consecutive knit-2-together decreases. But like Mrs Gaugain's pattern, all the decreases are done as knit 2 together, as you might be able to see from the close-up
It's a beautifully knitted piece - though as you can see from the close-up, at that scale it's not completely even. I think that's allowable. Perhaps the stitches have stretched a bit in the years since it was knitted. It's far more accomplished than anything I could attempt anyway. And it's wonderful to have a knitted example of Print o' the Wave from the 1800s, as well as published patterns.