The link from the pin is broken, but the caption says that it's a boy's mitten from ca. 1858-1863, which is about fifteen years too early, but since mitten design hasn't changed much in the last 70 years (compare this pattern from 1940 to this pattern from 2007, I think we can safely say what they were knitting in 1858 probably isn't too far off from what Ma was knitting in 1874.
So what can we deduce from this historical sample?
Starting at the bottom: there's no obvious edging - no garter trim or ribbing to keep the bottom edge from curling, and while the caption says that it has an orange knit lining, it's not visible in the part of the picture that shows the inner edge of one mitten, but it is definitely stockinette on the inside, too, so the edge is probably faced - folded up to the inside, and sewn down, or - more likely - joined to the live stitches as the knitter worked up the hand. You can just about see the line where the double thickness of the folded up edge ends, about an inch from the bottom. The mitten on the right side of the picture looks like it might have some decreases in the cuff, adding to the flared effect, but not enough for me to bother trying to duplicate it.
The increases for the thumb gusset are unusually placed. Instead of new stitches always being placed on the outside of the previous increases - growing into the thumb, the new stitches are placed inside the previous increases - growing out into the hand. It makes it less intuitive which stitches to divide for the thumb. The number of stitches between the increases is hard to measure, possibly four or five?
Decreases are done like a flat sock toe rather than spiraling. Probably a three-needle bind-off on the right-side mitten, the one in the left side of the picture looks as though it might have a drawn-through bind off.
The gauge looks like it might be 8-10 stitches to the inch, but the resolution makes it difficult to count.
If anyone knows anything about the original source or how to find out more about these mittens, please let me know in the comments!