The gown is called a "tent style" gown in the period, but I think of it more as just a basic "A" line shape. There is no fitting done at the waist, it just falls straight to the feet. It closes with one button in the back like the originals do that I found. The main difference is the overall length, baby dresses covered the feet, but that could be by a little or a lot. On all of Asa's gowns I have opted for about 4"-6" of skirt to cover his feet, this seems like a reasonable amount that doesn't gobble up too much fabric. However, if I were making this gown again, I would make the skirts longer because I'd like them to be somewhat wider across the middle. He has wiggle room but not as much as I'd wish. Then again he will probably have outgrown it by the day after tomorrow anyway. :-)
Here is a close-up of the bodice detail, it is basically just bias strips ironed into shape and applied. However, it does give the illusion of a waistline and makes the gown somewhat more interesting than an untrimmed one.
This original gown is from the Wisconsin Historical Society and is dated 1860-1869. It would seem to be a less popular choice at the beginning of that decade but as time passed it is seen more frequently in images and surviving originals. It is basically a chemise style gown but is left uncontrolled at the waist, by contrast most 1860's gowns have a definite fitted waistline.
This image is from Godey's magazine and was published in 1871, I'm sorry that I don't have the exact month. It shows a baby in a gown very similar to the original pictured above.
This baby shoe pattern from January 1870 was found in Peterson's magazine and would be the perfect compliment to Asa's new gown. They look so easy to sew up that I'm really tempted to make him a pair!
The last image is also from Peterson's magazine, November 1870. It shows how gored the skirts could be as pictured on the little girl's dress on the top right. It also displays the sizeable bustles that were fashionable. The fashions of the 1860's with the voluminous skirts and supporting hoops give such a different silhouette than fashions a scant decade later. By the 1870's most skirts had the fullness pulled to the back creating a flat panel down the center front with the fullness taken up in bustles that would continue to increase in size. I think they are beautiful in their own way but not a practical fashion for a Country Wife.