Hamilton introduced a variety of new models in 1930 - many of which are "holy grails" for Hamilton collectors. It seemed that the company cut it's wrist watch teeth on the geometrics of the 1920's but really hit it's stride in 1930 and beyond.
One of the very nice "entry level" solid gold models introduced in 1930 was the Langley.
The Langley was produced through 1934. Originally it featured the 987 movement but eventually was marketed with the similarly sized, 19 jewel 979 (or 979F) movement that was used in the other solid gold models.
The Langley was produced in 14K yellow gold and 14K white gold. There are about twice as many white versions as yellow versions. There are even a small handful of 18K Langleys manufactured for Tiffany with Tiffany branded dials. You'll also occasionally find specially engraved "ask the man who owns one" Langleys produced for the Packard Motor Car Company.
The Langley came with a luminous dial as well as a less common Raised Gold Figure dial with applied solid gold numerals. Hamilton would later call this an Applied Gold Numeral dial.
The Langley can be found in a three-piece case as well as a two-piece case. In the three-piece case the movement is held in a center section that hinges into the case back - and the case back snaps into the front bezel.
I've had the pleasure of working on a couple of Langleys for other collectors I know. Here's a yellow gold version... notice the female spring bars needed for this type of case. These types of bars are used when the case has pins instead of holes. The bars go over the pins rather than sticking into holes in the bezel lugs.
Here's what a three-piece case looks like with the 19 jewel 979 movement inside the center section that is hinged into the case back.
And here's a white version of the Langley.