Plenty of info available about the Swiss watches by Aeby that were finished and cased by Dietrich Gruen as the first Columbus watches 1876+. What is not clear to me is why they are described as U.S. case sizes as well as Swiss ligne sizes. One of the most popular is shown here with couple of seller's photos. Original case, dial, and so called 18s movnt. in American 18s case by Essex Columbia front and back screw case perfectly fitted with set lever and smooth stem winding although keywinder model. 13080 indicates about 1880. Very nicely finished movemnet, far better looking than Gruens early designs, I found with a filler ring in the case indicating probably 19+ ligne not 18s. I have been sincerely told this movement fits directly into 18s case. 13080 would be loose. Original dial is 45 mm and larger than mvnt. plate. So I believe these Aeby movements were not Gruen design except for using his 1874 patented safety pinion, as all U.S. makers eventually did. As a Gruen collector glad to have this still nicely running Gruen endorsed unpopular cheap Swiss antique. The dial is in the then current finest Swiss watch stye with skinny Roman numbers and big seconds scale. Sometimes called a Jurgensen dial. I have one about same age 1877 shown here. Gruen always tried to do classy stuff. The CWC marked dial is a durable porcelain on copper plate. Typical of the best. Took a severe shock at 6 on the dial without cracking elsewhere.