HAU (German:Hamburg Amerikanische Uhrenfabrik) or HAC (English:Hamburg American Company) was formed in Germany in 1873 by Paul Landenberger and Phillipp Lang. The initial company was known as Landenberger & Lang Uhrenfabrik and had a trademark, a steamship with the words 'In God We Trust'. Paul Landenberger, son in law of Erhard Junghans, worked at Junghans for several years before starting up this new company. The company was involved in the production of clock movements, clock parts, dials, and cases for all types of clocks. Most of these products were sold to the trade as they were not in the business of selling finished clocks, it seems.
The company changed their name to Hamburg Amerikanische Uhrenfabrik and Hamburg American Clock Company (HAC) in 1883. The famous crossed arrows became their trademark in 1892, at which time the company had aspirations toward the sale of finished clocks to the export market, particularly to Great Britain and North America. They were involved in the production of mantel, Longcase, wall, ship, and specialized industrial clocks, and they were still supplying components such as decorative parts dials cases, parts, and hardware for the clock industry. The company was a major producer of clocks in Germany, with 1300 employees in 1910. They produced many types of clocks from alarm clocks to ‘Ticket clocks' to wall and mantel striking and chiming clocks. In 1926 the company went into a cooperative with Junghans and in 1930 they finally merged with Junghans.
Source:
http://www.rusted.free.fr/carrillon.html