Charles Lindbergh helped design the Hour Angle with Longines with the purpose of aviation in mind. The Lindberg Hour Angle is one of the most iconic watches produced from Longines and is also known as the Weems Second Setting watch. The Hour Angle watch was designed specifically to work with the Weems system of navigation. Philip Van Horn Weems was a United States Navy officer who was an inventor of navigational instruments and methods of navigation. The main purpose for this model is to help aviators navigate and determine where they are (Longitude) at any given time during flight. The Hour Angle watch features a rotatable center disc, controlled by the crown, and rotatable bezel that the user can operate to achieve this. To set the time on this watch one must pull out the crown and press the button directly next to the crown to move the hands, if not the crown will just rotate the center disc. This system is commonly found in pocketwatches as well as the hinged case back and dust cover. These Hour Angle watches are hard to come by and have serious historical significance, making them highly sought after by collectors.