In our modern world, a reasonably up-to-date smartphone with GPS is enough to determine your position, accurate to a few feet. But it wasn’t so long ago that people had to use astronomical navigation to determine their current location. If you want to try this method yourself, Longines has the right timepiece for you – the Lindbergh Hour Angle Watch. The watch is a tribute to aviation pioneer Charles Lindbergh, who went down in history for completing the first non-stop solo crossing of the Atlantic in 1927.
The Longines Lindbergh Revolutionizes Navigation
The flight was risky, and not just because aircraft technology was still in its infancy back then. At the time, Lindbergh had not yet mastered astronomical navigation and also did without radio navigation. He relied exclusively on what’s called dead reckoning, in which you calculate your current position based on your direction of movement and speed. The problem with this method is that errors quickly add up and the pilot can wind up significantly off course. Lindbergh avoided this by using coastlines, islands, and other objects to stay on course. Lindbergh finally landed in Paris after thirty-three and a half hours, having survived a blind flight in fog lasting several hours. Still affected by his risky flight, Lindbergh began working with Longines to develop a watch that would enable safe and precise navigation. Contrary to legend, this was not Longines’ first pilot’s watch. They developed their first pilot’s watch together with Philipp van Horn Weems. Weems was regarded as an expert in navigation and introduced Lindbergh to his theories after his Atlantic flight. The Longines range includes the Weems Seconds Setting Watch, a tribute model based on the original from the 1920s. Lindbergh’s watch is heavily based on Weems’s, but adds numerous functions that make it the perfect navigation watch.
Astronomical Navigation – What Is It?
Astronomical navigation – navigation using the stars and other celestial bodies – is relatively simple in theory. You can determine your latitude – that is, how far north or south you are – by measuring the angle of the sun above the horizon when it is at its highest point. To determine your longitude – that is, your position on the east-west axis – you only need the hour angle, which indicates the time difference between the prime meridian in Greenwich and your current position. All you have to do is convert this time difference into a degree and voilà: you know exactly where you are. Unfortunately, it’s not quite that simple in practice. The time system we organize our lives around is based on the premise that every day is exactly 24 hours long. This system is generally referred to as mean solar time and allows for calculations to be made very easily. In the case of longitude that means, for example: The earth rotates 360 degrees every 24 hours, i.e., 15 degrees every hour. So far, so good. The problem, however, is that not every day is 24 hours long. This is where real solar time comes into play, which sometimes deviates significantly from mean solar time. This is due to the fact that the Earth does not always orbit the sun in the same way, but wobbles slightly. The difference between real and mean solar time is what’s called the equation of time. You can look up the equation of time for a specific date in an astronomical almanac (or online).
How to Read the Dial of the Longines Lindbergh
The displays of the Longines Lindberg Hour Angle Watch work as follows: The hour hand shows you roughly the current hour angle on a scale with 15-degree intervals. For even more accuracy, use the minute hand. Every four minutes, the minute hand rotates by 1 degree (i.e., 15 degrees in one hour), which you can read on the outer bezel. You can get even more precise with the seconds hand. Each revolution of the seconds hand is equal to 15 degrees and therefore each second corresponds to one sixtieth of 15 degrees – i.e., a quarter of a degree (0 degrees, 0.15 degrees, 0.30 degrees and 0.45 degrees). You can also read this information on the bezel. You can account for the differences between real and mean solar time by moving the bezel. If the equation of time is positive, turn the bezel clockwise. If it is negative, however, turn the bezel counterclockwise.
An Example
It’s May 2, 2024, and to determine our current position, we first have to set the Lindbergh Hour Angle Watch to Greenwich Mean Time, which in our case is 11:42 a.m. Now we have to adjust the equation of time. According to the astronomical almanac, this is minus 3 minutes on this day, so we turn the bezel three steps counterclockwise. Now we can read the hands. The hour hand shows 165 degrees, the minute hand shows 11 degrees and the seconds hand shows 0 degrees, giving a total of 176 degrees. You can now determine your real solar time with the help of a sextant. For our example, let’s assume that the real solar time is 9:06 a.m. As real solar time does not need to be adjusted, you can move the bezel back to the zero position. Now we’ll read the hour angle from the dial again. The hour hand shows 135 degrees, the minute hand shows 1 degree and the second hand shows 0 degrees, for a total of 136 degrees. Finally, subtract the hour angle of real solar time from that of Greenwich Mean Time: 176 degrees minus 136 degrees equals 40 degrees. If the result is positive, as here, you’re west of Greenwich. If the result is negative, you’re east of Greenwich. So we are 40 degrees west of Greenwich over the Atlantic.
Summary
In the age of GPS, watches like the Lindbergh Hour Angle watch have little practical value. Nevertheless, it’s a fascinating piece of technology and the perfect conversation starter. On Chrono24, you will find the Longines Lindbergh Hour Angle watch in numerous versions at prices ranging from around $1,000 to $4,600.
