Longines
The Greatest Watch You’ve Never Heard Of: Longines Nonius
Longines
The Greatest Watch You’ve Never Heard Of: Longines Nonius
Horology is not your normal competitive activity. The cancellation of the Swiss chronometer trials at the end of the 1960s put paid to the “Olympics of accuracy” and a recent attempt to revive them in the Concours de Chronométrie has been hampered by the severely limited field of entrants. Certified accuracy may be out of fashion, but healthy competition in other areas seems to come in waves. Right now, it is thinness where the records are falling, but a few short years ago it was chronograph frequency that came under the spotlight with ever increasing claims for accuracy.
The frequency of a movement indicates how finely the escapement slices up time to be displayed by the chronograph seconds hand. A Speedmaster with a 321 caliber beats away at a relatively sedate 2.5 Hz, meaning each beat is 0.2 of a second. Early 7750 calibers ran at 3 Hz with each beat a rather awkward 0.167 of a second. Later 7750s and the Rolex Daytona’s caliber 4130 jog along at a lively 4 Hz, allowing a display of 0.125 of a second.
In 2010, Breguet launched their reference 3880 a chronograph with a 10 Hz escapement allowing a display of 0.05 of a second. In 2011 TAG Heuer blew the competition away with their Mikrotimer, running at an incredible 500 Hz and capable of showing 0.001 of a second. Not content with this, the following year they doubled the frequency to 1000 Hz with their Mikrogirder, displaying 0.0005 of a second – a record that stands to this day.
The Vernier scale is a way to take a more accurate reading of a point between two marks on a scale. The mathematics is complex but the use is simple; the fraction between the two marks, where the tip of the chronograph hand has come to rest, is found by looking along the mobile scale for the best alignment of a mobile mark with one on the dial. This then gives the tenths of a second reading. The mobile scale is short by one tenth per increment compared to the dial scale. For each tenth of a second the second hand is beyond a dial seconds marker, the corresponding number along the mobile scale will be shifted into perfect alignment. The human eye is incredibly good at judging alignment compared to distance travelled across a small gap and in this way the Vernier gauge acts as a magnifying glass for the hard-to-read seconds track of the dial.
Why a gimmick? The answer lies in the escapements of the two movements. The Longines calibre 30CH ran at 2.5 Hz – giving five beats per second and so five positions that the seconds hand could land in. Having a resolution of 0.1 seconds is therefore useless until the advent of 5 Hz wrist chronographs such as the Zenith El Primero. Even worse was the upgrade to the Cal. 332, this was running at 3 Hz, giving six beats per second. With a Vernier scale set up to read tenths of a second, the only alignment possible would be at the 0.5 seconds point, all the rest would fail to line up at all.
The outlandish design had one further flaw, the weight of the Vernier scale itself. Positioned at the tip of the seconds hand, this extra weight created large amounts of additional torque as the chronograph was reset. This meant that the hand was prone to working loose or falling off altogether.