At one point in time, it would have been appropriate to describe the tremendous interest in vintage chronographs as a phenomenon of sorts, but those days are now long behind us. Today, vintage chronographs are the central focus of collectors both new and old, and thanks to the efforts of prominent tastemakers, they now make up one of the largest portions of the market for collectible timepieces. The shift of interest towards these watches can also help explain why individuals are becoming more inquisitive than ever before about the minuscule details found on their watches, and in vintage chronograph collecting, there is a seemingly endless amount of details one can immerse themselves in.
Of all the details that you’ll find on the dial of a vintage chronograph, it could be said that some of the most intriguing intricacies are the dial-surrounding scales that were formerly used to perform calculations. In many cases, these scales would have ultimately determined the target market for a particular watch and their legacy for years to come. Let’s now take a closer look at the various types of scales found on our favourite vintage chronographs and how one goes about using them.
Out of all the scales used on chronograph dials, the tachymeter is by far the most commonly seen. This is because it’s useful in a number of different day-to-day applications. Tachymeters are primarily used to calculate travelling speed; this is done by dividing the number 3,600 (the number of seconds in an hour) by the amount of elapsed time. Alternatively, a tachymeter can be used for calculating distance travelled. However, to do this one must know the speed at which they’re travelling and maintain that speed throughout the process of measuring distance.
As one would expect, tachymeters are traditionally found on watches designed with motorsport in mind like the Rolex Daytona and Omega Speedmaster. Having said that, its presence on a particular watch doesn’t necessarily determine the watch’s intended purpose since the tachymeter is highly functional and versatile.
Seeing as wrist-mounted devices for the health conscious, such as the Apple Watch and Fitbit, are all the rage at the moment, it’s worth taking a look at what could be considered an ancestor of these newer gadgets — a Pulsometer-equipped chronograph. Watches featuring this sort of scale are believed to have first been made in the 1920s. Then, they served as critical tools for medical professionals who wished to accurately take a patient’s pulse with ease.
Most pulsometer scales are set to calculate pulse based on 15 or 30 heartbeats. So, to determine a pulse, all one must do is start the chronograph and then stop it at the patient’s 15th or 30th heartbeat. Wherever the second hand stops clearly indicates the frequency of beats per minute. Knowing how simple this scale is to use only makes watches like the early Longines 13ZN chronograph and the A. Lange & Söhne’s 1815 Chronograph (in specific versions) more attractive.
A telemeter is technically any device that can be used to collect data from a remote location. When found in scale form on a chronograph’s dial, it does exactly that. The telemeter’s horological origins can be traced back to times of war when military men needed a device capable of calculating the distance between themselves and events that could be both seen and heard such as artillery fire.
Using the principle of the speed of sound, this is accomplished by starting the chronograph when the event is first seen and stopping it when it is finally heard. In its final position, the chronograph’s seconds hand points towards the distance between your position and the event. It can be displayed in either kilometres or miles depending on the watch.
Lastly, we have the decimeter, a scale in intervals of ten used for timing to the hundredth of a minute. This scale proved to be especially useful in industrial timing and statistical analysis as it easily allows for the decimal division of time. A personal favourite watch that features a decimeter on the dials of certain versions is the Ref. 2447D Carrera by Heuer — a rare bird with timeless aesthetic.