Arnold & Son DBS Equation Sidereal – Two Watches In One

Arnold & Son DBS Equation Sidereal

Aspiring astronomers take note; today we have a special timepiece just for you. That’s right, the Instrument DBS Equation Sidereal.


The name’s a bit mouthful I know so let’s just agree to call it the DBS from here on out, ok? This incredible new piece from luxury watchmaker Arnold & Son has been created specifically for stargazers. And I mean that in the literal sense, as opposed to say something like the Geo.Graham Moon we profiled last week, which is designed more for those who like to gaze at the stars on their wrist.

So, what makes it so special you ask? Well, as the name suggests the DBS is capable of calculating and displaying sidereal time, which is essentially a measure of the rotation of the earth relative to the stars as opposed to the sun. A mean sidereal day lasts 23 hours, 56 minutes and 4.091 seconds, which is approximately 4 minutes shorter than a mean solar day. This measure of time is particularly important to astronomers, who use it to track the direction needed to point a telescope at a particular star in the night sky.

What’s really cool about the DBS however is that it can also calculate and display solar time, at the same time!

How Does It Work?

Before we go too far into the technical talk I’m sure quite a few of you are thinking that’s great but don’t we have computers for that sort of thing now? The answer to this question is of course yes, but that’s not why this timepiece was created.

You see the DBS is a tribute to two watches (Nos. 1 and 2) made by John Roger Arnold that showed mean solar and sidereal time on two separate sub-dials. The movements of these two watches, made between 1796 and 1799, featured some of the most famous inventions of the father and son team, including their thermo-compensated Z balance, expansion escapement and gold helical spring. Suffice to say, this stuff was pretty cutting edge at the time.

That’s not to say that today’s incarnation is not equally high-tech, because it most certainly is. Following their namesake’s original ideology, Arnold & Son have developed a completely new movement in-house, which features a double barrel/gear train and double balance/escapement running at different speeds, enabling the watch to display mean solar time and mean sidereal time simultaneously. The bridges, barrels and gear trains of this manual-wind marvel, known as the A&S1311, have all been arranged in perfect symmetry, as have the two adjacent balance cocks on the dial side.

Arnold & Son DBS Equation Sidereal

Sidereal time is displayed on the left sub-dial and mean solar time on the right. In addition, a sub-dial at 12 o’clock indicates the equation of both times on a 24-hour basis, which allows the user to measure the difference between mean solar time and sidereal time and to ascertain whether the time in both zones is a.m. or p.m.

The watch has a long central permanent seconds hand (for mean solar time). The two barrels are wound using the crown on the right, but sidereal time and mean solar time are set separately using the crowns on the left and right, respectively. This ensures that neither of the displays is changed or manipulated by accident.

Aesthetically the DBS exudes the brand’s typical sense of classic style, elegance and refinement are the order of the day here. The 18-carat rose gold case is a little bit large for a more formal timepiece at 44 mm but not problematically so and the unusual complication more than makes up for it. The dial is a subtle mix of silvery-white and silvery opaline and the whole package really comes together nicely on the hand-stitched brown alligator leather strap.

Arnold & Son DBS Equation Sidereal

RRP is quite reasonable at US$46,500 given that this is an in-house movement and quite a complex one at that.

Arnold & Son will also be exhibiting at SalonQP 2012 and so if you are lucky enough to be attending I highly encourage you to get along to their display and check out everything the brand has to offer.

The Final Word

As many of you know I am a sucker for symmetry, and this particular piece has got it in spades. In addition movements with a double balance and escapement are quite unusual these days, rare even – although I’m not sure that something that can be created at will can really be considered rare. Nevertheless, all these elements combined with top quality finishing and a clean, balanced dial make the DBS, for me at least, quite an attractive proposition.

Certainly it won’t suit all tastes but if your interest, like mine, has been piqued then be sure to jump over to the brand’s official website to see more:

Tom Mulraney
Tom is the founder and editor of The Watch Lounge. Together with his team he is dedicated to bringing you the best, original content you won't find anywhere else on the net.

Leave a Comment