WW2 RAF Smiths 1/10 VC Stopwatch

A good military 1/10 Second VC stop watch, with 6B/ issue marks for the RAF, in collector grade condition and working order.

For many years the meaning of the "VC" marking on these stopwatches has dogged collectors, with some fanciful suggestions being proffered. However, the real meaning of this code can now be revealed.

Military watch collectors may have noted that there are in fact two versions of this stopwatch; one is the 1/5 second VC 2530 and the other is the 1/10 second VC 2534. The "VC" simply means "Vernier Constant" and the other digits are just the inventory numbers that list the item location in a military store.

So, what is a Vernier Constant? Also known as the "least constant", the VC is the smallest mesurement that can be read by the instrument. You're probably familiar with Vernier calipers and have noticed many lines of measurement on their linear scale, or on a slide rule, well typically, these will also identify whether they are part of a traditional, imperial or a metric measurement system and what the smallest measurement that can be read from it. This will usually be expressed as a fraction. These small intermediate divisions are what constitute the larger unit, and it is these that are expressed as the least "constant". They allow an engineer to precisely measure to a more exacting degree to a nearest number or decimal fraction.

In respect of these stopwatches, the Vernier Constant for this timer is a fraction, one tenth of one second. The watch is therefore calibrated to provide a reading to within 1/10, or 0.1 of a decimal second. 1/10 is the constant.

These watches probably had a multitude of uses in the engineering sector of the RAF, but as this example has a rare 6B reference, this puts the watch in the realms of "flying equipment". Logically, it might well be that this Smiths was being used as a version of an aircraft ground speed calculator. This isn't without precedence as other fast running timers had previously been used for this purpose during WW2. Postwar, the requirement to time faster jets with greater precision became a more pressing matter.

If you wish to share this information, please do but I respectfully ask that you link a credit to this website. As for the small broad arrow that forms part of the F mark? If you can help, I would be interested to know.

VC = Vernier Constant

Code: 51790