The Watford Speedometer......a brief look at this early instrument...

If you've a motorcycle or car made from the 1930's onwards that is British, then Smiths or it's other company British Jaeger would have been the instruments fitted and available.
But prior to this, in the 1920's and earlier there were numerous instrument firms vying for your business to fit a new speedometer to your motorcycle and in the teens, your car....
Speedometers were not legally required in the UK until 1937....
So many motorcycles were supplied without a speedometer and you had to purchase one separately with the drive and cable, usually from a Factors business ( what we call an automotive or motorcycle accessory house today) ...examples are Halfords, Pride and Clarke etc....
Smiths were just one of the competitors...
So lets have a look at another of them....
The Watford speedometer....well they made tachometers and clocks also....is one we will look at in this blog.
I've a very nice early catalogue which I've scanned and is illustrated below....
As well I have a nice example of a Watford motorcycle speedometer and have photographed it...
You'll note it has two hands...the so called "maximum hand", which stayed at the fastest speed you reached, unless you reset it with the button on the side of the case.
Perhaps this developed with police speed traps and the desire to contest any "booking"....
A 1909 Smiths catalogue I have shows "maximum hand" speedometer which had another, perhaps "bizarre" use...
These were able to be locked and, quoting the catalogue... "allowed owners to check on any furious driving by their chauffeurs"....
Watford speedometers had nickel plated cases and as chromium plate wasn't utilised until after 1926, one can date an object.
As well the speedometer, as did many of the period, has a beveled edge glass and again these disappeared in the late 1920's....
Left click on the images to enlarge them....
As you will see they were made in Watford, North London, hence the name, by the firm North and Sons Ltd, who dabbled with magnetos also. 
The business started in 1905 but there is little reference to them after the  the Great Depression , although they were still filing patent applications for odometers and some ignition system modifications up to the mid 1930's, and the dial on the speedo I have has several patent numbers, but these I seem unable to track down......but I suspect they went under like so many other companies of the time, not surviving either the Depression or WW2.
In my time, when I was active in the instrument restoration business, I can honestly say we only worked on a few examples....
So they are rather rare, but form a nice fitment to a motorcycle of the era as an alternative to Smiths/Jaeger....
The calibration factor for this following example is 710 cable turns per mile, so they were only suitable to be driven from an open gear drive setup on the front wheel, with a large gear attached to the wheel spokes.
It may well be that the calibration factor for other earlier Watford speedometers differs from this...highly likely, as the "opposition", Smiths governor speedometers used calibration ratios from 1600Tpm to 4400Tpm...they used a letter rather than a number, so you need the specific information as to what they referred to from a Smiths repair manual...pretty hard to come by. For example "A" was 3360Tpm..."D" was 1610tpm....
The only way to ascertain the calibration ration of any speedometer is to run it on a tester to indicate 6omph and read the rpm the cable is driving it at.
This rpm is the calibration figure.
I'll run a blog on this drive system in the future....

Advert for Watford speedometer....

The Watford catalogue....