cycles to hertz - when?

[Roger Hayter]

Of course the micron still survives despite abolition. It took me a long time when first studying microscopy to realise it was a synonym for the micrometre, I sort of assumed it must be different by a factor of

1. It has the twin advantages of saving two syllables and not being mistaken for an instrument when reading quickly.

[NY]

For any given thickness of fog there is a large range of distances between when you can first see one fog light ("there is a vehicle in front of me, unknown distance away from me") and when you can see both tail lights ("ah,

*now* I can work out how wide the vehicle appears to be and therefore (and this is the critical bit) how far away from me it is").

In other words, having two lights allows you to work out what the safe distance is that you need to keep - which will be further away than you'd follow the vehicle in clear conditions.

[NY]

So a centigrad would be an incredibly small unit. I suppose if 100 grads are equivalent to 90 degrees in a right angle, then a centigrad would be of a similar order of size to a minute. In other words, probably not in daily usages, but used in engineering and navigation, as for the second.

Did the French actually produce marine maps marked with latitudes and longitudes in grads, centigrads and 10^-4 grads (what's the prefix for

10^-4 - decimilli?) from some meridian - presumably through Paris as that was a close contender to Greenwich for the worldwide longitude meridian.

Bloody hell! I was joking when I said that the prefix for 10^-4 was decimilli, on the grounds that I couldn't find anything that mentioned this odd power, so I invented something that was logical. Now I've found a site which says that it really is decimilli; likewise 10^-5 is centimilli.

[Terry Casey]

The architypal London Transport RT bus was exempted from the

1958 law and retained its one rear and one brake light arrangement on the offside (the brake light was originally amber but later changed to red.)

What is amazing about this is that this wasn't confined to the red Central area fleet but also included the extensive green Country bus fleet which covered vast areas of the Home Counties until 1970, with many routes on unlit country roads. They could alo be driven with only the nearside headlight turned on!

Many of these buses were bought both by preservationists and provincial operators but the moment ownership pased from LT, it was ilegal to drive them on the public highway!

[Marland]

Wasn?t just the older London buses that had dispensation from some things, the later models of the 70?s and 80?s were still permitted to use the older style silver letters on a black background style of registration plates for many years after other vehicles had to have reflective Black on White at front ,Black on yellow at rear.

GH

[Terry Casey]

The plate style depends on the registration date and applies equally to all vehicles as you can see on older cars and other vintage vehicles of any kind.

However, a lot of ex LT Routemasters were bought by Scottish operators who re-registerd them so they have to carry new style plates

There is alarge selection of vehicles with old style plates at

As you can see from the descriptions, many of them are currently MOT'd taxed{1] and insured but the pictures show that they still carry the original plates.

[1] Although the tax on older vehicles is now free, they still have to be 'taxed' although, of course, they no longer get issued with tax discs.

[Marland]

Which is what I was getting at,

Vehicles registered from sometime in 1973 had to have the reflective style though they could have been used voluntary from 1968.

However London Transport or whatever it was at the time seemed to still be allowed to use the White on Black for a few years later such as on this

1979 vehicle. or this on which shows that they still were using the old style into the early 80?s. So it cannot have applied equally to all vehicles . Incidentally I see due to a quirk some vehicles that had to have compulsory reflective from 1973 can now have white on black due to them moving into the historic taxation class which allows non reflective plates.

GH

[tony sayer]

Now what were you doing with 1 K on 27 M/cs?...

JOOI what gave more Pout a PL519 or an 807

[Terry Casey]

Interesting - I didn't realise it went that far back.

The London Transport Executive (under the GLC from 1970 to

1983

I hadn't realised that, either

[Lee]

Wasn't me and sadly, said person is no longer around. People living around here at the time will not have failed to notice the Sigma IV said person also used. Though not with that 1Kw linear. Mostly they used a Bremi 200W with that.

That incident was a stupid experiment with a Firestik. Why? Who the hell knows it was a very long time ago and we were too young to know much better.

I don't know, I guess the PL509/519 were popular at the time just becuase they were so easily available.