The weather has broken at last. Then again, this was only to be expected: this is Britain, after all.

I discovered it was raining earlier this morning when I went to put out the recycling. I didn’t check the weather first and was wearing only a jacket and slippers over my sleeping clothes. In this garb I walked straight out into a rain shower and puddles!

Mylne Street

This afternoon, we went out for exercise and our usual visit to Myddelton’s. On the way I took the above photo, looking down Mylne Street with St Mark’s Church in the background. You can see how grey, damp and unappealing it is!

The Off-Licence in Amwell Street

We crossed through Claremont Square into Amwell Street. On the corner of Amwell Street and Inglebert Street stands the off licence. It has always specialized, as the name suggests, in drinks but sells enough food products for it to remain open during lockdown. I have so far never stepped inside.

While Tigger negotiated the purchase of coffee, I stood outside the deli, taking in the scenery, as is my wont.

Lloyd Baker Street

Myddelton’s is on a corner of Amwell Street with Lloyd Baker Street which you can see in the above photo. You might wonder whether the “Lloyd” in the name of Lloyd Baker Street has anything to do with the “Lloyd” of Lloyd and Son’s Dairy on the opposite corner. (See A few spots of rain.) As far as I know, the answer is no. Its name derives from the fact that it runs along one edge of the Lloyd Baker Estate.

It seems that in the late 17th century, land that had belonged to the Knights Hospitallers came into the possession of a Dr William Lloyd, then Bishop of St Asaph. At one point, the good bishop was committed to the Tower but survived, being acquitted at his subsequent trial. In 1775, his grand-daughter Mary married a vicar named William Baker, the estate being part of her dowry. Thereafter it became known as the Lloyd Baker Estate and conferred its name on this street.

The rain has cooled things down and today’s temperature stands at a meagre 8° C (46.4° F or 281.15 kelvin) which, according to my weather app, “Feels like 6°” (42.8° F or 279.15 kelvin). My “spring and autumn jacket” has had to be replaced with my winter coat. According to the meteorologists, we can expect a week of this unpleasant cold dampness.

Just as well we are not planning on taking any trips, eh?

In my recent post Fahrenheit and Celsius, I concentrated on the relationship between these two temperature scales and how to convert from one to the other. Then a reader made a comment that introduced the Kelvin scale. This set me thinking about the origin of these various scales and so I of course looked them up on the Internet. In case you are interested in what I discovered, here is an outline of my findings.

For such uses as weather and domestic temperatures, Fahrenheit is still popular in the US and certain other parts of the world but Celsius (also known as centigrade, with either a ‘c’ or a ‘C’) is now the most widely used.

The Fahrenheit scale was devised by the German physicist Daniel Gabriel Fahrenheit (1686–1736). You can tell that he was a scientist and not a layperson by the way he chose the foundation points for his scale.

He set the zero point as follows (I am quoting from Wikipedia’s Fahrenheit scale): “The lowest temperature was achieved by preparing a frigorific mixture of ice, water, and a salt (“ammonium chloride or even sea salt”), and waiting for the eutectic system to reach equilibrium temperature. The thermometer then was placed into the mixture and the liquid in the thermometer allowed to descend to its lowest point. The thermometer’s reading there was taken as 0° F.”

Fahrenheit then chose 30° for the temperature of the freezing point of water and 90° for the normal temperature of the human body. However, as he had already selected 212° as the boiling point of water, the other two had to be revised to 32° and 98.6°, respectively.

I am tempted to say that commmon sense came back into the picture at the hands of Swedish astronomer Anders Celsius (1701–1744). He chose 0° C for the freezing point of water and 100° C for its boiling point. Beyond that, there is not much to say about the Celsius or centigrade scale: it is simple and elegant.

There the matter might have rested (and for most folks, it still rests) but for William Thomson, 1st Baron Kelvin (1824–1907). Kelvin’s idea was to set the zero point at the lowest possible temperature, commonly referred to as absolute zero. The second calibration point was set at what is called the triple point of water, that is, the temperature at which water can exist simultaneously in a solid, liquid and vaporous state. The number he placed on that was 273.16. The exact definition of absolute zero is quite technical and I will not attempt to reproduce it. You will find a description in numerous sources online, including Wikepedia’s Kelvin.

I will just point out that one does not speak of “degrees kelvin” but simply of “kelvin” (small initial letter). Thus water freezes at 273.15 kelvin and boils at 373.15 kelvin. The difference between freezing and boiling is 100, as it is on the Celsius scale.