"John Hall" wrote in message
...
In article ,
Col writes:
I recall asking a similar question some time back and was told that
the early readings were derived from a tiny handful of sites (hence
their accuracy to only 1 degree)

I think that you're thinking of the claimed accuracy of the earliest CET
monthly averages to 1F, which equates to roughly 0.5C.

In the very earliest years (to 1670) the figures are given in whole degrees only
so surely that is an accuracy to 1 degree?
From 1671 to 1698 it is half a degree and thereafter 0.1C.

Col
--
Bolton, Lancashire.
160m asl.
http://www.reddwarfer.btinternet.co.uk
http://www.reddwarfer.btinternet.co....rPictures.html

In article ,
Col writes:

"John Hall" wrote in message
...
In article ,
Col writes:
I recall asking a similar question some time back and was told that
the early readings were derived from a tiny handful of sites (hence
their accuracy to only 1 degree)

I think that you're thinking of the claimed accuracy of the earliest CET
monthly averages to 1F, which equates to roughly 0.5C.

In the very earliest years (to 1670) the figures are given in whole
degrees only
so surely that is an accuracy to 1 degree?
From 1671 to 1698 it is half a degree and thereafter 0.1C.

You're probably right. My memory was that the whole series - including
the extension back in time as far as 1659 - was originally produced by
Manley using degrees Fahrenheit, but I may well have been wrong in that
and or the precision may have subsequently been revised.
--
John Hall
"One half of the world cannot understand
the pleasures of the other."
From "Emma" by Jane Austen (1775-1817)

A bit more on low maxima in London. According to this page on Trevor
Harley's excellent website:

http://www.personal.dundee.ac.uk/~ta...in_january.htm

the three coldest January days in London on record are, in chronological
order:

8th January, 1841: max of -8.3C at Greenwich
4th January, 1867: max of -8.3C at Camden Square
12th January, 1987: max of "reportedly" -9.1C at Warlingham and -8C
"across large parts of the south"

Too much notice should not be taken of the tenths of a degree in the
first two values, as I suspect that they are converted from values
originally read to the nearest whole degree Fahrenheit.

Obviously 1740 is likely to have produced at least one colder day, as
may some other early winters, but accurate instrumental readings are
lacking.
--
John Hall
"One half of the world cannot understand
the pleasures of the other."
From "Emma" by Jane Austen (1775-1817)

In article ,
John Hall writes:
the three coldest January days in London on record are, in
chronological order:

8th January, 1841: max of -8.3C at Greenwich
4th January, 1867: max of -8.3C at Camden Square
12th January, 1987: max of "reportedly" -9.1C at Warlingham and -8C
"across large parts of the south"

One other point. The two 19th century figures won't have been obtained
from a thermometer in a Stevenson Screen. However if, as is likely, they
occurred in a strong easterly wind, then I wouldn't expect that to make
any significant difference. (Not that I'm an expert.)
--
John Hall
"Sir, I have found you an argument;
but I am not obliged to find you an understanding."
Dr Samuel Johnson (1709-1784)