Much has been written re the long term temp variation of the climate but
as it appears were talking about around 1 deg C change over quite a long
time, pre industrial era, just how absolute accurate where the
thermometers in use?.

Course these days there are some very accurate ones around but back then
in the 1800's how accurate was a standard one back then anyone any
idea?.

Lets not take into account as to where the measurement was made either
in town out in the country at the sea side etc, but the gear in use to
measure?.

--
Tony Sayer


Man is least himself when he talks in his own person.

Give him a keyboard, and he will reveal himself.

On 27/06/2019 09:23, tony sayer wrote:

Much has been written re the long term temp variation of the climate but
as it appears were talking about around 1 deg C change over quite a long
time, pre industrial era, just how absolute accurate where the
thermometers in use?.

Probably pretty good if designed for the purpose.

Essentially temperatrurre was *defined* buy mercury thermometers.

That is 50C is the difference in length of a mercury column half way
beytween the boiling pint at seal level, and 1000mb, and the freezxing
point of water.

Unless the column was not constant diameter, this is a pretty good estimate.

Secondly averaging 100 thermometers all measuring the same things, nets
yuou a very much higher accuracy assuming te thermometers are all
randomly inaccurate.

HOWEVER the bad news is that often and to this day, the 'average' daily
temperature is talen as beiing the 'average' between the maximum and
minimum temperatures recorded in a single day.

This tends to be higher than the true average, as sunlight and
temperaure peaks quite sharply around midday and a little after. And
will peak higher in the vicinity of concrete, asphalt and other man made
materials.

Utbaisation also tends to incerase temperatires genuinely overall as
well as te peak.



Course these days there are some very accurate ones around but back then
in the 1800's how accurate was a standard one back then anyone any
idea?.

Ive got a mercutry thermometer in my victorian or edwardiam barometer
andd I'd say its accutrate to quarter of a degree or so, How well
calibarted is another matter, but it tends to agree will what the local
airfields are reporteing on the internet



Lets not take into account as to where the measurement was made either
in town out in the country at the sea side etc, but the gear in use to
measure?.

Well one should. Because the issue is less how inaccurate the
thermometers were, but how they were utilised.



--
Any fool can believe in principles - and most of them do!

"tony sayer" wrote in message
...

Much has been written re the long term temp variation of the climate but
as it appears were talking about around 1 deg C change over quite a long
time, pre industrial era, just how absolute accurate where the
thermometers in use?.

Very accurate with the max min thermometers used in stevenson screens
when they were still read manually 3 times a day. But the other problem
is that so many of them were where suburbia encroached and the usual
heat island effect made the accuracy of the thermometer itself irrelevant.

Course these days there are some very accurate ones around but back then
in the 1800's how accurate was a standard one back then anyone any idea?.

Those were just as accurate as they are now.

Lets not take into account as to where the measurement was made either
in town out in the country at the sea side etc, but the gear in use to
measure?.

On 27/06/2019 09:23, tony sayer wrote:

Much has been written re the long term temp variation of the climate but
as it appears were talking about around 1 deg C change over quite a long
time, pre industrial era, just how absolute accurate where the
thermometers in use?.

Course these days there are some very accurate ones around but back then
in the 1800's how accurate was a standard one back then anyone any
idea?.

By about 1850 Negretti & Zamba had perfected weather thermometers that
were almost as good as the ones we have today. Their centenary catalogue
is online. Their best antique kit sells for good money at auction.

https://web.archive.org/web/20110719...retti_cent.pdf

Fitzroy was instrumental in getting their kit widely distributed and
used to help try and save lives at sea by warning of impending storms.

You can find complaints from the astronomer royal about the failings of
earlier kit (mostly failure to automatically record data reliably rather
than of calibration). Calibrating between melting ice and boiling water
was fairly reliable if you measure the atmospheric pressure.

https://www.ebay.co.uk/itm/VICTORIAN...AOSwZVpck~i r

Lets not take into account as to where the measurement was made either
in town out in the country at the sea side etc, but the gear in use to
measure?.



--
Regards,
Martin Brown

On Thu, 27 Jun 2019 20:12:25 +1000, cantankerous trolling geezer Rodent
Speed, the auto-contradicting senile sociopath, blabbered, again:


Very accurate with the max min thermometers used in stevenson screens
when they were still read manually 3 times a day. But the other problem
is that so many of them were where suburbia encroached and the usual
heat island effect made the accuracy of the thermometer itself irrelevant.

I wonder more how the heat is affecting your senile head, senile Rodent!


--
Marland answering senile Rodent's statement, "I don't leak":
"That¢s because so much **** and ****e emanates from your gob that there is
nothing left to exit normally, your arsehole has clammed shut through disuse
and the end of prick is only clear because you are such a ******."
Message-ID:

On 27/06/2019 10:49, The Natural Philosopher wrote:
That is 50C is the difference in length of a mercury column half way
beytween the boiling pintÂ* at seal level, and 1000mb, and the freezxing
point of water.

Tide, IN, OUT or midway though ?.

On 27/06/2019 11:37, Andrew wrote:
On 27/06/2019 10:49, The Natural Philosopher wrote:
That is 50C is the difference in length of a mercury column half way
beytween the boiling pintÂ* at seal level, and 1000mb, and the
freezxing point of water.

Tide, IN, OUT or midway though ?.

The seals dont care as long as the pints are boiling.:-)

Midway of course. We were very good at mean sea level, being seafarers,
back in the 1800s

Remember mercury barometers and mercury thermometers allowed all these
things to be tied together.




--
Socialism is the philosophy of failure, the creed of ignorance and the
gospel of envy.

Its inherent virtue is the equal sharing of misery.

Winston Churchill