"Max Demian" wrote in message
o.uk...
On 22/02/2019 13:01, NY wrote:
"Max Demian" wrote in message
o.uk...

Do they still use gas marks rather than degrees Celsius in gas ovens? I
haven't seen an explanation why gas ovens use these arbitrary numbers
rather than degrees (Fahrenheit or Celsius), though I have some ideas
why it might have happened.

Yes I've never understood why gas ovens historically used arbitrary "gas
marks".

My *guess* is that gas ovens were the first to have thermostats, as it is
easy to regulate gas flow with a tap, whereas the thermostats in electric
ovens work by switching the power on and off - hard to do without sparking
the contacts with the switches at that time. (I'm thinking of the 1930s
here.) I imagine electric ovens would have had a high/medium/low switch
and a thermometer in the door like the later Baby Belling table top
cookers.

Perhaps the makers of the first thermostatic gas ovens lacked confidence
in their accuracy; or it was thought that degrees Fahrenheit would confuse
housewives and simple numbers would be easier for them. In any case, they
screwed up as presumably the original scale went from 1 (275 °F) to 9 (475
°F) and they realised that they needed an extra two marks for lower
temperatures: ½ (250 °F) and ¼ (225 °F).

Yeah, I bet it was done with numbers to keep it simple
when they were free to do anything they liked given
that theirs was the only common product around
that allowed you to set the oven temp. The only
alternative was the Aga style ovens with no control
knob doing anything, just a mechanical thing.

This is all guesswork, however.