"Max Demian" wrote in message
...
The "gas marks" correspond to specific temperatures in 25 Fahrenheit
degree increments:

°F Gas Mark

225 ¼
250 ½
275 1
300 2
325 3
350 4
375 5
400 6
425 7
450 8
475 9

Ah, I've learned something. I never knew it was a linear scale - that the
difference between 1 and 2 was the same as between 8 and 9.