i wondere about that for years, and after asking phil about it, i had to disagree with his arithmatic. to me, the average gradient is the SBR/ NDR, which is 1.2@ grade 2. consequently, a 'normal gradient is7*0.3/1.05 or 1.2/2.1=0.57. i know fred newman thinks this is too contrasty, but i can't see a flaw in my logic.(see the attached for details)