i would be v grateful for the answer to 21d "ratio unit of quantities found in one per thousand " N?P?R ( I'm fairly confident of those letters being correct ) drawing a blank at every turn.
Also would be pleased if someone would confirm that 26a " care shown in often difficult circumstances " (4) ?E?D is HEED ???????
unit for comparing two currents: a unit for comparing two currents, voltages, or related quantities, equal to the natural logarithm of the ratio of the quantities.
Finished ! Thanks to BigDave and jimbo. I must invest in a bigger, better dictionary. My well-thumbed 1932 New English Dictionbary, which cost a fiver in Oxfam, has passed its best-before date............no mention of neper