秤
=
平
+
禾
:
Charlie Chaplin (ch) wants to fry his cereals (禾) in a frying pan (平) in the engine's bathroom ((e)ng4). To get the quantity right he weighs his cereals with a steelyard (秤) first.
although small, a steelyard weight may tip a hundred pounds (idiom) / apparently insignificant details can have a large impact / for want of a nail the battle was lost