A Pantograph is the instrument that measures the amount of "wheeze" in a steam engine when stationary.
Too much "wheeze" indicates that said engine would need assistance to haul the solidified layer from off the top of a rice pudding.
I think you must be confusing Pantograph with Pantygraph, which is a wind chill meter, used to determine whether underwear would be deemed advisable when wearing the kilt.
Ask Giok.