The pitch circle diameter (PCD) of a gear is a vital measurement when using gears. When you mesh two gears together, the teeth need to mesh to a precise distance, if too deep then the teeth will bind and wear, too shallow and you will get excessive back lash and risk damage to the teeth.
Burping gas that smell strongly of rotten eggs is actually indicative of the presence of sulfur in our stomach. This is the reason why this type of burps is commonly known as sulfur burps. The smell of sulfur burps or rotten egg burps usually comes from the presence of hydrogen sulfide.
What does the phrase America when will you send your eggs to India mean? It refers to the famine in India at the time (which was helped with the Green Revolution a few years after the 1956 referenced in the poem). What does it mean if you call someone 'a good egg'? In 1920s slang, an egg was just a person.