FORE:It was a few days later before Hetty thought of her promise to Balmayne. It was a fine bright afternoon with a strong sunshine, so that even the deserted house in Lytton Avenue looked almost cheerful. With a feeling that she might have been taken for a burglar or a house-breaker, Hetty let herself in.(1.) What does the term "machinery of transmission" include, as applied in common use?(2.) Why cannot direct comparisons be made between shafts, belts, and gearing?(3.) Define the relation between speed and strain in machinery of transmission.(4.) What are the principal conditions which limit the speed of shafts?