The inventor's demonstration

An original fiction passage set in the nineteenth century.

Mr Alden waited until every guest was watching before he pulled the velvet cloth from his machine. A polished metal hand stood above a tray, its fingers curled neatly around a porcelain cup. “You will observe,” he announced, “that it performs the most delicate task without hesitation.” He turned the handle with a flourish.

The hand rose smoothly, carrying the cup towards an empty saucer. Halfway across, it stopped. Mr Alden gave a small laugh. “A pause for your admiration,” he said, and forced the handle through another turn.

The machine shuddered. The cup struck the saucer, split at the rim and released a brown stream across Mr Alden's plans. “A little stiffness,” he murmured. As he reached for the stopping lever, the metal fingers closed around his cuff. Nobody laughed. His assistant stepped forward and freed him.

Mr Alden folded the stained plans until the spreading mark disappeared inside them. He covered the machine without inviting his guests to observe anything further.

Analyse how the writer uses language and structure to reveal the change in Mr Alden's confidence during the demonstration. Support your answer with references to the passage.