Complex sentence: On 24 September 1942, Wilhelm took the ingot to Spedding at the Metallurgical Laboratory in Chicago and presented it to Compton, whose first reaction was of disbelief.
Split into simpler sentences: On 24 September 1942, Wilhelm took the ingot to Spedding at the Metallurgical Laboratory in Chicago. They then presented it to Compton, whose first reaction was of disbelief.