Complex sentence: With the upcoming centenary of flight, a new effort was made to find the lost work, and some correspondence was found in a private American collection, from this it was possible to discern the general direction of his plans and the basis of his design.
Split into simpler sentences: With the upcoming centenary of flight, a new effort was made to find the lost work, and some correspondence was found in a private American collection. From this it was possible to discern the general direction of his plans and the basis of his design.