Possible Clues:

• Boxes with energy, being thin
• Scattered here and there
• Reserve head of state, admitted, is not thick
• Son to break down, being thin
• Meagre lines finally accepted by extra
• Poles close to France, scattered
• Science's beginning to analyse lacking density
• Average results in final parts of course few and far between
• Few and far between to make a press
• Poles' employment initially thin on the ground