Show Aeroplane Propellers t Selected ash which which h is both stron strong and light and will not split under vibration or ox shock or buit built bult up layers layers lay lay- ers err of spruce with mahogany centers are are the materials with which h the th propellers prop pro pro- pellets p llers of or aeroplanes such as are being being being be be- ing used In the European war are con can ted The framework of the machines machines machines ma ma- chines too is generally made generally made of or wood spruce being much used on account of its straight grain and freedom freedm from rom I. I hidden defects |