Proper Use Of Single Quotes & Sayings

Artificial flight may be defined as that form of aviation in which a man flies at will in any direction by means of an apparatus attached to his body, the use of which requires personal skill. Artificial flight by a single individual is the proper beginning for all species of artificial flight, as the necessary conditions can most easily be fulfilled when man flies individually. — Otto Lilienthal

Animals when in company walk in a proper and sensible manner, in single file, instead of sprawling all across the road and being of no use or support to each other in case of sudden trouble or danger. — Kenneth Grahame