Practical plane and solid geometry for advanced students, including graphic statics, adapted to the requirements of the South Kensington syllabus (1899)
Harrison, Joseph, Baxandall, George Albert · London Macmillan · leaf 516
N B C\ D ^B As3 B> … CHAPTER XXI GRAPHIC STATICS 396. Directed quantities.—In arithmetic and algebra weare concerned with number and magnitude. A secondimportant quality possessed by many objects and phe-nomena, and which can be made the subject of calculation,is that of having a definite direction in space.…