Vector Analysis and Quaternions #263291

Every proposition about quantities in space ought to re main true when restricted to a plane; just as propositions about quantities in a plane remain true when restricted to a straight line. Hence in the following articles the ascent to the algebra of space is made through the intermediate algebra of the plane. Arts. 2 — 4 treat of the more restricted analysis, while Arts. 5 — 10 treat of the general analysis.