MENTAL MEASUREMENT.
1. Mathematics and the material sciences rest upon quantity and measurement.
THE history of science is the history of measurement. Those departments of knowledge in which measurement could be used most readily were the first to become sciences, and those sciences are at the present time the furthest advanced in which measurement is the most extended and the most exact. Mathematics is concerned entirely with number and quantity, and it has always been allowed a position more secure and permanent than the physical sciences. Mechanics holds a place in the hierarchy of the sciences next to pure mathematics, and mechanics consists of measurements and the relations of quantities. Physics, as its measurements are made more complete and exact, becomes mechanics. The late development of the biological sciences was due to the difficulties in the way of applying measurement to the living body. But each step in advance has consisted in overcoming these difficulties. As experiment and measurement are extended to the organism, biology becomes a branch of physics. We may affirm without hesitation that quantity is the beginning and end of material science.
2. Increasing use is made of measurement in daily life.
Clocks, balances, and foot-rules seem indispensable to our present civilization. Thermometers, barometers, lactometers, etc., are no longer looked upon as scientific instruments, and these and other means of measurement will soon be used by everyone. The applications of machinery and the development of the useful arts rest on the increasing use of mechanics and quantitive relations. The history of words used to express magnitudes bears witness to the progress of exact measurement.
