54 THE REALITIES OF MODERN SCIENCE 



experiment and close scrutiny of the data obtained, so 

 that new or unexpected phenomena may be detected. 

 To-day it is possible, as a rule, to obtain from in- 

 strument makers apparatus with which very precise 

 measurements may be made. The average experi- 

 menter does not have much difficulty in satisfying 

 the second qualification. With the aid of accurate 

 instruments and machines much of the experimental 

 work of the commercial world of industry may be 

 performed by assistants who lack the other two quali- 

 fications. The experiments are, however, planned and 

 scrutinized by scientists who satisfy more fully these 

 other conditions. In fact, without a large measure of 

 ability of this character, the experimenter becomes but 

 a human part of the machine which he operates. An 

 experimenter who lacks the first and third qualifica- 

 tions bears to a true scientist the same relation as the 

 driver of a locomotive which is guided by the rails and 

 switches bears to those navigators like Columbus who 

 sailed across uncharted seas. 



Of the true scientist the seventeenth century furnishes 

 many good examples. Of Gilbert and Galileo we have 

 already learned. Of Torricelli (1608-1647), Pascal 

 (1623-1662), Boyle (1627-1691), Hooke (1635-1703), 

 and Newton (1642-1727) it is desirable to learn more, 

 since various principles or laws of physics are known 

 by the names of these discoverers. For example, 

 the statement that stress is proportional to strain, is 

 Hooke's Law. 



Torricelli was a disciple of Galileo who devised the 

 barometer. Now, the ancients had used pumps for 

 lifting water, and had observed that in the pipe of a 



