62 POPULAR SCIENCE MONTHLY. 



the technical side, because of the patience and manipulative skill re- 

 quired, and difficult on the intellectual side because the comprehension of 

 many measuring instruments is dependent upon advanced theory and 

 considerable analytical power, it has not been forgotten that the labora- 

 tory may serve certain other though perhaps minor purposes. Just, for 

 instance, as aid to distinct thinking maybe rendered by the use of mathe- 

 matical symbols and models, so also it will probably assist the unimagina- 

 tive student to comprehend the laws under discussion if he can examine 

 under his own manipulation the behavior of the apparatus which em- 

 bodies those laws. Again there are certain phenomena which should 

 be given the student for personal examination in the laboratory. 

 Thermal phenomena involving the reading of thermometers; the pas- 

 sage of a liquid through the critical state ; the study of compound tones ; 

 the observation of spectra, diffraction and polarization of light waves 

 are examples of the kind of phenomena which require laboratory in- 

 struction. The number, however, of such exercises which appear even 

 in the manuals of a college course is insignificant. 



The pedagogists who, either with or without any definite knowledge 

 of exact science, are perfectly sure how it ought to be taught assert 

 that the first step in all good teaching is an appeal to the observing 

 powers. "It is a cardinal principle in modern pedagogy that real and 

 adequate knowledge of things can be obtained only in the presence of 

 the things themselves," says one. Assuming that this is as true as the 

 author thought it to be, it is but a half truth, the other half being that 

 the presence merely of the things can not impart any really adequate 

 knowledge. A boy, for instance, might watch the motion of the planets 

 till he was gray without ever learning the first thing about gravitation 

 or the solar system. Facts are but the raw materials of knowledge upon 

 which the reasoning faculties must be exerted in order to extract 

 the hidden principles of nature. 



A writer of a well-known series of text-books has adopted as a sort 

 of motto for his pupils, 'Eead nature in the language of experiment/' 

 One can not crtiticize an oracular utterance of this sort for the reason 

 that it is not possible to say just what its author had in mind. If it is 

 meant that empirical knowledge derived from the observation of de- 

 tached facts and not brought into accordance with other facts by means 

 of a hypothesis concerning their relation is sufficient for one to divine 

 the laws of nature, we must certainly dissent. The language of ex- 

 periment is in general a most difficult one to read, since, as we have 

 been insisting, the measurements are in the great majority of cases 

 indirect and to be interpreted only by tracing through a train of com- 

 plex relations the consequences of the things observed upon some hypoth- 

 esis whose truth it is desired to test. 



