THE PHYSICAL LABORATORY 109 



whole experiment water is being lost by evaporation. When we con- 

 sider all these corrections that must be carefully made as well as the 

 fact that to accurately read the height of the mercury in the thermom- 

 eter it would probably be necessary to look at it with a telescope, the 

 difficulties in this simple experiment and the temptation to slight some- 

 thing are very apparent, and yet this is what we expect a freshman to 

 do in the time of about two hours in the laboratory, and at the same 

 time we expect his result to have an accuracy considerably better than 

 one part in a hundred. 



The second and in many cases far more important function of the 

 laboratory is to serve as a place for the performance of accurate re- 

 search, that is, the investigation and discovery of new phenomena. In 

 order to take part in this inspiring occupation it is obvious that the 

 student must have acquired a considerable amount of proficiency and 

 have already made measurements of a great variety involving a high 

 degree of precision. It is often supposed that scientific discoveries are 

 attended with a large amount of luck, or that they are the result of a 

 sudden inspiration whieh may come to anybody. Such is far from being 

 the case. Professors of physics are frequently the recipients of visits 

 from persons who in their enthusiasm feel that they have made an im- 

 portant discovery, which in many cases has been thrown off as a sort of 

 by-product in some other vocation. Not many years ago I received a 

 visit from a young man who had traveled over two hundred miles to 

 present to me the results of a theory which he had elaborated to account 

 for the motion of rotation of the planets on their axes. After I had 

 inquired whether he had made himself familiar with the writings of the 

 great masters in celestial mechanics, and had explained to him the 

 impossibility of his theory, I asked him this question, " Do you realize, 

 my dear sir, that if your theory were correct, it would upset the conse- 

 quences of all the astronomical observations that have been made during 

 the last two hundred years ? " The young man went away sadder but 

 wiser and I did not hear from him again. As a matter of fact discov- 

 eries are seldom made by persons not possessing the training that I have 

 described, and in ninety-nine cases out of a hundred the element of 

 chance is reduced to the smallest possible dimensions. 



I have already stated that the provision of great physical laboratories 

 in connection with instruction is extremely modern. In England the 

 pioneer work in systematized instruction was done in Oxford and Lon- 

 don about 1867. The Clarendon Laboratory at Oxford was built from 

 1868 to 1872, while the Cavendish Laboratory in Cambridge was, as has 

 been stated, not opened until 1874. In this country the first systematic 

 laboratory course in physics was organized about 1870 by Professor 

 E. C. Pickering, at the Massachusetts Institute of Technology, which 

 illustrates one of my points that I have already made, for Professor 



