192 THE POPULAR SCIENCE MONTHLY 



your consideration: What actual laws of nature have been discovered 

 by the method of least squares? 



The Mechanical Instruments of Eeseaech 

 A few minutes were to have been given to the instruments em- 

 ployed by the scientific man to sharpen and amplify his natural senses 

 and sensations — in a word, the tools furnished him by the mechanician. 

 I am glad, however, both for your sake and mine, that this part of 

 the subject was covered by an interesting paper presented at the pre- 

 vious meeting of the society. It was emphasized there that for the 

 best results it is essential that the investigator be able to work with 

 instruments so constructed as to permit him to control or renew the 

 various adjustments without the necessity of returning the instru- 

 ment to the maker. The principle at times employed, which assumes 

 that when adjustments are once made they are to " remain put," is 

 apt to prove a very pernicious one. A number of very interesting 

 examples from my own experience in the purchase of magnetic instru- 

 ments during the past ten years might be cited; but, as has been 

 said, this part of the subject having already been covered, there 

 is no need to dwell further upon it than to emphasize the injunction 

 that the research worker, if he desires the best results, must know 

 his instruments as thoroughly as himself. 



Subjects of Eeseakch 



We come next to a brief consideration of the subjects of research, 

 though not specifically mentioned in the title of our paper, yet im- 

 plied in it. The rapid progress made by a science as soon as it 

 reaches the stage of experimentation has already been noted. A 

 crucial experiment has at times furnished information which by mere 

 observation of phenomena, running their natural and unmodified 

 course, might either have never come into our possession or at best 

 would have taken a considerably longer time than that of the decisive 

 experiment. You are all familiar with such cases, for almost every 

 science can furnish examples. 



jSTow it is an extremely interesting and suggestive fact that the 

 greatest experimental discoveries to-day are not made in the older, 

 well-recognized sciences, but on their borderlands — in the " twilight 

 zones " of more or less related sciences. I have but to mention the 

 words " physical chemistry," " physical geology," " astrophysics," " bio- 

 chemistry," etc., and you will readily grant the assertion made. In 

 the overlapping regions there seem to be the greatest opportunities 

 afforded for solid, thorough, and at the same time remarkably rapid, 

 experimental achievements. And so we are having produced almost 

 daily new specialties or new sub-specialties. 



