244 ANNUAL REPORT SMITHSONIAN INSTITUTION, 192 8 



was pushed rapidly forward by a number of physicists, and soon gave 

 accurate means of measuring the form of distribution, and spacing 

 of the very molecules of the crystals. It is quite impossible in a 

 short space to give any idea of the tremendous field of activity which 

 these discoveries opened up in relation to atomic structure on the one 

 hand, and the nature of X rays on the other. Not only this, but it 

 soon became realized that there were otlier fields of usefulness for the 

 new method. Not the least among these has been its application to 

 the structure of metals, which has provided the metallurgical engineer 

 with a new method of attack in the detailed examination of his alloys, 

 and of the effect of strain and other treatment upon them. Whereas 

 formerly the limits to the fineness of his examination were deter- 

 mined by what his microscope could see, he is now almost in a posi- 

 tion to look at the very molecules themselves. 



Many years ago. Professor Michelson, of the University of Chicago, 

 became interested in the question of whether or not the velocity of 

 light is affected by the earth's motion. This is an experiment having, 

 at first sight, nothing but a philosophical interest. But Professor 

 Michelson obtained an unexpected re^sult, a result which did not har- 

 monize with our understanding of nature's laws; and herein lay its 

 great value, for it showed that our modes of thought required 

 revision. This great revision, not, of course, in the laws themselves, 

 but in the sense in which we interpret them if they are to harmonize 

 throughout, constitutes the theory of relativity — a way of looking at 

 things which soon made its influence felt out,side of the domain in 

 which it was born — a scheme of thought which has enabled us to see 

 harmony in, and so understand, many wonderful things in the theory 

 of electricity, atomic structure, and other branches of physics. More- 

 over, here again, we meet with a remarkable example of the inter- 

 dependence of the various parts of science on each other. (3f all 

 branches of pure mathematics one could hardly conceive any farther 

 removed from nature than those having to do with noneuclidean 

 geometry, and the ,so-called absolute calculus of Ricci and Levi- 

 Civita. These were fields so specialized as to be studied only to a 

 very limited extent by mathematicians themselves. Yet, even as an 

 archcologist might suddenly come upon a scroll of papyrus outlining 

 the laws of an ancient civilization, and might therein find the means 

 to harmonize, and understand the other visual records which his 

 search had unearthed, ^o Einstein found in these abstruse writings 

 of the mathematicians the wherewithal to express the unity of na- 

 ture's laws in a form so beautiful that he has likened that expression 

 to a wonderful symphony of which our universe is the expression of 

 God's rendering. 



