22 IOWA ACADEMY OP SCIENCES. 



PRESIDENTIAL ADDRESS. 



SOME FEATURES OF THE SCIENCE OF A HUNDRED YEARS AGO. 



BY W. S. HENDRIXSON. 



In the past three or four years the popular magazines have 

 contained numerous articles on the progress of science in the 

 nineteenth century. These papers were written for popular 

 information and they deal with only a few great discoveries 

 with which all men of science are familiar. It occurred to the 

 writer that for the entertainment and information of the 

 man of sciecce, who is acquainted with the main facts and 

 theories of every science as it is to-day, and who, though not 

 acquainted with its minute details, is at least aware of its great 

 mass of facts, its intricate theory, and ponderous and ever 

 increasing literature, it would be more to the point to define the 

 conditions of science as it was at the beginning of the century, 

 and let him arrive at a conception of its progress by subtrac- 

 tion. 



Upon actual trial I found the process fascinating in more 

 ways than one, and it occurred to me that it might be interest- 

 ing to us to-day to look back 100 years, or abaut the extreme 

 limit of a human life, pay our respects to some of the worthies 

 of that day, take a view of their science and contrast it with 

 our own. 



It seems wise to restrict our attention to the universally 

 recognized natural sciences, and indeed to those that furnish 

 topics for discussion in this body: Chemistry, physics, biology 

 and geology. 



It will be necessary, and we hope interesting, to trace each 

 of these sciences from its birth, so nearly as that date can be 

 determined, down to the even date 1800, or 100 years ago, giving 

 dates of important discoveries both in fact and theory. There 

 must always be uncertainty regarding the dates of many dis- 

 coveries. To cite examples, we may trace an atomic theory and a 



