September 8, 1911] 



SCIENCE 



313 



found in any treatise on phj^sics. Taking the 

 one which happens to be nearest my hand, that 

 of Magie, I find the subject treated completely 

 in four pages. The point I wish to make is 

 that these matters are taught in freshman 

 courses. But who takes these courses? 

 There is the rub. Of course we know that 

 all engineering students are compelled to take 

 courses in physics. We also know that most 

 chemists take them. Some now even take 

 courses in mathematics, and when a chemist 

 gets a control of mathematics, we know how 

 he makes mathematics hum! One would ex- 

 pect that every medical student would be re- 

 quired to take a course in physics. In other 

 countries this is so. I remember how the ele- 

 mentary courses of Helmholtz and Kundt 

 were so choked up with " Mediziner " as to 

 cause them to grumble. But I fancy that in 

 this country things are here as elsewhere, 

 somewhat at loose ends. A few years ago I 

 remember hearing an address by Dr. Welch on 

 the relations of medicine to physics, so clear, 

 so luminous, so interesting, so learned that it 

 seemed to me that no other medical man in 

 the country could have given it, and I thought, 

 fortunate is the medical school that has such a 

 teacher! But why should not everybody de- 

 siring to be liberally educated study physics? 

 T do not stop to give the reasons, everybody 

 that is liberally educated knows them. And 

 yet we see chemists, psychologists, physiolo- 

 gists, microscopists and many others, every 

 one of whose tools is physical, ignorant of this 

 fundamental science and its methods, and the 

 intelligent man in the street is asking whether 

 the drought is due to the great increase of 

 electric railroads ! And how many of our 

 colleges require everybody to take a course in 

 physics? I can not answer this deiinitely, 

 but I know of only one, Princeton, and I will 

 say to the honor of that institution that I was 

 told that this was the only subject on which 

 the faculty was unanimous. 



But Dr. Gulick's letter is on a very impor- 

 tant subject, on which an enormous amount 

 depends, and on which little seems to be 

 known. The question is, briefly, what is the 

 advantage of out-doors over in-doors? All I 



can contribute to this is a little scientific 

 common-sense. If it is due to the air,, as 

 seems implied by most writers, what proper- 

 ties has the air? These can be of only three 

 kinds: first, physical; second, chemical; third, 

 biological. The physical properties are very 

 simple and easily investigated. They are its 

 temperature, pressure and density, and the 

 density of water vapor in it. To these I ven- 

 ture to add its ionization. No discussion is 

 now complete without some mention of ions, 

 so put that in. Do not forget the sunlight. 

 The chemical aspect is simple and consists 

 only in the' knowledge of the amounts of the 

 various gases present. Finally, there is the 

 question of what and how many microorgan- 

 isms are present. This, the most difficult and 

 perhaps the most important of all, we may 

 turn over to the biologist. Dr. Gulick, who 

 says that he has digested all the literature 

 found in the bibliographies, says that " we 

 know definitely" that there is -no such thing 

 as a subtle human poison (anthropotoxin) 

 which varies in proportion to the C0„. Very 

 well, but, to use the vernacular, " they tell me 

 different." 



As an illustration of what I have said, con- 

 sider what happens when a man smoking a 

 cigar comes into my neighborhood. The first 

 impression that I get is a sense of filth (stink 

 is what the Bible says). This is psycholog- 

 ical, and I will not go into it. Then I real- 

 ize that the chemical equilibrium of the at- 

 mosphere has been destroyed, and that a for- 

 eign physical body has been introduced, 

 though whether the pressure of the air has 

 been altered I can not say. Also whether 

 there is an anthropotoxin present I can only 

 query, although I know one anthropos that is 

 immediately toxized. 



ISTow for the question, what is out-doors? 

 Obviously the question of doors and walls is 

 not the main thing. We know that, ceteris 

 pariius, the same effects will follow. The 

 only question is as to what " ceteris " are 

 " paribus." Does any one doubt that, if the 

 air is physically, chemically and biologically 

 (microorganisms) the same indoors and out, 

 the physiological effects will be the same? 



