RELATIONS OF THE AIR TO OUR CLOTHING. 655 



Therefore it will be maintained by many that such lectures produce 

 more evil than good, creating as they do, and augmenting, that dilet- 

 tanteism from which our period is already suffering. In our schools 

 also this dilettanteism is gaining such dimensions, that one might get 

 thoroughly frightened at the immoderate expansion of young people's 

 knowledge, were it not for its small depth, which lessens the danger, 

 and for the fact that the forgetting keeps pace with the learning. 

 Accept my open avowal, that I also am unable to invalidate the ob- 

 jection that popular lectures on scientific subjects are not able to im- 

 part a really competent knowledge, and do not form experts. 



But I believe that this does not matter, and that they have no 

 such purpose. They are neither an exhaustive, scientific, nor a prac- 

 tical instruction, but a scientific edification and elevation, which are 

 to raise our minds and hearts, and to affect us like listening to good 

 music to a symphony, the purpose of which is certainly not to make 

 musicians of all the listeners. It is sufficient to feel the harmony 

 which lies in the nature of good music. There is harmony in all our 

 knowing and doing, our aiming and striving, as far as there is truth 

 in them, and fortunately the sense for perceiving this harmony is as 

 widely spread among mankind as the sense for music. This harmony, 

 which pervades every truth, ought to be brought home to the con- 

 sciousness and feelings of everybody, so that the greatest number 

 may rejoice and become interested in it, that we may approach new 

 subjects, and perhaps make them our study, or that, at all events, 

 knowledge and resulting sympathy may induce us to lend our help to 

 those men whose profession and calling require them to enter more 

 minutely and exactly into the subjects in question. In this respect 

 popular lectures have a high and serious mission. It is their mission 

 to create correct general ideas, to facilitate our grasp of them, to 

 awaken and spread a certain love for different tasks of mankind and 

 ol the period, to form ties of friendship between things, ideas, and 

 men. Sympathy and sacrifices cannot be expected or asked from us, 

 if their objects are unknown to or badly understood by us. 



For these reasons it is my desire to awaken your interest for some 

 subjects relating to hygiene, and particularly to impress upon you 

 most vividly how much in this respect remains to be done and created, 

 a work we all ought to take our share in. 



One of the incessant wants of man is air. 



We want air mainly to nourish us and to keep us cool. The quan- 

 tity of air inhaled and exhaled by an adult in twenty-four hours 

 amounts on an average to about 360 cubic feet, or 2,000 gallons. 

 What we take in and give out during twenty-four hours, in the shape 

 of solid and liquid food, occupies on an average the space of 5^ pints, 

 which is equal to -30V0 f the volume of the air passing through our 

 lungs. It will astonish you to hear, perhaps, for the first time that 

 this amounts to 730,000 gallons in one year, and to be reminded of 



