NATIONAL HEALTH AND WORK. 653 



has been said, it is clear how seriously the small fraction of an inch of 

 expansion could affect it. It is an application of the old law of the 

 elbow-joint press reversed, the working pressure taking the place of 

 the resistance. The work is done at a great disadvantage, but the 

 power is almost limitless. 



A very good instance of " sun-kink " could be seen some years ago 

 on the wooden bridge leading from the elevated railroad station at 

 One Hundred and Fifty-fifth Street, in this city, toward Ninth Ave- 

 nue. A gas-pipe of wrought-iron was laid on the floor of the structure. 

 As if to render it more susceptible to the rays of the sun, it was painted 

 of dark color. On cold or cloudy days it lay in its normal position. 

 On sunny days, the writer has frequently seen it bowed outward nearly 

 or quite a foot out of line. The surface of the foot-planks under this 

 part of it became worn by the daily friction. Finally, an arrange- 

 ment of bends was introduced that operated as an expansion- joint, 

 and now no bowing takes place. 



Even 50° Fahr. seems a large rise in temperature. But it must be 

 remembered that the temperature of rails, or similar objects, is affected 

 by the radiant heat of the sun as well as by the atmospheric tempera- 

 ture. The latter is only the initial factor. The sun's rays could easily 

 raise their absolute temperature above 100° Fahr. 



NATIGIS'AL HEALTH AND WOEK.* 



IT was very difficult to select, from the vast number of subjects relat- 

 ing to health and to education, one of which I could fitly speak to- 

 day. On general education I could not venture to speak ; and, believing 

 that I should have to address a large and various audience, I thought 

 it would be best to choose a subject by which I might urge one of the 

 chief objects of this Exhibition, and one which I know that you, sir, 

 have always had in view, namely, that the public themselves should 

 consider, much more than they do, the utility and the means of main- 

 taining their own health. I have, therefore, chosen the relation between 

 the national health and work ; especially as it may be shown in a few 

 of the many examples of the quantity of work which is lost to the 

 nation, either through sickness or through deaths occurring before the 

 close of what may fairly be reckoned as the working-time of life. I 

 think it may be made clear that this loss is so great, that the consider- 

 ation of it should add largely to the motives by which all people may 

 be urged to the remedy of whatever unwholesome conditions they may 

 live in. It is a subject which is often in the minds of the real students 

 * Address delivered at the International Health Exhibition, London, Juno 17, 1884. 



