12 



THE PEESIDENT'S INATJGTJEAL ADDRESS. 



and Joy, tlins appealed to, said : " Oli, any ono can see wln'ch. 

 way it falls ! " pointing it out. TIio marble was then handed 

 to Joy, Harrison saying at the same time : " Tin's will prove 

 the fact withont fail. Will my learned friend be kind 

 enough to place this marble on the centra of the model, and 

 not at cither end, to show which way it does fall ? " 



Joy did so with full confidence; but to the surprise of all, 

 Committee included, it again ran the wrong way. The 

 astonishment was so great, and the deception of the eye so 

 complete, that the members of the Committee tried it them- 

 selves over and over again, wondering at the marble always 

 running, apparently, up hill. They thus found out that 

 thoy could not, in all cases, believe the evidence of their 

 own eyes. 



Those eye deooptions, as most of you doubtless are aware, 

 are not very uncommon. For example : a Grecian column 

 has to be bulged in the middle to make it looh straight. If 

 a straight horizont.al tie rod. in an iron roof is, from the 

 position of the observer, cros.scd by two other rods at a 

 wide angle with it, like a broad letter A, the tie rod will 

 appear to be greatly bent at the points of crossing ; and the 

 eye cannot reconcile itself to this deception so as to make it 

 look straight when you know it is so. I could adduce more 

 in.stances ; but these may suffice as an illustration of the 

 fact. 



And now. Gentlemen, I think I have occupied your time 

 long enough in this disoursory fashion ; and I will, with 

 much pleasure, make way for Mr. Morgans and liis more 

 pertinent discourse upon the subject of Chilled Iron. 



