The Theory of Immersion. 225 



So then this is what we have come to. We are to set aside a 

 scientific principle because Dr. Woodward is sure that Mr. Tolles is 

 sure that he could get over it. To make any commentary on this 

 would be to spoil it. Indeed a practical comment of a very amusing 

 kind was by mere accident supplied immediately. Mr. Tolles had con- 

 structed an object-glass which he labelled with the astounding angle 

 of 180°. And not only constructed it, but in an evil hour sold it to 

 an English gentleman, Mr, Crisp, httle thinking that in so doing he 

 was selling himself into the hands of the Philistines to be shorn 

 and made sport of. Mr. Crisp lent it to Mr. Wenham, who of course 

 proceeded to test it. We know what came out. The light had got 

 in at the wrong side, and when it was cut off the true angle came 

 out some 70° less than the label. How it could be that the ab- 

 surdity of supposing such an angle to be even conceivable did not 

 awaken the suspicions of the maker is what will probably never be 

 known. I say conceivable, because such an angle necessitates the 

 proportion between the breadth of the front and the focal distance 

 to be not only great but absolutely infinite. I think I am well 

 within the truth in saying that this if not the greatest is certainly 

 the most ludicrous error ever published by any optician living or 

 dead. And this is the artist on faith of whose learning we are asked 

 to set aside a law of optics. 



I am very well aware that to everything here said, or that can 

 be said by me. Dr. Woodward has a short and easy answer. It is 

 all disposed of in two words — " total ignorance ! " It is not even 

 an argument at all ; it is only an " effusion." This, no doubt, is 

 one way of answering. Of course, if Dr. Woodward thinks it seemly 

 and consistent with self-respect to come down to this kind of thing, 

 that is chiefly his own affair. But does he think anyone is deceived 

 by it ? or that everyone does not see in it the sign, not of one who 

 has gained his cause, but of one who has lost his temper ? 



It is therefore, I think, now apparent that this controversy has 

 worked itself to a natural end. It may be, perhaps will be, con- 

 tinued by some one still ; but it can only be in a verbal or personal 

 way, not to any scientific end. Where everything vanishes as soon 

 as you touch it, to pursue a question farther is only to pursue a 

 shadow ; and it is quite useless to go on with a controversy where 

 there is nothing left to controvert. 



I proceed therefore now to the theory itself. 



{To he continued.) 



s 2 



