SUPPLEMENT. 



371 



so well " to talk about before an audience ") amounts to. Of a 

 piece with this comes his statements that such and such posi- 

 tions of my own are '* not proved," and that before he accepts 

 them he " must know why." 



I submit : that the only possible method of convincing Prof. 

 Hitchcock will be the practical one, in this instance, however, 

 quite impracticable, to-wit : " two (or more) hours conjointly 

 over the tube," or until he shall have done me the honor to 

 adopt my suggestion, and experiment with the high angles for 

 himself ; in the latter case, obviously, he ought not to expect 

 first-class results from the wide angles until at least he shall 

 have learned that something is due to " handling." I repeat 

 that until one or the other expedient is adopted, we might con- 

 tinue the present discussion until doomsday, and on my part 

 without a vistige of any chance of convincing Prof. Hitchcock. 

 I therefore offer the following brief remarks by way of closing 

 a controversy which, in the nature of things cannot lead to any 

 fixed results. 



Prof. Hitchcock asks, " Why strain a one-inch to see 30,000 

 lines to an inch, with a deep eye-piece, when the half-inch 

 would do the same work without being pressed so hard V" 



Well, let us strip things " stark naked," and find out u why." 

 First, with the inch I get better definition ; second, longer 

 working distance ; and, third, because the inch, with deep eye- 

 piecing " is not pressed so hard as the half-inch and this is 

 my reply to Prof. Hitchcock. As a matter of course he will 

 come back at me with the stereotyped assertion, " I must know 

 why." He says, too, u Until his (my) experiments are published 

 and subjected to public examination they are not to be accept- 

 ed, etc." Well, by the laws, my experiments have been both 

 published and subjected to public examination. But, unfortu- 

 nately, Prof. H. wasn't there ! Note that. 



Further, I now propose to put the inch and half-inch to a 

 practical test. Thus, let Prof. Rodgers, of Cambridge, rule a 

 band of 40,000 lines to the inch, and let Prof. Hitchcock count 

 them if he can with a low half-inch (say of 40). I hazard the 

 prediction that he will fail, and furthermore, that I will be 

 enabled to count them with an inch of 45. I am ready for such 

 test in any shape that Prof. Hitchcock may suggest. 



