On the Use of the Noherfs Plate. 33 



I have never, however, expressed a doubt of Mr. Stodder's good 

 aith in his claims, and will not do so now. Still I must call atten- 

 tion to some inadvertencies into which he has fallen. Thus on page 

 120 of his article he passionately denies having made any error as 

 to the matter of counting fine lines, and quotes in proof the passage 

 in his original paper, leaving out the part which contains the error. 

 The whole passage reads, " either the micrometer or the stage must 

 be moved, and it is next to impossible to construct aiipiaraius that 

 can he moved at once the rw^hwoi^^ P'^'^t of an inch and no more." 

 His error, of course, consisted in supposing that if the micrometer 

 is moved, its motions must correspond with the real distance of the 

 lines, instead of the dimensions of the magnified image. The re- 

 marks on tremor which he introduces in this place have nothing 

 to do with the question. 



On the same page he insinuates that I have misrepresented the 

 meaning of Professor Hagen's paper, but here his confessed igno- 

 rance of the language misleads him. I quote a single j^assage in 

 reply. " Bis jetzt keines der objective von Tolles die 16 bis 19 

 Bande in Nobert's Flatten vollig auflost, was mit xVth von Powell 

 und Lealand geluugen."* I might quote several other examples of 

 what I must hope is unintentional untairness, especially his criticism 

 of my photographs, of which I will only say that it contains con- 

 clusive internal evidence that he is unacquainted with the appear- 

 ance of the true lines of the nineteenth band. But I am quite 

 willing to leave this matter in the hands of conscientious students 

 of the plate, and have neither time nor inclination to discuss his 

 errors seriatim. I will close by a brief reply to his demand for 

 my opinion as to Tolles' lenses. 



I have always felt great admiration for the excellent workman- 

 ship of Mr. Tolles. I think his iths and xoths will compare favour- 

 ably with the like powers of the best makers, but I have not found 

 that they excel them, and regard the claim that the ith of Tolles 

 will do the work of the yVth, or his xVths that of the yVths of other 

 makers as utterly unfounded. I have long thought that if Mr. 

 Tolles would apply himself to the construction of an immersion 

 lens of shorter focal length than those he has hitherto made, the 

 result would be gratifying to his warmest friends. Some time prior 

 to the appearance of Mr. Stodder's paper, therefore, I sent through 

 him an order for such an objective. When it reaches me I will 

 endeavour to do it full justice ; in the meantime I reply directly 

 to Mr. Stodder's question, that I have two |ths by Powell and 

 Lealand now in the Museum, each capable of resolving the six- 

 teenth band of the plate, which is all I have ever been able to do 

 with Tolles' rVth or x^th. With this I take leave of the subject. 

 * Max Schultze's ' Archiv,' Bel. vi., p. 217. 



