258 COERESPONDENCE. [^jCmli^ioT^T^m' 



made by Tollcs, as described in my paper, before referred to. We 

 were both familiar with the appearance of the lines (and of the " spec- 

 tral " lines), having worked on them a great deal, and being conver- 

 sant with all that had been published by others. Unfortunately that 

 objective was broken before other experts had seen its performance. 

 Mr. Tolles subsequently, in the winter and sjiring of 1868, made other 

 immersion objectives, and put immersion " fronts " to " dry " objectives 

 of his own and of A. Eoss's make. One, a ^th, was made in June, 1868, 

 for Herr Th. Eulenstein, of Dresden. This, I think, resolved the lines 

 in Mr. Tolles' hands ; but of this instrument more anon. x\nother 

 one, originally a ith of Tolles' make, had an immersion front in July, 

 1868. This showed the lines of the 19th band immistakably, clear 

 and well defined. The performance was seen by the owner, by Mr. 

 E. Micknell of Salem, by myself, and jierhaps some others. This was 

 nine months before the Powell and Lealand sixteenth was made. 

 After this other objectives were made by Tolles, which did the same 

 thing. 



In the spring of 1869, Dr. W. received his Powell and Lealand 

 y\rth, and then for the first time he resolved the lines of the 19th band. 

 I will not doubt but he sato the lines ; but the photographs do not 

 show them as I have seen them. In May, 1869, I sent to Dr. Wood- 

 ward the y y th immersion objective, which he refers to in his paper in 

 the ' American Journal of Science ' of September, 1869, and in the 

 communication to this Journal, in December, 1869, which objective he 

 calls a ith, and in a letter to me states that it is only about one-lialf the 

 power * of the Powell and Lealand y\jth. With this he saw the lines 

 of the 16th band; a feat that had not then been certainly accom- 

 plished in Europe with any instrument that I have any accoimt of. 



This objective was returned to me, and was put into the Exhi- 

 bition of Massachusetts Charitable Mechanic Association in Septem- 

 ber. A comj)etent board of experts were selected to examine instru- 

 ments. In their presence, and in the presence of Dr. B. A. Gould and 

 Professor W. Gibbs, of Harvard College, the lines of the 19th band 

 were clearly and plainly resolved with that same objective. Two of 

 the gentlemen who witnessed this had also seen Dr. W.'s resolution 

 with the Powell and Lealand, and had no comj^unctions in saying that 

 the ^\ih did as well, if not better, than the ^'^jth, with all the elaborate 

 aids used at the United States Army Museum. 



Let me hope that this detail of facts in chronological order, will 

 settle all questions of priority, both of observers and makers. If Mr. 

 Lobb has any doubts remaining, if he will just step over to this side 

 of the Atlantic, I shall be happy to show him the lines finer than the 

 16th band " clearly defined " with a ^Lth. 



I have referred to a ^th made for Herr Eulenstein in June, 1868. 

 He has expressed gixat approbation of this instrument whenever he 

 has referred to it; but in the last month, February 11th, he writes to 

 me from Dresden as follows : " I have sent the ^th to Nobert. We 



* It has feince been measured by two experts independent of each other and 

 of the maker ; one made it a large -Jtli, the otlier a J^th, consequently the Powell 

 and Lealand is either a Jgth or J^tli. 



