120 Nobert's Nineteenth Band 



added that not only " objectives of inadequate defining power," but 

 the very best will show spurious lines if they are not properly 

 manipulated. He says, "Now not only did Mr. Stodder in his 

 original paper admit that he had not counted the lines, but he fell 

 into a grave error on the subject of counting fine Imes, which he 

 expresses in the following words : — ' In counting lines of such ex- 

 quisite fineness, either the micrometer or the stage must be moved,' " 

 &c. Had it occurred to me when writing that anyone could have 

 possibly supposed that I referred to anything except such " exqui- 

 sitely fine lines " as I saw them with only 550 diameters, I might 

 have been a little more explicit ; but as I applied the words, they 

 were strictly correct, and I do not retract them. I " fell into " no 

 "grave error" — no error whatever; and of that Dr. Woodward's 

 account of his own experience is sufficient proof. He says, "On 

 attempting to count the lines, however, with a good cobweb micro- 

 meter made by Stackpole, of New York, I found myself unable to 

 get beyond the 9th or 10th hand, on account of the tremor commiL- 

 nicated to the insfrumetit ivhen the micrometer screiv was turned ! I "* 

 This is a full confirmation of my remarks by Dr. Woodward him- 

 self. I can add that Dr. Barnard, of New York, encountered the 

 same difficulty. I will also say, at that time neither Mr. Greenleaf 

 nor myself had any apparatus to assist in counting, and that then 

 I had never even seen a cobweb micrometer. 



Dr. Woodward has been able to find one indorser of his "judg- 

 ment," Dr. H. Hagen, of Cambridge, an eminent entomologist. 

 After an examination of Dr. Hagen, and finding their "judgments " 

 to coincide. Dr. Woodward pronounces him to be "a competent 

 witness." Dr. Hagen has published in Max Schultze's ' Archiv ' 

 (second No,, 1870), a paper " On American Microscopes." In that 

 he relates how Mr. Tolles undertook to show him the 19th band 

 with an immersion To^h. Dr. Woodward renders Dr. Hagen's 

 account in this way : — " He showed him lines, indeed, but he was 

 unable to count more than forty "of them. Mr. Tolles himself 

 counted between forty and fifty of them. These counts show that 

 the lines in question were spurious." Fortunately I have a copy of 

 the ' Archiv.' The correct reading of the passage is (as translated 

 by a German), " An objective of iV^h in focus showed, while band 

 19 was in the centre of the field, the 18th, 17th, and half of the 

 16th bands. The lines in all were well defined, but not so that 

 I could have counted them all. I could count about forty of the 

 19th, the BEST blurred." This is very different from Dr. W.'s read- 

 ing, which is, that the forty counted were the whole width of the 

 band, and consequently spurious. I am authorized to say that 

 Dr. Hagen has stated in conversation that he saw the true lines. 

 In fact, Dr. H. saw the 19th band resolved, though he does not 

 * ' Quart. Joum. Mic. Science,' Oct., 1868, p. 229. 



