‘Sournal, Aug 11870. |, CORRESPONDENCE. 115 
it. Tolles marked the grade of that objective too high. It is hardly 
an }th English standard. You put it up to high-water mark in making 
it resolve the 16th band. I was satisfied in getting it well through 
the 15th, and took the 16th partly on trust.” Nevertheless, after this 
lens got back to Mr. Stodder, lines were shown with it which it seems 
a number of my friends in Boston believe were the real ones, though 
none of them appear to have made a count, which, after all, is the 
decisive test. I still believe that my friends were deceived by spu- 
rious lines, and have greatly regretted that I could not drop in on 
them, and look over the shoulder of Mr. Tolles (who is regarded not 
only as the champion maker of objectives, but as the very best mani- 
pulator of his own lenses) to see what it was he really saw. Fortu- 
nately this has recently been done by a disinterested witness. In 
Max Schultze’s ‘ Archiv fiir Mikroskopische Anatomie’ (Band VL., 
S. 205) there has just been published an interesting article by Dr. H. 
Hagen, “Ueber die Mikroskope Hordamerikas.” Dr. Hagen is a 
German gentleman who has recently settled at Cambridge, and whe 
has been appointed a professor in Harvard College. Since he wrote 
the paper above quoted, he has paid a visit to the Army Medical 
Museum, and I have had a long conversation with him about it. I 
found him well instructed in microscopical matters, and must regard 
him as a competent witness. He relates on page 216 how Mr. Tolles 
himself undertook to show him the 19th band with an immersion ,1,th, 
which I understand from him to be the very one in question. He 
showed him lines indeed, but he was unable to count more than forty 
of them. Mr. Tolles himself counted between forty and fifty. These 
counts show that the lines in question were spurious. Dr. Hagen 
concludes, as the result of his examination of the lenses of Tolles, that 
in a general way they are quite as good as lenses of the same power 
by the best European makers, but that they cannot be said to excel all 
others, since as yet none of them have resolved the last four bands. of 
the Nobert’s plate, as the ,),th immersion of Powell and Lealand has 
done.* He naively relates that his unwillingness to admit more was 
not favourably received by the Boston microscopists. “ Ich kann nicht 
unterlassen zuzufiigen, dass schon mein Versuch, ein Urtheil tiber die 
hiesigen Instrumente zu fillen und europdische denselben gleich hoch 
zu stellen, einen Sturm der Indignation unter den hiesigen Mikrosko- 
pikern hervorgerufen hat. Ihre Indignation wird mehr erklarlich, 
wenn man weiss, dass sie fast sammtlich der Boston optical Associa- 
tion angehéren, die bis jetzt ohne Zinsen arbeitet.f 
After this testimony of Dr. Hagen I must be pardoned if I con- 
tinue my disbelief until some evidence more positive than mere 
opinion is offered. 
As to whether I saw the true lines with the ;),th of Powell and 
Lealand, I may simply remark that I supported my statement by a 
count of the lines as well as by the photographs made by Dr. Curtis. 
I thought, and still think, that Dr. Curtis’s photographs were conclu- 
sive evidence that I had seen the true lines, although the spurious 
lines shown on the edges of the band prevented them from serving for 
* See page 217 of his paper. t+ Page 208. 
