AND MODERN MICROSCOPES. 97 
subsequent ones, spectral lines, that is, lines composed of two or more 
real lines, more or less prevailed, showing that the resolving power of 
the objective was approaching its limit. By a suitable penta ad 
however, of the illumination, these spurious lines were separated into the 
ultimate ones on the whole of the 26th, and very nearly on the whole of 
the 27th band (şīżr7); but on the 28th, and still more on the 29th, they 
lines of the 30th band we were unable to see, at least with any degree of 
certainty.” 
‘ These experiments induce us to believe that the limit of the resolva- 
bility of lines, in the present state of the objective, is wellnigh estab- 
lished,” and they draw the conclusion, “that lines on the Nobert’s test 
plate, closer together than about yg¢oy of an inch, cannot be separated 
by the modern objective.’ 
Although the paper of Messrs. Sullivant and Wormley 
was republished in the Quarterly Journal of Microscopical 
Science, in London, and might be considered as being a 
challenge to the opticians and microscopists of Europe to 
show what they could do in resolving the test plate, yet no 
report can be found of any attempts to resolve the lines 
until 1865, when Max Schultz (Quarterly Journal of Micro- 
scopical Society, January, 1866) described the Nobert plate 
of nineteen bands, and gave the results of his trials for resolv- 
ing them. “The highest set he has been able to define with 
central illumination is the 9th, which is resolved with Hart- 
nack’s immersion No. 10, and Merz’s immersion system zy. 
With oblique illumination he has not been able with any 
combination to get beyond the 15th.” It will be seen by 
reference to the table that Schultz saw finer lines than Sulli- 
vant and Wormley. ‘This is the only report we can find in 
print from Europe. 
In this country we find no published results; but Mr. R. 
C. Greenleaf, of Boston, and the writer were well sati 
that they saw the lines 90,000 to the inch with a Tolles’ 3 
in 1863, and the next year Mr. Greenleaf saw the same 
lines, unmistakably, with a Tolle? 3+. Dr. J. J. Wood- 
ward, of Washington, in a communication to the Quarterly 
Journal of Microscopical Science, London, October, 1867, p. 
13 
AMER. NATURALIST, VOL. II. 
