_ edition, 1862, he again alters the figures to sidvo, but adds 






96 NOBERT’S TEST PLATE 
Dr. William B. Carpenter, in his work on the Micro ` 
scope, published in 1856, says, “Even the + objective will, 
probably not enable any band to be distinctly resolved, © 
whose lines are closer than yy4so of an inch. At present, 
therefore, the existence of lines finer than this is a matter of 
faith rather than of sight; but there can be no reasonable 
doubt that the lines do exist, and’ the resolution of them 
would evince the extraordinary superiority of any objective _ 
or of any system of illumination which should enable them © 
to be distinguished.” In his second edition issued in 185%, | 
Dr. Carpenter repeated the same remarks, but substituted 
ssboo for zs4ua, and then added, “There is good reason to 
believe that the limit of perfection (in the objective) bas now 
been nearly reached, since everything which seems theoreti- 
cally possible has been actually accomplished.” In the third 
nothing more. m 
On the other side the late Professor J. W. Bailey claimed 
to have seen lines as close together as toovo0 to the inch, 
and Messrs. Harrison and Solitt, of Hull, England, claimed 
to have measured lines on the diatom Amphipleura pellucida, 
as fine as 120,000 to 130,000 to the inch, and expressed the 
opinion that lines as fine as 175,000 might be seen with 
proper means. p 
To determine if possible the truth between these conflict- 
ing opinions, Messrs. Sullivant and Wormley (American 
Journal of Science, January, 1861) made an exhaustive trial 
of one of these “marvels of art.” They state that the opti- 
cal apparatus at their command was ample; it included 4 
“Tolles zy objective of 160° angular aperture, —an objective 
of rare excellence in all respects, —besides 7; and yy obJe® 


PEE = inet ote Re aie a ma eS hr Re O E ecient ne ee ee a 




thirty bands, as previously mentioned. 
“Up to the 26th band (7stov) there was no serious difficulty e 
solving and ascertaining the position of the lines; but on this and #6 
