Monthy trope and their Merits. 279 
any intimation whatever of Dr. Hagen’s intention of becoming 
“thoroughly acquainted” with the American microscope, for the 
purpose of publication; they were never asked to assist for any 
such purpose. Had Dr. Hagen not spared his “pains;” had he 
inquired tor those who could have “assisted” him in his “study ” 
and have given him “ positive proofs,” he would have been referred 
to Professor Holmes and Professor Bacon of his own university, 
and to Professor Smith, of Hobart College, New York—muecro- 
scopists who have made a study of the microscope for twenty years 
—to Dr. Barnard, President Columbia College, New York; to 
Professor H. J. Clarke, of the Kentucky University; to J. E. 
Gavit, Esq., of New York; to Dr. F. W. Lewis, of Philadelphia ; 
to Professor C. Johnston, of Baltimore; to Mr. J. 8. C. Greene, jun., 
of Boston,—gentlemen who have made the comparison of Kuropean 
microscopes of the best makers, with American instruments almost 
a specialty ; had he done this his study might have produced more 
correct results; that is, if he had given heed to the information he 
received—for he seems to have disregarded that which he obtained 
from Messrs. Greenleaf and Bicknell. 
Dr. Hagen gives his “ general opinion” before giving the details, 
and says “novelty of any importance is not obtained.” Yet before 
he concludes his paper he enumerates six novelties, all vented or 
designed by Tolles; namely, his binocular eye-piece, the illuminator 
of opaque objects with high powers, the low-power immersion lens, 
the solid eye-piece, the mode of effecting adjustment for covering 
glass, and the amplifier, and overlooks others quite important by 
Tolles and Zentmeyer. 
“Objectives and oculars accomplish with slight variations as 
much as the best European, never more; on the contrary, English 
and French objectives have accomplished some things which the 
Americans have hitherto failed to do.” It is not the purpose of 
this paper to produce evidence outside of Dr. Hagen’s own state- 
ments, as to what American objectives have done. It is only need- 
ful to contrast what he says above with what he says he himself 
saw. Dr. Hagen says “that an objective 75th inch with ocular C. 
showed while band 19 [of the Nobert test-plate] was in the centre 
of the field, the 18th, 17th, andvhalf 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 rest blurred.” 
“None of Tolles’ objectives have well resolved the 16th to 19th 
bands of Nobert’s plates, which has been done with the yth of 
Powell and Lealand.” It would seem incredible that the same 
person could have written the above lines in the same paper; most 
especially after he had been positively informed by five gentlemen 
that they had seen the 19th band resolved, and with several of 
Tolles’ objectives. But Dr. Hagen takes the ground (though not 
