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Transactions of the 
objectives should be named by their performance uncovered mea- 
sured by lamplight at ten inches, and -who attach an extreme im- 
portance to these conditions, which I confess I do not appreciate. 
Nor do I attach any blame to the distinguished manufacturer by 
whom this objective was constructed for the trifling deviation from 
his intended standard ; and I may add that having published the 
above facts, I consider my duty in the matter discharged, and 
whether others choose on the above data to call the objective T Vth 
or -rgth, I shall continue to do as I have done in similar cases, 
namely, pending the adoption of a rational system of nomenclature, 
I shall continue to designate it by the name given by its maker, 
and having published its actual magnifying power under definite 
conditions, shall confine myself to a description of the work it 
will do. 
With regard to the performance of the dry combinations of 
this objective, I will merely say that they gave me the striae of 
Amphipleura pellucida rather better than any dry objective I have 
ever tried. I have not tested them as yet to any extent on other 
objects, because of the manifest superiority of the immersion work. 
The behaviour of the objective, when used wet, is certainly 
admirable. In illustration I forward a new series of views of 
Nobert’s plate from the lowest to the highest bands taken by it. 
These pictures, which certainly excel all my former work on the 
plate, were purposely taken from the ordinary thick-bottomed plate, 
accessible to most microscopists, in order that those interested 
might compare what they can see by their objectives with the work 
now submitted. Most of the negatives were made with a power of 
about 1200 diameters; but as paper prints of the 19th band, with 
this power, are so indistinct as to be practically valueless, I have 
added one of the 19th band from a negative taken with about 1800 
diameters, one of the 15th, for comparison, taken at the same dis- 
tance, with the same cover correction ; and lastly, an enlargement 
of the 19 th band picture, which I hope will serve to illustrate the 
subject of spurious lines on the edges of the band, as well as to 
display the fine resolution of the real lines obtained by the objective 
employed. 
It will of course be expected that I should say something of the 
comparative merits of this new objective of Mr. Tolies, and the 
immersion front of the Powell and Lealand x Vth, which has done 
so much good work for me since 1869. 
Certainly I must give the new Tolles’s objective the preference 
on the plate, and on Ampliipleura pellucida, both by sun and 
lamplight. On other tests I have not as yet done enough work to 
particularize. As to magnifying power, it will be remembered I 
have already published the fact that the wet front of the Powell 
and Lealand’s Ath, belonging to the Museum, magnifies at its 
