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Miscellaneous Intelligence. QT © 
explains the apparent anomalies which occur at St. Helena and Singa- 
pore on the hypothesis induced from the whole of the phenomena. 
scopes from Mr. Ross of England, Mr. Spencer of America, and M. 
examination, particularly as it was made under peculiar circumstances 5 
namely, by adapting alternately the objectives to the same mounting, 
ten times; Ross’s was the feeblest, that of Spencer the strongest. 
The angular opening was first measured with great accuracy and 
found as follows :-— ; 
Ross, ; ‘ ; ‘ ; . . 16 
Spencer, , ‘ . ‘ ; : 135° 
»  Nachez, . + . ° ; P 7 10 
These measurements were all verified by the respective owners of 
these lenses. 
_ The objects examined were the most difficult test-objects among the 
siliceous infusoria, as the Navicula angulata, one of the species of 
Gramatophora, and a Navicula called the Amici test. The first two 
were in balsam. 
The lenses were first attached to one of Nachez’s mounting, and the 
best adjustment of oblique light used that this instrument affords. The 
difference in the effect of the three lenses was very slight, all failing 
to show the lines on the Gramatophora or on the Amici test. AAs not- 
Thus arranged, the lines on the Gramatophora were distinctly and 
tifully seen by all, with slight advantages in favor of Spencer and Ross, 
the former of which magnified them most. ; 
_ The Amici test was next tried which resulted in Ross showing the 
lines with perfect satisfaction; Spencer showing them, but not quite 
80 well; Nachez still less distinctly. 
I would remark that this difference between the lenses appears to be 
Owing entirely to difference in the angle of opening, for where a very 
‘Oblique light is necessary to show lines, the lenses must be so con- 
b 
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_ ‘Structed as to admit this light. I would also state that Nachez’s system 
