On the Aperture of Object Glasses. 103 
4 Art. XIUI.—On the Aperture of Object Glasses; by F. H. 
Wenuay, republished* from the London Quarter! y Journal of 
Microscopic Science for October, 1855. 
r 
in balsam, I beg to state, that my observations were dictated by 
ho other motive than the desire of establishing a correct fact, 
| and that I was not prejudiced by any favorite theory. 
N er Bailey says, ‘It is apparent from the above that Mr. 
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quite agreed; but as Prof. Bailey’s allusions extend beyond this 
point, self-defence will be my apology for taking some notice of - 
them. Referring to me, Prof. Bailey says, ‘the error in his ar- 
guments will be sufficiently obvious to any one who will trace 
the course of divergent pencil out of the balsam instead of into 
it, asin Mr. Wenham’s experiments, and it will then be seen 
that large angles of aperture are as useful for balsam-monnted 
_ Specimens as for others.’ Surely Prof. Bailey cannot have well 
Onsidered this extraordinary, because extremely incorrect, asser- 
ton, which is tantamount to saying, that a divergent pencil of 
Tays from a Inminous point, submerged in balsam will in each 
Case continue their course in the same straight line without suf- 
By request of Prof. Bailey. 
oe 
