142 UNIFORMITY OF NOMENCLATURE IN OBJECTIVES. 
importance it might be well to give both extremes, or else to: 
ify the angle and power at which the combination was work 
accomplish the results specified. Attention need hardly be call 
to the fact that this great increase of power and angle, amounti 
sometimes to more than one-half of the minimum amount, is d 
entirely, not to the interposition of the cover-glass or other m ed 
but to the change in the relations of the lenses caused by t 
movement of the screw-collar. Where an extra front of diffe 
properties is added, we have essentially another objective wh 
power and angle should doubtless be separately stated. a 
The use of linear measurement in recording and stating po Í 
has become so general that there may now be said to be 
respectable deviation from the custom. In the early histo 
microscopy, powers were generally stated, according to the 7 
flatness or depth of the object, in superficial or cubical me: 
and it was plausibly urged that this represented the real 
enlargement of the natural object; but, aside from the 
venience: of the large and often incomprehensible numbers 
obtained, this method gives in one sense the magnifying 
but in no sense the microscopical power employed. The p 
see small things depends, so far as real or apparent siz : 
cerned, on the distance from each other of minute po 
structure, and this is in the exact ratio of the linear mag 
power. Squaring or cubing this power has acquired a su 
of sensationism, if not of charlatanism, and is generally av 
in science. ce 
If anything could be more confused and confusing 4 
different real and nominal powers of the objectives, it 3 
the corresponding powers of the eye-pieces or ocu ATS. 4, 
without any pretence of uniformity, and named without ant? 
attempt at significance, it has seemed until recently that no © 
from the confusion was to be looked for. Yet it would see 
convenient and altogether unobjectionable to have the o% 
named as to express their magnifying power, and the p 
doing this has been already introduced into this country 
microscopists have re-named their oculars by their m°% 
power, on the basis of one-inch to ten diameters, and Tam 
by Mr. Bicknell that Tolles has already adopted the same 
naming those of his manufacture, discarding the letter 
ture (A, B, C,ete.) and selecting 2 in., 14 in. lins 2 
