160 THE AMERICAN MONTHLY (Jun 
The laboratory worker wants as much done for him as 
possible, so that it may only be necessary for him to place 
his object on the stage and “spot” the structure. To get 
the best from lenses and condenser is not in his province. 
‘Numerical aperture,” “aplanatic cone,” and “‘critical im- 
age’’ are, as a rule, vague terms to him. Hence it comes 
that an instrument that always has its substage conden- 
ser approximately focussed and centred, and the mirror 
fixed in the line of the optical axis, saves him time and 
bother and suits his methods of working. 
No one can defend the use of what are in reality but 
rough and ready means of examination of structure, and 
no reliance can be placed on deductions made from such 
methods. We are among those who are sanguine enough 
tohope that in the no very distant future, the advantage 
of perfect control in manipulation,and a rigid tripod foot, 
as provided in the majority of British microscopes, will 
supersede the Continental model. 
This can only be brought about by a demand for more 
thorough teaching of microscopical principles and manip- 
ulation, and if good work is to be done in English labo- 
ratories it should be seen to that those who use the in- 
struments shall get the best possible out of them. If this 
necessity were recognized and taken up vigorously by the 
scientific world—and many know full well how much it is 
needed—a different state of things would in time prevail. 
We would not advocate the pandering to a low degree of 
appreciation by reducing either the calibre or working ac- 
curacies of the instrument. Let us all do our best to raise 
the users to a higher level. 
Meanwhile, the British manufacturer has opportunities 
of making his instruments more acceptable in several 
ways, and especially in the casing and general “fit up.” 
A great improvement has taken place in recent years, 
but there is yet room for further effort. Generally speak- 
ng, British houses are inferior to their Continental rivals 
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