Condition of MicroscojJi/ in England. Eg Frank Crisp. 123 
the ground of the greater practical value of the one over the 
other — is a strange one to be used by scientific men. It is the 
merest truism to say that the only sure way to advance any branch 
of knowledge is by undertaking a complete and exhaustive inves- 
tigation of the theoretical principles on which it is based. All the 
practical inventions ever made have depended for their discovery 
on the previous investigation of mere theories, by men who pursued 
knowledge for its own sake alone, and without stimulus from any 
notions of practical utility. 
As an old writer (Malthus) has put it : — “ It surely would be 
most unwise to restrain inquiry conducted on just principles, even 
where the immediate practical utility of it is not visible. In every 
branch of natural philosophy how many are the inquiries necessary 
for their improvement and completion which, taken sejiarately, do 
not appear to lead to any specifically advantageous purpose ; how 
many useful inventions and how much valuable and improving 
knowledge would have been lost if a rational curiosity and a mere 
love of information had not generally been allowed to be a suffi- 
cient motive for the search after truth.” 
If only the lowest view of the microscope is to be accepted, 
the improvement of the mere tool must necessarily have an im- 
portant influence on the perfection of the work performed by its 
aid, so that the improvement of the microscope will directly further 
the aims of the naturalist. 
Another reason which has also operated to produce the present 
condition of things is, that some kind of belief, more or less 
definite, has grown up, that we have arrived substantially at a 
state of perfection, or at the limits of the possible; that there 
being no further scope for improvement, the study of theoretical 
principles has become a matter entirely of antiquarian research. 
I should not have thought that such a belief could be seriously 
held, had it not received the sanction of one of our high living 
authorities, who, whilst sufficiently cautious to guard himself 
against being supposed to assert the absolute impossibility of 
further improvement, yet, after speaking of the microscope as 
having “ acquired the deserved reputation of being one of the 
most perfect instruments ever devised by art for the investigation 
of nature,” ventures to say that “ the statements of theorists as 
to what may be accomplished are so nearly equalled by what has 
been effected, that little room for improvement can be considered 
to remain until chemists furnish opticians with new varieties of 
glass whose refractive and dispersive powers shall be better suited 
to their requirements.” t 
* ‘ Principles of Political Economy.’ This point has also been vvell treated 
by Professor Tyndall in his concluding lecture on Light. 
t Carpenter, 5th ed., 1875, p. 6. 
