7 
speaks of an Iliad of Homer written upon parchment which was 
contained in a nutshell, and must have been written by the aid of 
a magnifying glass; and Seneca refers to writings which appear 
“ larger and clearer when viewed through a globule of glass filled 
with water: we may therefore, I think, fairly conclude that 
lenses, as such, were of a very early date. 
But we must bridge over some centuries and come to the 
year 1585 before we can ascertain that a series of lenses were in 
various ways united together in one instrument, thus forming the 
germ of the compound achromatic microscope. About this 
period Jensen and Drebull, working quite independently, pro- 
duced microscopes which, crude as they were, must be pronounced 
to be of a compound type ; and in the year 1668 the account of a 
microscope manufactured by an optician named Divini, was read 
before the Royal Society. In 1738, Lieberkuhn’s invention of 
the solar microscope was communicated to the public and 
produced a startling sensation, and enormously increased the 
number of workers in this field of scientific investigation. Inthe 
year 1818 experiments were carried out with the endeavour to 
render the combination of lenses achromatic, although at that 
time we read “ that opticians regarded as impossible that this 
end could be attained ;” but in 1829 Mr. Lister succeeded in 
rendering his objectives almost achromatic, by joining together 
a plano-concave and a convex lens by means of Canada balsam. 
Since this date the progress of the microscope has been rapid. 
Year by year fresh improvements have been noted, both in perfec- 
tion of lens, definition, and in mechanical arrangement, until now, 
with the introduction of the Jena glass. for use in objectives, it 
_ almost appears as if the limit of human inventiveness has been 
compassed. But still so insatiable is the microscopist for some 
fresh advance in his beloved science, that, like Oliver Twist in 
Dickens’ famous novel, we are constantly asking for more. 
But now let us consider in what manner the microscope has 
been of such enormous importance in the progress and develop- 
ment of some of the sciences. Let us in the first place take 
the science and art of medicine and surgery,” as diplomas 
have it, together with their subsidiary adjuncts of physiology, 
biology, and pathology, which from vague imaginings, drifting 
hither and thither without any solid basis or foundation, have 
_ grown into well-defined sciences dealing with hard and solid facts 
under the fostering care of the parent medicine. It is true that 
in early days, when the compound microscope first came into 
existence, medical men looked askance at the costly toy as they 
