CORRESPONDENCE. 
225 
to Germany. These instruments magnified, on an average, from 
70-130 times, and in their entire constructions were more useful 
for scientific observations. 
The first and oldest German microscope maker was Cosmus 
Conrad Cuno, of Augsburg. His microscopes were of a different 
construction, but were the equal of those of Leeuwenhoek, in me¬ 
chanical work. His lenses, however, were far inferior. 
As the work of cutting lenses was very tedious, small melted 
glass balls were used. These were first made in Germany by 
Frederick Schrader, and were really more advantageous than the 
first cut lenses. 
At the commencement of the eighteenth century, the simple 
microscope called the Wilson microscope, was brought in large 
numbers from England to Germany. In 1740, the maker added 
a glass for reflecting lights. At the same time, Johann Hathaniel 
Lieberkuhn of Berlin, made himself famous, through his excellent, 
powerful lenses, and in constructing an anatomical microscope, 
very similar to a microscope made by Lentmann, but which, in 
practical value, did not compare with it. 
A century after the discovery of the single microscope pro¬ 
gress had been made, through many contrivances, so that the dis¬ 
tance between object and lens could be regulated. The arrange¬ 
ments were primitive indeed if we judge them by our present me¬ 
chanism. Very small biconvex glasses were used as lenses, with 
a magnifying power of 2-300 times. Oftener small glass balls 
were used with a still greater magnifying power. By this manner 
of magnifying the light was not sufficient, so a lens was placed 
behind the object in order to concentrate the light upon it. Others 
proposed regulating the light by the use of diaphragms, to be ar¬ 
ranged according to the objects under observation. 
Lieberkiihn, improved illumination from above by the intro¬ 
duction of concave metallic mirrors. 
One obstacle still remained to the simple German microscope, 
the fact that the operator held his hand against the light, thereby 
hindering essentially many researches. This inconvenience was ? 
overcome by Joblot, through the introduction of a lens holder, 
with a jointed foot; and later, as already mentioned by Wilson 
