MICROSCOPIE IN GERMANY. 
493 
tail. From this apparatus the brass tish-pan was made which was 
in use for so long a period. The first apparatus for studying the 
circulation of blood in the frog was constructed in the year 1744. 
For observation it was combined with the sun microscope, and con¬ 
sisted of a frame upon which the animals were fastened with 
strings and pins. 
In 1782 Goeze discovered the compressium. He constructed 
two such instruments—one made of brass and a hollow capsule, 
with a glass bottom, within a moveable glass plate, which was 
fastened near the end, and capable of being extended by means 
of a spring. 
To examine the different kinds of object holders would carry 
too far. We will, however, simply remark here, that as early as 
1715 microscopes were made which had a rectilineal and revolving 
movement of the object by means of mechanical appliances. The 
appliances of Keppler were used to measure the object. The ob¬ 
server looked in the microscope with one eye, with the other upon 
a given scale or measure. This method was very favorable when 
the magnifying power of the microscope was known. Although 
this was not always the case, still it was a much better method than 
that of Leewenhock, who measured objects by comparing them 
with other known bodies or objects—such as a hair, a grain of 
sand, etc. In 1710 Prof. Theodor Ballhasar first recommended 
the use of the micrometer. The first micrometer, together with 
the seriros and Nitz micrometer, were made by Hertel. Several 
years later, however, they were brought into use by Benjamin 
Martin. In 1769 Brander made micrometers which were infin¬ 
itely better in their division than those of Hertel. 
•/ 
In examining the instruments for preparing the objects in use 
in the first period of microscopy, we shall observe that objects 
were examined in their natural condition. Small insects were 
stuck on pins, or placed between two mica plates, or held fast by 
pincers ; these were the only objects examined, at most the wings, 
the feelers, or the feet. Jan. Sell warn merdam made the first 
anatomical section. Although he was from the Netherlands, we 
shall loots more closely at bis method. He used the section table 
made by Samuel Mussehenbrock, a small scalpel, a delicate pair 
