76 Tue Microscope. 
ment, lying at the bottom of the water, without any Motion or 
visible Motion or Life, being enclosed in a bi-valve Shell, which 
the animal can open or shut as it is inclined.” 
Speaking of the markings on the shell, he says: “ Several 
of them have a couple of very dark round spots, one whereof 
is seemingly placed on each side of the Shell.” He does not 
quite know what these “dark round spots” are. He “imag- 
ined them to be compact Ligaments, serving to open and shut 
the Shell, and corresponding to those of the Oysters, Muscles, 
Scallops, &c.” Or he supposes them to be “ concreted Bodies, 
similar to the Pearls bred in several kinds of Shell-Fish.” 
Obtaining microscopic life by means of infusions was well 
known at that time. The idea of ‘“ Pepper-Water” may be 
new to some microscopists. “ Put common black Pepper, 
grossly bruised into an open Vessel, to cover the bottom of it 
about half an inch or thereabouts, in thickness, and pour there- 
on Rain or River Water, till it rises above the Pepper one 
inch.” After a while a scum forms which contains “ millions 
of Animalcules, scarce discernable at first even by the greatest 
Magnifier, but continually growing bigger, till they come to 
their full size.” 
Among the most interesting microscopes in vogue at that 
time, were the “Double Reflecting Microscope” and the “Scroll 
Microscope.” The first named is a clumsy, awkward affair. It 
consists of a large tube supported by three brass pillars rising 
from a wooden pedestal. A smaller tube slides into the larger 
one, and from its bottom a still smaller one, to the end of which 
are screwed the ‘“ magnifiers,” i. e., objectives. At the top of | 
the large tube is an eye-piece. There is a circular plate of 
brass, fixed horizontally between the three pillars and below 
the larger tube, which serves as a stage. Below this stage in 
the base of the instrument is fixed a mirror, free to turn on its 
own axis, but fixed. 
Such was the microscope of the 18th century. Compare 
this instrument with one of the present day, and one can see 
what enormous strides microscopy has made during the last 
150 years. 
The “Scroll Microscope” was merely a pocket, simple 
microscope, fixed on a scroll of brass and illuminated by a 
mirror. 
