CHOICE OF A MICKOSCOPE. 
95 
122. Illumination. For whatever purpose the microscope 
may be used, it is important to secure a pure and adequate illu- 
mination. The young microscopist will find daylight more 
easily managed, and more pleasant for the eyes, than artificial 
light. Even experienced microscopists can work longer and 
easier by good daylight, though they may have learned to 
manage artificial light so as to make it more available than 
daylight in bad weather. 
The best light is that reflected from white clouds, but light 
from fleeting clouds is troublesome to the eyes and requires 
constant moving of the mirror. Light from a luminous atmos- 
phere, near the horizon, is better than that near the zenith. 
The direct light of the sun cannot ordinarily be used for illu- 
minating the microscope, but the light of the sun, reflected 
from white houses, or from a white plastered wall, gives a soft 
and beautiful illumination. 
If possible, the microscope should be placed at a little dis- 
tance from a window on the side of the house, opposite to 
where the sun is shining. If artificial light is used, the Ger- 
man student’s lamp, constructed on the bird fountain principle, 
which gives excellent illumination, will be found as convenient 
as any other. If gas light is used, a pane of light blue glass 
placed between the light and the microscope, will take off the 
intense glare which is otherwise apt to injure the eyes. All 
flickering lights are very unpleasant in microscopic investiga- 
tions. Observations will generally be conducted with greater 
ease, when the body of the microscope is inclined. 
123. Ctioice of a Microscope. In choosing a microscope, 
reference should always be paid to the nature of the investiga- 
tions for which it is to be used. The most common error 
among inexperienced persons, is the idea that all objects can be 
satisfactorily examined with a high magnifying power. This 
is by no means correct, for it is often as desirable to ascertain 
the relations of different portions of an object, as to examine 
minutely any single part. Small crystals, insects, and parts of 
flowers, hairs, &c., which are readily obtained, are best studied 
with magnifying powers of from twenty to one hundred diame- 
ters. Young people in schools, academies, and private fami- 
lies, generally first examine this class of objects, and but few 
such persons can devote the requisite attention to prepare speci- 
mens with sufficient care to allow of their being examined with 
magnifying powers higher than three hundred and fifty 
diameters. 
The Educational Microscope, (page 25 of this Catalogue,) 
CATALOGUE OF ACHROMATIC MICROSCOPES. 
