Lancaster daily intelligencer. [volume] (Lancaster, Pa.) 1864-1928, 1880-03-17
OUR MIuROsCOPICAL SOCIETY.


First Conference Meeting . Success.
Last evening the Microscopical society
held its first conference meeting, and there
was a full attendance of members, with a
number of invited guests, to hear the
opening exercises. The medical fraternity
is well represented on their list-no less
than seven of the twenty-five members
while the pulpit and the bar are also rep
resented.
The meeting was called to order at 8
o'clock, when the Rev. C. Elvin Houpt
delivered the opening address, in which he
clearly and succinctly set forth the object
of the organization, and dwelt at length
on the beauties of microscopical investiga-
tion which he aptly designated as the
science Of relaxation. He bade the society
God-speed in its voyage of discovery, and
to the word of salutation and welcome
added the wish that the connection of
each member with the association may re-
ward him renewedly by the widening of
the circle of his own knowledge, and the
enlargement of the pleasure he takes in
scientific study.
The secretary, Mr.. ]. D. Pyott, then
gave brief account of the origin of the
Scientific club, of which this society is the
first result, and predicted great things for
the future of both.
Then came the principal address Of the
evening, namely, lecture by the presi-
dent, DR.. J. w. Crumbaugh, on
The MicrOscODe
AS the derivation implies, this is an instru-
ment for viewing small things-objects too
minute to be seen by the naked eye. All
the different makes of microscope belong
to one of two classes the simple and the
compound.
The simple microscope has but one lens,
and is used principally for dissection OF
animal OR vegetable tissues; but as the
power increases, both spherical and chro-
matte alteration increase in like proportion.
The latter is characterized by producing
images whose edges are blurred and sur.
rounded with a colored border, produced
by the different refiangibility of the light
rays; for a lens (Which is an infinite series
of prisms) decomposes as we'll as refracts
light, and on account of this disper.
| sion, each color has different focus. This
| chromatic alteration is corrected by com.
| bining lenses of different substances and
curvatures. Spherical alteration is caused
by the greater refraction of rays passing
| through the edges of a lens whose aper
ture exceeds ten or twelve degrees. This
is corrected by cutting off the rays from
these edges by means of diaphragm, o.
The compound microscope is composed
of two portions-the optical and mechan
| ical. The optical portion consists of tht
mirror, the eye-piece and the objective
The mirror is simply reflector arranged
so as to adjust to different distances from
the stage, and reflect light from any angle
| It should be fiat on one side and cOncavt
on the other, to throw strong light di
rectly upon the object. The eye-piece con
sists of two plano-convex lenses, the flat
sides upwards, with a diaphragm of suit
able apsrtures between. The lens neares
the eye is called the eye-lens, the lower tn
field-lens. The use of the eye piece is t.
amplify the image as given by the objec
tive. The objective is a combination o
lenses in the lower part of the instrument
On its perfection chiefly depends the value
| of your microscope. Its lenses are so ar
ranged as to render the image achromati'
| and to give flat field. Unless corrected
| for spherical and chromatic alteration, thu
| objective is useless. A defect in the for
mer respect is detected by examining {
series of parallel lines, which should come
! up sharp and clear a defect in the othel
particular is at once seen in the coloreG
| edges-blue predominatins if under-cor-
ted, red if over-corrected. Flatness o.
field is tested by placing your stage mi
crofneter Ga glass plate ruled tohundredths
and thousandths of an inch) under the mi
croscope and focusing if all parts of the
field are in focus at one time, it is said tC
be flat-if the outer parts are blurred, the
glass is defective. These hints will enable
you know the glasses that you don't want.
The angle of aperture is the angle
formed by lines drawn from opposite
edges of the object glass to the focal
point. The rating of objectives by num-
bers has no relation to their focal distance,
the diameter of the anterior lens, the angle
of aperture, or the working distance. 1t
indicates the equivalent of single lens of
the same magnifying power as the combi-
nation-that is, a ! objective has the same
magnifying power as a single lens of !
inch focus. The most valuable for ordi-
nary use are the inch and inch these,
with couple of eye pieces and extra
lengths of tubing, give quite large range
of diameters. Working distance is the
distance between the object and the brass
rim protector around your objective.
The question IS often asked, How many
diameters can you get? The question
should be, What can you show with a
certain amplification If in working with
given power you get good definition and
resolution what is gained by increasing
your power? You could see no more ex-
cept perhaps defects in your objective.
The camera lucida is prism, mounted
in such way as to reflect the image upon
paper upon your table when the micro
scope is set horizontally and it's use is
that the image thus given can be traced.
It is an advantage to darken the part of
the table occupied by your paper.
Thus, the optical portion of the instru-
ment is really the microscope the remain
ing mechanical portion consists merely Of
arrangements for using the former with
greater facility. It consists of the stand,