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METHODS OF USING THE

Microscope, Camera-Lucida
and Solar Projector
FOR PURPOSES OF EXAMINATION AND

THE PRODUCTION OF
ILLUSTRATIONS.

By N. A. COBB

BEING THE FIRST ANNUAL REPORT OF THE DIVISION OF aaa
AND PHYSIOLOGY. EXPERIMENT STATION OF THE ; oe
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HAWAIIAN SUGAR PLANTERS’ ASSOCIATION oe ae , [-
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“Wd STH NOIVLS ANSASWISSAxXSa

METHODS OF USING THE

MICROSCOPE, CAMERA-LUCIDA ano SOLAR PROJECTOR

FOR PURPOSES OF EXAMINATION AND THE
PRODUCTION OF ILLUSTRATIONS.

By N. A. COBB

BEING THE First ANNUAL REPORT OF THE DIVISION OF PATHOLOGY AND PHYSIOLOGY,
EXPERIMENT STATION OF THE HAWAIIAN SUGAR PLANTERS’ ASSOCIATION.

To the Experiment Station Committee,
Hawaiian Sugar Planters’ Association :

It is using a misnomer to call this an Annual Report, inas-
much as the Division of Pathology and Physiology has been in
existence as a partially organized force for only about three
months, Under the circumstances the energies of the Division
have of course been devoted mainly to securing the proper
facilities for its work in the form of laboratory equipment and
land. I think I can not do better under the peculiar circum-
stances of the case than to describe at some little length the
more original of the features embodied in the Laboratory.

The nature of this building has been mentioned in the Annual
Report of the Chairman of the Committee on Experiment Sta-
tions, and the illustrations inserted there and elsewhere in this
report give a good idea of its general appearance, both ex-
ternally and internally. The features to which I will call partic-
ular attention are those found in the Microscope Room, Illus-
tration Room, and Dark Room. ;

THE MICROSCOPE ROOM.

For many years it has been customary in the best laboratories
to mount various instruments of precision upon pillars of stone
or masonry deeply imbedded in wells in the ground and passing
upward through the floors of the laboratory without contact.
The object of this arrangement is to prevent tremors, which are
of constant and inevitable occurrence in an inhabited building,
from being transmitted to the instrument; the earth receives
these tremors, and, within the limits of the precision of the in-
strument, they are nullified. Galvanometers, seismographs,
balances and other instruments are mounted in this man-
ner. It is not often that the microscope has received such
special attention, but wherever high powers are used and espe-
cially when photo-micrographs are being prepared, or whenever
high power camera lucida drawings are being made, the reduc-
tion of vibration is an important factor in the success of the

2

work. For many years the writer has had microscopes mount-
ed in this way and hereby testifies strongly in favor of this
method of using the microscope. The system is exemplified in
the Laboratory of the Division of Pathology and Physiology,
and as experience has added improvements to each successive
plant erected, it may be worth while to describe this recent
outfit. ;

The plan is carried out in cement and steel. See Fig. 1. Below
the building is a large block of cement weighing several tons. In
this block of cement three T-girders, two of which are approx-
imately eight inches in each dimension, are imbedded vertically
to the depth of about four feet. The central girder carries
the microscope, together with certain accessory apparatus
connected with the illumination of the object. This girder is much
smaller and shorter than the other two, extending only about
eighteen inches above the floor of the microscope room, The
other two girders are mates and extend to within about eighteen
inches of the ceiling of the room; in other words, project upward
into the room about eleven feet. The building being constructed
of wood, the floors were laid about the pillars after they had
been set in the cement and the whole structure was then given
sufficient time to settle into its permanent position. This usually
occurs in the course of a few months. When everything is set-
tled into position, an ordinary key-hole saw is run through the
floor entirely around the contours of the girders, so that at the
end of the sawing operation the girder entirely clears the floor-
ing and floor covring by the width of a saw blade. See 3, 43,
&c., Fig. 1.

Needless to say the object of these girders is to afford attach-
ment for all the riecessary apparatus connected with the micro-
scope. The girders at every part clear the walls of the building
by a fair margin. It is however best to place all the girders as
close to the microscope window as is convenient, The reason
for this will be explained on a subsequent page. In the present
instance, the distance between the girders and the window
casings is about one inch. The general principle on which
the accessory apparatus is attached to the girders is that
of sliding metal sleeves that may be clamped in any desired posi-
tion. A sleeve of one-sixteenth-inch sheet metal surrounds the
small central girder and projects outwards, that is toward
the observer, sufficiently to form a base on which the micro-
scope may rest. This base is from one to two times larger than
the horse-shoe base of the microscope. This gives a sufficient
ee a space so that the microscope can be readily arranged

nt classes of work,—moved sideways in either direction,
or forward, or backward. The sleeve carrying the microscope

Adozesoqey uFe]Ay
ADOTOISAHAG GNY ADOTOHAVdG AO NOISIAIA

ne FIG. I.—MICROSCOPIST’S OUTFIT.
1, 1, 1. Pulleys for the sash cords 2.
2, 2. Steel sash cords for the slides 12 3 : ”
and 21. 3, 8. Two vertical steel girders :
passing through the floor without contact,
imbedded in several tons of cement under
the building. 4, 4.. Steel sash cords, same
as 2. 5. Wooden frame-work to stiffen the
girders 3, 3. 6, 6. The two upper opaque
sashes to the side windows of the bay.
7, 7. Sash weights counterbalancing the
cross-arms 12 and 21. 8. One of the two
Similar light-proof roller blinds. 9, 9.
Anti-friction bearing for the arms bolted to
the cross-piece 12. 10. Anti-friction bear-
ings for the arms of the cross-piece 21.
11. Lower opaque wooden sash of :
the left hand window. 12. Cross-
piece for the attachment of the ca-
mera 18 and the camera lucida
prism 24. 13. Screw clamp to
cross - piece 12.
14, Lower o-
paque wooden

tached to arm 21. 20. Vertically slid-
ing head-rest. 21. Wooden cross-arm
supporting miscroscope camera 19, and
head-rest 20, and drop slide 32. 22.
Battery of microscope using direct sky-
light. 23. Screw clamp to cross-arm
21. 24. Large 45 degree camera
lucida prism. 25. Location of the ca-
mera lucida drawing, vertically adjust-
able by means of steel cord and sash
weights similar to 7. 26. Pillow to
head-rest. 27. Wide thin metal cur-
tain stick to the inside roller blind 8.
28. Ways for the horizontal thin metal
slide 29. 29. Thin metal slide with dia-
mond shaped opening 31. 30. Small
camera lucida prism of the usual pat-
tern. 31. Diamond shaped opening in
the slide 29. 82. Thin opaque drop slide
adjustable vertically through foot power
by means of simple pulleys
located behind 17 and the
foot power 40, 41 and 42.

sash to right
hand bay win-
dow. 15. Slot
in which the ca-
mera lucida arm
17 slides hori-
zontally. 16.
Clamp to the
cross-arm 21.
17. Arm for the
support of the
camera lucida
prism 24. 18.
Ordinary camera
attached to arm
12. 19. Micro-
scope camera at-

with ground glass and opened and closed b

and vertically adjustable on the pillar 38.

bedded in several tons of cement under the buildin
for the control of drop slide 32 by means of the string passing around the pulley 42. 41.
with sand-paper to give sole of boot efficient grip.
lowers the drop slide 32.

height of floor. 44.

The weight of drop slide 32 exactly counteracts the spring of the roller 41. 43.
Steel sleeve sliding vertically on left hand girder and affording attachment for table 33. 45.

y_means of slide 82 and foot power 40, 41, and 48, 37.
Steel pillar for support of microscope, passing through floor without contact and im-

33. Left hand
adjustable 1eg-
of-mutton shap-
ed_ table. 34.
Right hand ad-
justable leg-of-
mutton shaped
table. 35. O-
paque dark
cloth enclosing
sub-stage of mi-
eroscope, pre-
venting access of
extraneous light.
36. Aperture for
the admission of
light; glazed
Steel sleeve carrying microscope

g. 39. Aperture in floor for the passage of girder 38. 40. Svring-roller foot power
Spring roller of ordinary pattern covered
42. Pulley turned by foot power and winding or unwinding the string which raises or
Left hand steel girder at
Steel sleeve slid-

ing vertically on right hand girder and affording attachment for table 34.

5

is clamped to its pillar by three set-screws, and by means of this
simple arrangement the microscope can be fixed high or low
to suit different operators and different classes of work. When,
for instance, micro-photographs are being taken, it is most con-
venient to drop the sleeve to its lowest limit, so that the micro-
scope will rest on a base about fifteen inches above the floor.
For most photo-micrographic work this will enable the operator
to bring the focussing plate of the camera (19 Fig. 1) low enough
to render it unnecessary for the operator to have any special step-
ladder to assist him in obtaining an accurate focus. On the other
hand, when it is necessary to place the microscope high and the
camera lucida table low, one can obtain a distance as great as two
and one-half feet between the level of the eye-piece of the micro-
scope atid the drawing table. This, together with the peculiar
camera lucida, which will be described later on, enables one to
make his original sketches of such a size as to allow for that
liberal reduction in the subsequent photographic process which
gives the best results for book illustrations. The sleeve which
carries the microscope also carries a wooden front as wide as
the microscope window and about two feet deep, in other words
about three feet by two feet. This screen, which of course slides
up and down with the microscope and its sleeve, carries two
apertures. One of these apertures is in front of the microscope
mirror and is designed to allow the light from the special out-
door illuminating screen to strike the mirror and pass through
the microscope. The second aperture is of much larger size
and is glazed with ground glass and is opened or closed as de-
sired by means of a ‘hanging slide worked by foot-power. The
object of this second opening is to secure a correct illumination
on the drawing board when the camera lucida is in use. See Fig.
T.

We will next pass to a description of the microscope win-
dow. This faces the sun, and preferably faces precisely southa
It is so fitted with light-proof roller blinds that the light
may be entirely shut off or may be allowed full access, The
roller blinds slide in lateral grooves ten inches deep. The depth
of these grooves must be sufficient to prevent the blinds belly-
ing through the action of the wind. It is found when a window
is tightly closed with flexible blinds as is the case in this special
microscope window, that the pressure of the wind is sufficient
to cause considerable inconvenience unless the edges of these
roller blinds are held in deep grooves. ‘Should it be necessary
to make a further provision against the bellying of the blinds
they may be stiffened from place to place with one-sixteenth-
inch wooden laths; or wires may be strung across the window.
The blinds may be of any Opaque material, but if they are very

6

long, preferably of some thin material. The writer has oe
that ordinary green opaque window blinds can be sized las
so as to become practically light-proof, and as it 1s advisable in
constructing a hght trap to have two blinds, he finds that with
two such blinds the lignt 1s wholly excluded, and if necessary
the room can be used as a photographic dark room, The wood-
en rollers used are of the ordinary pattern and present no spe-
cial peculiarity. hey are built in or boxed in at the top in a
light-tight manner. aoa

We turn next to the various sleeves sliding on the long u,-
right girders. Of these one of the most important is the right-
hand lower sleeve which carries a leg-of-mutton shaped table
for use in connection with the production of camera luada
drawings. This sleeve as well as all the others, is balanced with a —
sash-weight, so that it moves with the utmost freedom either up
or down through a space of about four feet. The table may
therefore be placed within fifteen inches of the floor, or it may
be raised to a distance of three feet. This abjustability is found to
be highly convenient in the production of camera lucida draw-
ings of definite magnification, The peculiar shape of the table
has been evolved from practical experience during many years.
In general, its form is such that when taken together with its
mate on the other side of the microscope, it presents a semi-
circular curvature which gives the investigator a free play for
hands and body. This table is painted black, as are all the other
accessories used in this system. See 32, 34, Fig. 1.

Turning to the left-hand side of the microscope, we find an
entirely similar and symmetrical sleeve and table, which however
is used for a very different purpose. This sleeve carries the
mate to the camera lucida table and of course, in the case of a
left-handed operator, could be used in the same way as the right-
hand table would be used by a right-handed operator. The
tual position for the left-hand table is about on a level with
the microscope stage. This height is found to be convenient
for several reasons; first, under ordinary circumstances, it is
about ordinary table height and is convenient for supporting the
dissecting microscope, which, as explained later on, has a special
illumination of its own. Thus in the preparation and examina-
ee objects, the dissecting stand is as close as possible
ae fe : dae wee stand and the objects may be transferred

9 the other with the greatest convenience; a second
Beko: for having the left-hand table on a level with the stage
a oie ee te is that the preparations may be moved on and
ge of the microscope with the least danger and with
the greatest facility. A third reason is that in this position the

7

left forearm finds it a most convenient rest in working the fine
adjustment screw. In addition to the three sleeves already de-
scribed, the long girders carry two cross-pieces for the attach-
ment of various accessories. These wooden cross-pieces slide
up and down and are weighted with sash weights so that their
adjustment may be quickly and easily accomplished. In order
that the friction on the girders may not cause any inconvenience,
arms extend upward from these cross-pieces for the purpose of
carrying pulleys which are in contact with the edges of the
girder and so reduce the friction. These cross-pieces are clamp-
ed in position by set-screws at the side. It will be at once evi-
dent that these cross-pieces may be used for the attachment
of a variety of accessories. Among the more important of these
is the microscope camera. See 19, Fig. 1. This hangs above the
microscope and is ever in readiness for instant use. The camera
itself presents no very peculiar features. It is of course a vertical
pattern carrying the exposed photographic plate in a horizontal
position. It cannot be used in a horizontal position. Experience
has shown that the vertical position has very many advantages,
and that if one is confined to a single outfit, the vertical outfit is
the better, providing its attachment can be of the nature here
described. In obtaining the focus, the cross-piece carrying the
camera is loosened by unclamping the side screws and is then
moved upward and downward against the sash weights which
counterbalance it. A scale is marked on the girders so that the
various magnifications are at once obtainable, or they may be ob-
tained by special measurement in each case. The apparatus never
needs any levelling, being, as before said, constantly ready for
use. The operator loosens two hooks and the camera drops
instantly into position. The whole is ready for use in a few
seconds’ time. ‘If the photograph is being taken with a high
power and the illumination is therefore weak, and the exposure
consequently long, one leaves his instrument during the expos-
ure with the greatest confidence that nothing can disturb it.
Any tremors in the building will not be received either by the
microscope or the photographic plate.

A second attachment of great importance for the production
of illustrations is the

CAMERA LUCIDA.

This presents a number of peculiarities. Fig. 1, 17, 24. The
history of the camera lucida is a very interesting one. It is impos-
sible to go into its details here, but nothing is clearer than that
this instrument is one of great importance to the microscopist,
and its history is in accordance with this fact. The utmost in-

8

genuity has been exercised to produce an instrument by means of
which sketches of small objects can be made with the aid of the
microscope. The necessity for this class of work is very great.
The photographic camera does not materially assist us with most
subjects. Only in the case of exceedingly thin sections or natu-
ral objects of great thinness is a photomicrograph satisfactory.
In all other cases in order to fully elucidate the structure by
means of an illustration it is necessary to obtain the appearance
at different depths in the preparation. This can only be done by
focussing the microscope for each particular portion of the
structure. This fact, thus hastily explained, is what makes it
absolutely necessary to use a camera lucida for the proper rep-
resentation of most microscopic objects. This fundamental
necessity is what has given rise to the many patterns which the
camera lucida has taken on during the course of its history.
The first instrument was an extremely simple one. From time
to time improvements and additions have been made until at
the present time the instruments issued by the best makers are
marvels of ingenuity and workmanship. In fact, in the writer’s
opinion they are almost too ingenious, for it appears to him
that the various additions which have been made to the camera
lucida during recent years, while they do accomplish the object
aimed at, do so in an unsatisfactory manner.

In order to produce a good camera lucida drawing, it is
necessary to Nave a certain degree of light passing through
the microscope enabling the operator to see the object with the
greatest possible clearness. It next becomes necessary to so
modify the light from the drawing board as to enable him to see
his drawing point with the greatest possible clearness, Now,
with most objects it is not possible to secure this adjustment
once for all, for all portions of the drawing. Different portions
of the object emit different amounts of light, and, as the light
varies, it 1s necessary, in order that the drawing may be made
with the greatest precision and facility, that the light from the
drawing board should be modified accordingly. The accomplish-
ment of this end has been sought in a variety of ways, and this
more than any other one thing has added to the complexity of
the modern camera lucida. When the modern instrument is in
good order, it does, as we have admitted, in a way accomplish
its object. The difficulty is that it is easily thrown out of adjust-
ment, and easily becomes soiled and dusty so as to be a hind-
rance rather than a help. Again, no device has yet been furnish-
ed by manufacturers which enables one to modify the light ex-
cept by a series of steps. It is usual to insert or remove a cer-
tain number of tinted glasses until the right degree of light has

9

been secured. It often happens that the precise tint required
can not be secured at all. In any case by this method there is
always being inserted between the eye and the object, various
pieces of apparatus which can not be regarded as other than
necessary evils. It is needless to go into the particulars of
instruments made by different makers. What has been said has
a general application. A second defect presented by many of
the camera lucidas, is the doub!e reflection due to a silvered mir-
ror. The thickness of this mirror has been carefully adjusted in
order, as far as possible, to superimpose the various images one
on the other, but it is impossible to get rid of the double reflec-
tion and while this can be tolerated for a short time, if the in-
strument is in use for a considerable length of time, say several
hours, this double reflection of the pencil point becomes very
tiresome to the eye. ‘

Any form of camera lucida is an instrument well-calculated
for the destruction of eye-sight. The writer has during
many years of experience been endeavoring to reduce the
injury to eye-sight in connection with the use of the camera
lucida, and the following suggestions, embodied in the out-
fit ‘here described, are the result of his experiences. In the
first place, he has substituted for the ordinary mirror a 45°
prism. Fig. 1, 24. The advantages obtained by this substitu-
tion are as follows: 1. The prism may be of any desired size
so that it may be mounted at a considerable distance from
the eye-piece of the microscope. This secures an increased
magnification of the drawing, and the advisability of this in-
creased magnification will be dwelt upon on a subsequent page.
2. A second advantage in the use of the prism as a reflector is
the disappearance of the double reflection, and the securing of a
total reflection. The light passes from the drawing-point
through the lower face of the prism in a nearly perpendicular
direction and with very little loss. ‘It is then totally reflected
from the oblique face and passes outward nearly at right angles
to the vertical face, again with very slight diminution. The
loss of light is therefore considerably less than in the case of
the usual mirror, in addition to the securing of a totaf reflection
destitute of doubles. 3. A third advantage and one of consider-
able importance is the stability of the apparatus there described;
it rarely gets out of register.

The second modification is that which thas been referred to on
a previous page, as the blind worked by foot-power. Fig. 1, 32.
The object of this blind is to illuminate the drawing with any de-
gree of light at an instant’s notice and to do this without in any
way disturbing the adjustment of any part of the microscope or

10

camera lucida. This is a matter of very great importance in the
rapid production of good camera lucida drawings. — It olten~
happens that the hght coming through the instrument is so faint
that it is only by shutting the light quite off from the drawing
that the investigator can see the details of the structures to be
sketched. This darkening has in the past been accomplished
in various ways. It has for instance been accomplished by hav-
ing a pencil on the butt end of which is a feather to be flirted
in between the eye and the drawing board so as to oblit-
erate the image of the latter. There are other methods of
accomplishing the same end. With the foot-power arrange-
ment, the light is shut off or let on without the operator’s dis-
turbing the position of his body or his drawing-point. More-
over, the light can be so modified as to instantly bring about
that adjustment which is most favorable for any particular part
of the sketch. To describe the whole operation briefly, we may
say that the operator’s left hand rests on the ‘eft-hand leg-of-
mutton table on a level with the fine adjustment of the micro-
scope. His left hand therefore is in a position to work the fine
adjustment screw with the greatest ease and facility, and the
most careful adjustments of focus can be easily accomplished.
His right hand carrying the drawing-point rests on the drawing
board and is engaged in the production of the sketch. As the
light required for the various portions of the drawing varies he
can by a slight movement of his right foot, which in no
way disturbs either of his hands, and in no way disturbs
the equilibrium of the instruments, effect the desired illu-
mination of the drawing. It is found that the drawing
surface best adapted to the production of camera lucida
drawings is a dark, and, preferably, black surface. On this.
surface a white drawing point should be used. For most objects
this is a considerable improvement over the ordinary pencil used
on white paper, as wil be at once admitted by any one who
makes a trial. The method found most effective in this labor-
atory is that of using a thin black tissue-paper which is blued
on the under side. A piece of enameled board of suitable size
for the drawing is placed on the drawing board, i. e., the right-
hand leg-of-mutton table, and it is then covered with the black
see with the blue side down. A tracing is now made
ae ey ivory point. This results in the production of a
ne drawing on the enameled board. This sketch is put
remo ais reference, or for the production of a finished
ahiect = dees degree or may be finished up at once, The
spemraties aoe in this blue sketch is a sufficiently good
he object to be illustrated which sha‘l have

ny

es

sufficient size to admit of a liberal reduction when the drawing
is photographed on metal preparatory to etching. Thus, if it
is desired to publish an illustration having a magnification of
500 diameters, it is advisable to produce a blue sketch at from
1,000 to 2,000 diameters. This is easily accomplished with the
apparatus that has been described. By placing the prism reflect-
or at a considerable horizontal distance from the eye-piece of the
microscope, say one foot, and lowering the right hand leg-of-
mutton table sufficiently, magnifications of liberal dimensions are
easily secured. Needless to say the production of a large coarse
drawing is an easier matter than the production of the same
drawing on a smaller scale, so that the operation is not only bet-
ter, but considerably easier if carried out in the manner describ-
ed. It is unnecessary to go into the details of converting the blue
sketch into a pen and ink drawing. These present no peculiari-
ties. It ought perhaps to be mentioned that the object of using
the blue color is to avoid trouble through the alterations that
may be necessary in finishing the drawing. Any light blue lines
which are left on the enameled board need not be removed, as
they do not affect the sensitive photographic film sufficiently to
cause any intonvenience in the production of an etched block.
The black tissue paper mentioned is produced by inking ordin-
ary tissue. The ordinary blue carbon paper gives too dark a
blue to meet the requirements. The blackened tissue is rubbed
on one side with dry Prussian b!ue powder. This gives a light.
blue tracing.

At an earlier stage it has been mentioned that all the acces-
sories in connection with the microscope are painted black. In
addition to this precaution, arrangements are madé such that
the room itself can be darkened, in fact, converted into a photo-
graphic dark-room at will. This object is secured by having all
the window blind connections light-tight. The oblong aperture, :
about five inches by eight inches, through which the micro-
scope receives its light is screened by means of several thick-
nesses of flexible black cloth made into the form of a sleeve.
This cloth sleeve attached around the perimeter of the open-
ing, is notched above so that it surrounds the microscope
just beneath the stage and buttons onto one of the screws at
the back of the microscope. No light reaches the eye ex-
cept that which comes through the instrument. If, now, the
slide in front of the large glazed aperture be closed and the room
be darkened, the operator sits.in absolute darkness. Any one
who has had experience with a photographic dark-room, must
have observed how after a period of from five to ten minutes
therein the eye becomes accustomed to the darkness of the room

I2

and is able to distinguish objects much more readily than at first.
This is a principle which can be utilized to very great advantage
in connection with high-power microscope work, 'In fact, the
writer is of the opinion that it is this contrast between the ex-
ternal and internal illumination which leads so many operators
to use artificial light, and even in some cases to prefer working
in the evening. Certain it is that if the surrounding light is
dim and the eye is allowed to adjust itself to this dimness, then
on looking through the microscope, details may be seen much
more clearly than in any other way. It is often painful to wit-
ness the unconscious efforts of microscopists to bring about this
condition as fully as possible by means of awkard attitudes and
facial expression. It is not at all uncommon to see the micro-
scope placed in a glare of light with a strong light beating on the
top of the object and confusingly reflected up through the micro-
scope, and to see the operator sitting in a cramped position,
bringing his head over the top of the instrument so as to shade
his eye as much as possible and then often drawing the eye-brow
down to assist in the same object. I take it that all this is sim-
ply an unconscious effort to give the eye the benefit of a weak
extraneous light. With the present apparatus, these difficulties
disappear. The room is darkened. All light which could pos-
sibly get to the operator’s eye is excluded, except that which
comes through the microscope. There is no light coming upon
the top of his object to cause confusing reflections in the micro-
scope. The image is as clear as it can be made and the eye is
given every facility to see this image and is distracted by no
others, Needless to say the apparatus is a daylight apparatus.
It hardly seems necessary to argue that as daylight is the
light which has developed the human eye it is the light to
which it is best adapted. Images produced by diffused day
light must be the best that can be produced on the retina of the
human eye. This seems a sufficient argument for the use of
daylight and a sufficient explanation of its superiority to every
other light. However, when all this is said, it is not possible to
always secure and contro] this natural light so as to get the best
results. The following contrivances are such as experience has
shown the writer to be very useful for this purpose, especially
By suing climates. Outside of the microscope window a univer-
sally adjustable white screen is placed in a sunny position, pre-
ferably not more than ten feet away. The surface of this screen
may be of any white material. It can be made of wood, painted
white, or lined with plaster of Paris, or, what to the writer seems
a:most equally good, a plain wooden screen covered with several
thicknesses of bleached cotton cloth. It is better if this screen can

13

be adjusted from the interior of the microscope room, but this is
not essential. If a small mirror be attached to the screen, it will
indicate the position of the screen that will reflect to the micro-
scope mirror a maximum of white light. Place the screen so
that the flash of sunlight from the mirrof strikes in the vicinity
of the microscope. Then of course, the whole of the screen will
be in a corresponding position and will be reflecting a maximum
of light. It is found that if the screen be placed in this position
for several hours the light from it remains practically con-
stant, so that while an adjustment by cords from the interior is
a convenience, it is not a very great necessity. If an adjustable
screen is not available, it is generally best to arrange one or
two fixed screens and thus accomplish the same object, one
screen for morning and another for afternoon. The light
from a blue sky is not a satisfactory light. A white cloud gives
a very good light, but clouds-are such fickle things that it is not
wise to rely upon them where the microscope is in constant use.
It is much preferable to construct a screen that will be avail-
able in a fixed position whenever the sun shines. When the
sun does not shine the sky must serve.

It remains to say a few words in regard to the dissecting
microscope. This, as before mentioned, rests on the left hand
sliding table. The main microscope window is flanked by two
narrower windows, (forming a “bay”) each of which is fitted with
opaque wooden screens sliding up and down with sash weights.
Whenever necessary, these screens can be raised and the light
necessary for the preparation of objects secured. The object
ready for examination, the screen is dropped, the room is dark-
ened and the examination with the compound microscope pro-
ceeds. The screens just described have a second purpose in the
carriage of batteries of accessory microscopes. It is often con-
venient in making comparisons to have several microscopes in
operation at one time, even where, on account of the cost, it is
not feasible to furnish complete outfits. To meet this end, cylin-
drical barrels capable of carrying objectives and eye-pieces are
mounted in batteries on the screens and are pointed at the sky.
The outfit that is found most convenient for each unit of this
battery is as follows: a rather high-power eye-piece, a barrel 160
mm. long capable of carrying the ordinary objective, and two
objectives, one of which is a moderate power corresponding to a
one-sixth Bausch and Lomb or a Zeiss “D,”’ and the other a
two-thirds objective or Zeiss “A.” ‘In the wooden stage, a small
section of tubing of the same size, and capable of carrying an
objective, is used to carry the lower power of the two objectives,
It is found that by pairing these objectives with care the low

14

power objective furnishes a first-class achromatic condenser for
the high power. It is surprising what good results may be ob-
tained with this simple apparatus. ;
The other features of the outfit are sufficientlv displayed in
the illustrations, The‘ rotating tables are of the usual type,
though above the usual size. They carry five by eight swing
drawers and hanging shelves for books and instruments.

THE DARK ROOM.

A peculiarity of the Division dark room that deserves men-
tion is its illumination. This is carried out on a plan that has
often been adopted for small dark-room lamps, but has not
hitherto, so far as the writer knows, been carried out on a large
scale adapted to daylight as well as artificial light.

The non-actinic or “safe” light for the dark room is obtained
by passing daylight through suitable so!utions, and the illumina-
tion is from above after the manner of numerous patterns of
small dark-room lamps. The dark room window is placed some-
what higher than is usual and its upper sash is boxed in in a
light-tight manner. The box is prismatic in form: one side is
parallel to the side of the dark room, in fact coincides with it;
another is perpendicular to the side of the dark room and forms
the horizontal bottom of the box, while a third is at an angle
of 45°, such that when a mirrow is fastened on its inner surface
it reflects the sky light, which comes through the window and
throws it downward upon the dark room sink and developing
board. On the bottom of this prismatic box, there rests a tray,
or a number of trays nested one over another, for the reception
of the various colored fluids used as light screens. One of the
most useful of these fluids is a concentrated solution of bichro-
mate of potash. ‘It is found that ordinary daylight or sunlight
on being passed through from eight to twelve inches of con-
centrated solution of bichromate of potash is a very sufficient and
satisfactory light in the dark room, especially when it is reflected
from above in the manner described.* The mirror used for re-
flecting the light downwards is preferably of corrugated glass,
though plain glass answers the purpose. The box contains an
electric or gas light so that it is available for evening work. The
amount of comfort to be gained from an ample illumination in
the dark room is something that should not be overlooked, as
the frequent passage from the dark room to an illuminated room
1s a trying matter, even for the best of eye-sight. The amount
of illumination which may be secured by adoptine the plan here
described may be readily judged when it is said that during de-

* A still better arrangement is to have a glass aquarium full of the solution placed

directly in f : al 4 s : :
downward pes eet aa the light passing through it being afterwards reflected

15 .

velopment ordinary type can be read with the greatest ease, so
that it is rather a misnomer to call the room a “dark” room.

THE ILLUSTRATION ROOM.

Several of the rooms of the Laboratory of the Division of
Pathology and Physiology are specially fitted up for the use
of solar projecting apparatus. This projectine apparatus is pri-
marily for the purpose of projecting negatives and microscope
preparations from which illustrations are to be prepared, and in
some ways the apparatus thus used takes the place of the ordi-
nary camera lucida, and for the class of objects to which it is
suitable, it affords many advantages over the camera lucida, It
is however limited in its application so far as the microscope is
concerned as it is impossible to use the highest powers of the
microscope in this manner. A second use to which the projector
will be put is the projection of images of microscopic objects
which are under examination and which it is desired to show
to- more than one person at a time to facilitate discussion and
study. Needless to say the projector can be used in the same
manner as an ordinary stereopticon or magic lantern, with the
advantage that, as sunlight is more powerful than any artificial
light, much better images may be secured. It is also needless
to say that the instrument has the inevitable drawback that it
can be used only when the sun shines.

When the instrument is used in the production of illustrations,
it is customary to project the negative, or preparation, upon a
glass screen of special character. The object of the screen is to
secure to the artist that freedom of movement which comes
from relieving him of the drawback which is usually presented
by. the shadow of his own hand and person. The projector
has often been used for the production of illustrations, but
the writer is not aware that the present method has been
hitherto exploited, except in his own private laboratory,
namely: the use of so powerful a light as to enable the operator
to throw the image through ordinary cartridge paper, thus en-
“bling him to work on what may be called the backside of the
projection. This method is an expeditious one and is a very
great gain indeed from an artistic point of view. It is a gain from
almost any point of view, but it particularly gives a freedom of
treatment that has to be experienced to be fully understood. It
is found that the projector when used in this way facilitates the
production of illustrations from negatives so poor that they
would not make a print suitable for reproduction by the half-
tone or any other process. Furthermore, it often happens that

16

negatives contain objectionable features that it is not anete
should appear in the illustrations. When a drawing 1s ete

ed from the projection of such a negative, the objectionable
features can be omitted. Again, the desirable features of sev-
eral negatives can be combined and in this way results can a.
procured which would be procurabie in no other. As to the
details of the apparatus, little need be said so far as the pro-
jector itself is concerned. It is of the ordinary, pattern consist-
ing of an adjustible mirror capable of throwing the parallel rays
of sunlight through a large condensing lens. The cone of light
produced in this manner is passed through the negative or
preparation and the light is brought to a focus on the screen by
means of an objective. This objective may be a simple cheap
meniscus, or may be a photographic lens, or a microscope
objective. All these forms are in use in the illustration-
room, It is more necessary to give the details of the screen up-
on which the projection is received and upon the surface of
which the artist produces his drawing. This screen is borne
between two uprights about seven feet high, set on four castors
placed sufficiently far apart to give the apparatus a firm support.
After the apparatus has been rolled into position, four screw-legs
are screwed downward and the apparatus is thus raised off its
castors and placed on four legs, and is then sufficiently firm to
resist all the pressure that is brought to bear upon it. The
screen proper is pivoted between the two tall uprights, and
by means of a series of notches is adjustable in the vertical
direction. The screen consists, to all intents and purposes,
of a very large glazed window sash having the glass flush
with the framework. The sides of this sash or frame are
sufficiently strong to give it firmness and when the neces-
sary angle is secured, a pair of clamps secures the screen
from any mal-adjustment. At each end of the screen, two long
pieces are hinged in such a way as to facilitate the manipulation
of the paper upon which the artist works. These long narrow
pieces are four feet long and one inch square and are hinged at
the top of the screen and pass downward everywhere equi-
distant from the side of the frame, this distance being about
three-fourths of an inch, At the lower end, these pieces are con-
stantly pulled inward or toward the glass, by spiral springs, The
under surface of each of these long pieces is lined with sand-
paper. If now a long soft wooden stick suitable for the attach-
ment of drawing paper be placed across the glass face of the
screen, which as before remarked is flush with the frame, and
be Passed under the sand-paper surfaces, these latter will grip it
with great firmness, and it will be found impossible to move it

Solar camera as used
to facilitate the pro-
duction of illustrations
from negatives and from
transparent
objects.

it
we

RY
wt AS:
SS

Fig. 2. 1, steel girder to left of window affording part of the support to
the ordinary camera 3; 2, cross-piece supporting camera 3; 4, support for camera
lucida, same being here represented as attached to an ordinary lens carrier; 5,
vertically adjustible horizontal platform; 6, drawing board; 7, horizontal ways
for 6; 8, object in position to be drawn natural size; 9, mirror of ordinary camera
lucida; 10, 11, camera lucida support; 12, light-tight roller-blind used, when
unrolled as a diaphragm for the cone of light from the projector: 13, solar-pro-
jector set in special window casing near floor; 14, the negative being projected
at 23; 15, 15, uprights carrying the adjustable sheet of glass on which the draw-
ing 23 is being produced from the negative 14; 16, wooden frame for sheet of
glass 18; 17, metal braces by which the frame 16 may be clamped at the required
angle; 18, sheet of glass through which as well as through the paper 22,
the image is viewed; 19, roller blinds to shut off extra light; 20, 21,
sticks to which the drawing paper is attached with drawing tacks, these sticks
being easily adjustable under the sand-paper-lined wooden springs-bars 24; 22,
drawing paper; 23, image being drawn; 24, wooden bar lined with sandpaper and
hinged at 25 and constantly pulled inward by a spiral spring at 26, so as to lightly
but firmly grip the sticks 20, 21; 27, screw legs on which after the apparatus has
been adjusted it can be raised so as to remain firm during the subsequent opera-
tions of focussing and drawing; 28, one of the four castors on which the whole
apparatus is adjustable back and forward on the floor to vary the magnication.

DIVISION OF PATHOLOGY AND PHYSIOLOGY
Combined Work-Room, Library, Museum and Meeting-Room, Main Laboratory

19

without the use of considerable force. It is to the under sur-
face of this transverse piece thus held in position by the sand-
paper surfaces at the ends of the screen, that the drawing paper
is attached by means of ordinary thumb tacks. This provision
is advisable, as in the use of the projector it is often necessary
to bring the drawing into register, or to change the register
somewhat. By slightly lifting the sand-paper surfaces, the paper
is easily changed in position to accommodate any change of
register. It is usual to make two punctures on the negative as’
register marks. As it is anticipated that this apparatus will come
into much wider use, it may not be out of place to mention a
number of points which experience has shown to be worthy of
imitation or improvement. The light is usually a very strong
one and in consequence the operator is most strongly illumin-
ated. It is therefore desirable that he should wear dark-
colored clothing, otherwise the reflections from his person will
cause considerable interference. It is also desirable to have the
room as dark as it can be conveniently made—the darker the
better, especially when high power magnifications are in pro-
gress. When the finest detail is to be drawn, it is also advisable
to arrange at the top of the screen a roller blind carrying an
absolutely opaque blind with an aperture not much larger than
will give freedom of movement to the hand in drawing, say
from four to eight inches across. This shuts out all of the extra
illumination and the eye will then accommodate itself in such a
manner that any fine detail is much more readily seen. It is
also desirable to have a drop blind by which the whole of the
light may be instantly shut off, as well as a light at the back
which can be also instantly let on so as to give the operator a
very distinct notion of what he is producing. For it must be
pointed out that when the drawing is being made, it is not
easy for the operator to see his work, especially if he is working
with a blue pencil, as is often the case if the drawing is to be
afterwards finished up, photographed, and reduced for illus-
tration purposes,

The illustration room is also furnished with an ordinary
camera working on vertical uprights of the same character as
those already described in connection with the microscope win-
dow. These are a second pair of steel girders imbedded in
cement below the building and coming through the floor with-
out contact. It is found that a great variety of objects are more
conveniently photographed by using the camera in this manner
than in any other, though of course it is necessary for many
classes of objects to use it in the usual way. To facilitate the
production of the necessary backgrounds, a well is provided.

20

This consists of an approximately cubical box, the sides of which
are merely grooved framework in which run a set of opaque
roller blinds. When these blinds are all drawn up, they make
a box with a black interior, the roller blinds being painted black
inside. The top of the well consists of a series of concentric
frames capable of carrying plain and ground glass of various
sizes. When it is necessary to photograph an object against a
black background, it is customary to lay it upon a piece of plain
glass, when the background, which consists of a black hole far
beyond the focus, namely the “interior of the dark-well, gives
an absolutely black background which is obtainable in no other
way. If it is necessary to secure grey backgrounds, a ground
glass is substituted for the plain glass and one of the roller
blinds is lowered and a mirror or other reflecting surface placed
in the box below.

NATURAL SIZE DRAWINGS DIRECT. ~

Another peculiar feature of the illustrator’s ‘room is a piece
of apparatus designed for the production of natural-size or even
reduced drawings with the aid of the camera lucida.

CAMERA LUCIDA FOR NATURAL SIZE OR REDUCED
DRAWING.

Ever since the introduction of the camera lucida, it has been
more or less used for the production of natural size and reduced
drawings; in other words, it was soon seen that its application
went beyond the instrument for which it was primarily designed.
The writer has used the camera lucida to a greater or less extent
in this manner for twenty-five years and has seen plenty of evi-
dence that others have used it in the same way. At one titne it
was thought by certain manufacturers that the demand for an
instrument specially designed for this class of work would justify
the making and advertising of the instruments; but so far as I
am aware, all this apparatus has been now withdrawn from the
market. I do not know what the reason for this course may
have been. It would seem that the instrument met a scientific
need and that its sale should have been sufficient to keep it from
oblivion. The only conclusion one can arrive at is that for
some reason, the form of the instrument did not meet the need.
The fol!owing notes relate to a piece of apparatus which has been
gradually developed during several years, and which has as its
object the application of the ordinary microscope camera lucida
to the purposes we have mentioned. It is a piece of apparatus

Fig. 38. Drawing

to illustrate the use i E

of the ordinary See also
camera riding on a e
vertical system. The Fig. 2
camera lucida frame and 4
is pushed up out of

the way, its details On. the
being, however, here preceding
shown in a some- aes
wnat different manner De eSee
from that illustrated

in Fig. 4. 1,1,1, 1.
vertical girders im- ;
bedded in cement ‘ f iar .

under the building \ \ . : le
and coming up
through the floor
without contact; 2,
right hand box con-
taining a variety of
roller blinds work-
ing in a_ horizontal
direction and so
tinted as to give a
great variety of
transmitted light; 3,
similar right hand
box of roller blinds;
4, 5, 6, roller blinds;
7, drawing board
horizontally and ver-
tically adjustable,
and also tipping to
pass platform 8; 4,
vertically adjustable
platform for the
support of object to
be drawn, in this
case supported on a
microscope stage; 9,
10, clamps for se-
euring 7 and 8 in
position; 11, 11,
screws for clamping
all the previously described apparatus to the steel girders 1, 1,
1, 1; 12. roller blind used as a diaphragm as described in the
description of Fig. 2; 13, diaphragm aperture in the roller blind 12; 14,
lower portion of the framework of the apparatus supporting 2-13; 15, 15, cross-
piece carrying the ordinary camera 17; 16, 16, screw clamps for securing the
eamera after adjustment; 17, ordinary camera; 18, dark-well for securing
black or other background for objects; 19, one of the various adapters for vary-
ing the aperture in the top of the dark well; 20, inner roller blind being used to
secure a light background for the object being photographed; 21, one of the four
roller blinds blackened inside and forming, when pulled up, the black inside surface
of the dark well; 22, 22, vertical slots in which the roller blinds 21, 24, &c., slide
in a light-tight manner; 23, anti-friction bearings of the framework of the ernss-
piece 15; 24, one of the four blinds forming the sides of the dark well.

Se

NIN

DIVISION OF PATHOLOGY AND PHYSIOLOGY
Culture-Room, Main Laboratory

23

which in use is placed in front of a window, in fact is usuaily at-
tached either to the window, the window casing, or to special
uprights near by. As exemplified in this laboratory, the appara-
tus is attached to two upright girders, the same two that carry
the ordinary photographic camera. Both these attachments are
slung on sash weights and can be moved ‘up and down, so thiat
either may be brought into play white the other is raised out
of the way. The camera lucida attachment consists of two dis-
tinct frames which are separated near the middle of the window
by a distance of eight to ten inches. The left hand frame is
designed mainly to support the camera lucida, the right hand
frame to support the drawing board. Both frames carry adjusta-
ble brackets and each bracket carries a horizontal shelf. The
left hand frame therefore has a horizontal shelf carrying the
microscope and this shelf is adjustable in the vertical direction,
and can be clamped in any desired position. In a similar man-
-ner, the right hand frame carries a horizontal shelf, or drawing
board, also adjustable in the vertical direction. The drawing
board presents the peculiarity of being also adjustable in the
horizontal direction, and of rotating about a horizontal axis so
as to pass the opposite shelf,—it is required sometimes above
that shelf and sometimes below it. The size of the apparatus is
determined by that of the human body. The greatest distance
that can be comfortably reached by an ordinary artist for draw-
ing purposes is about thirty inches, i. e., when gazing through
the. camera lucida he can not comfortably produce a drawing
at a distance of more than thirty inches from his eye as the
light travels. An examination of the adjacent illustration will
make this matter somewhat clearer. The camera lucida is
usually carried on a piece of tubing clamped to an ordinary lens
holder or empty microscope barrel. The object to be drawn is
placed below, without a lens, or with a reducing lens, or in some
cases with a lens which slightly enlarges the object. The draw-
ing board is then lowered or raised until the drawing to be made
will have the necessary size. It will be observed therefore that
the whole arrangement is a three-foid one. There is a support
for the object, a support for the camera, and a support for the
drawing board, and these must be adjustable within the limits
of the artist’s reach. It will be seen however that if two of
these are adjustable, the whole system is, for all practical pur-
poses, the same as if all three were adjustable. We now come
to the most important matter in connection with the use of
this apparatus, namely: the illumination of the object and the
illumination of the drawing board. It is possible that it is in
this respect that the apparatus hitherto put on the market fails

24

to meet the requirements of the case. It is very desirable to
fully control the illumination. Sometimes the object has to be
strongly illuminated, and the drawing board weakly illuminated;
sometimes the reverse is the case, the object has to be weakly
‘luminated while the drawing board has to be very strongly
illuminated, and the variation in illumination should be as great
as possible,—from strong sunlight to absolute darkness, if pos-
sible, This is the main point in the successful use of the camera
lucida for this class of work. This object is attained in the
present piece of apparatus by placing the whole at a sunny
window and modifying the light by a series of seven roller blinds,
One of these, and one of the most important, is the blind at-
tached to the window itself. This does not differ from those
elsewhere described in this report. The other blinds for this
piece of apparatus have the peculiarity of working in the hori-
zontal direction, the rollers being placed vertically side by side
and enclosed in a light-tight box at the side of the window. The
box on the right carries three of these rollers and that on the
left carries a corresponding set of three. These blinds are of
varying nature. One of each set is white, another is nearly
translucent and a third is somewhat opaque. By placing these
blinds one over the other, that is by adjusting them properly in
the horizontal direction, the light may be varied to any extent
required. No way has yet been found by which the light both
upon the object and upon the drawing board can be fully con-
trolled by foot-power, as in the case of the microscope window
previously described; but it is believed that if sufficient thought
were given to the subject, such a device might be evolved. In
the meantime, the present arrangement works fairly satisfac- .
torily and avoids the use of complicated apparatus between the
eye and what it is looking at, in the same way as does the appar-
atus previously described in connection with the microscope
window.

A LIBERAL REDUCTION OF ORIGINAL DRAWINGS.

A study of the published work of the best modern artists gives
ample proof that their originals are considerably reduced fot
purposes of publication. From the examination of the published
illustrations it is difficult to give an estimate of the amount
of reduction that takes place in the process of photographing
the original, but a somewhat extensive and careful study of the
best modern magazine illustrations leads to the conclusion that
in many cases the reduction is a liberal one. Judging from the
texture of the drawing as shown in enlarged projections, it is
probably not far from correct to say that the reduction varies

Fig. 4. Sketch

of the arrangement

ot a camera lucida A
for the production
of drawings of ob-
jects at nearly the
natural size. The
apparatus is at-
tached to upright
steel girders, one
at each side of a
window. The artist
faces the light. 1,
2, the two steel gir-
ders which
are imbed-
ded in sev-
eral tons of
cement be-
neath the
building and

Un A
hh I
i il i

24
lt

Wwerreram oe

pass through the floor without contact; 8, cross-piece to carry ‘an or-
dinary camera (4), this cross-piece being hung on sash weights and sliding
in the vertical direction and readily clamped by the side screws shown; 4, ordinary
camera pushed up out of the way but easily brought into use as shown in Fig. 4;
5, anti-friction arms of the cross-piece (3) which roll against the edges of the
girders 1, 2; 6, left hand box of roller blinds; 7, right hand box of roller blinds;
8, light-tight vertically acting rollerblind of the window; 9, 10, horizontally act-
ing roller blinds from the boxes 6, 7: 11, object to be drawn, held in stage forceps;
12, mirror of ordinary camera lucida; 13, horizontal stage. adjustable in the ver-
tical direction, designed to support the object 11, which in this case is supported
on the stage of a microscope carrying no objective or eyepiece; 14, horizontal
stage, adjustable in the vertical direction, designed to support the drawing board,
which tips out to pass 13, and is also adjustable in the horizontal direction. 15, 16,
framework supporting all the apparatus 6-14 and slung on sash weights so as to
be easily pushed up out of the way when the window is used for other purposes;
17, screw clamp to stage 14; 18, roller blind acting as a light trap and diaphragm
when the window is used with the solar »rojector as shown in Fig. 2.

PI2 4 yusuIpsadx_ sy} Jo uos}30q
ADONOISAHA ANY ADONTOHIVd AO NOISIAIA

VL ALL

THULE TAAL

27

from one-~haif to two to three times, i. e., the areas of the pub-
lished illustrations are from one-fourth to one-ninth that of the
original drawings.

lt seems doubtful whether artists ‘have yet fully appreciated
the advance that has been made in the art of etching on metal,
and also doubtful whether we are not laboring too much
under the influence of the former styles of reproduction.
Without intending any disparagement to the high class illus-
tration work of the past, I venture to call. attention to the
probable gain to be obtained by taking greater. advantage
of the perfection of modern etching processes. The best
etchers, supplemented by the best printers, are now able
to produce on good book paper well-defined lines as narrow
as one four-hundredth of an inch. This is far beyond the
power of any artist’s pen if the work he does is to come within
commercial limits. While what is here said refers more particu-
larly to scientific illustrations, it is believed it is not without its
application throughout the range of black and white line work
subject to reproduction by means of photography and etching.
Speaking from the scientific point of view, many of the i'lustra-
tions required are of objects far beyond the reach of unaided
vision, to say nothing of the capacity of the artist, and we always
resort to magnification in order to avoid this difficulty. ‘Natural
size illustrations are the best; reductions and enlargements are
resorted to as.a compromise with our methods of reproduction
and publication. Any hint that will lead us to bring our illustra-
tions nearer the truth and more nearly to the natural size should,
therefore, be of value. Now, it is found that if original drawings
are made on a large scale by means of various mechanical meth-
ods, some of which are described in the course of these pages,
justness of proportion and accuracy in the formation of the lines
are much increased. By taking advantage-of high class modern
etching it is possible to reduce these large original drawings
and retain in the resulting comparatively small and therefore
also comparatively inexpensive illustrations, all that justness of
proportion and accuracy of line that is displayed in the large
original. So far as the writer has exploited the matter, he be-
lieves that reductions to one-tenth and even one-twentieth linear
are feasible, i. e., the blocks for publication will have only 1-100th
to 1-400th the area of the original drawing.

What has hitherto been said introduces no practical difficulty.
The modern mechanical processes will meet all the requirements
that have been mentioned. There is however a rather serious
difficulty connected with producing the original drawings. It is
very difficult for an artist who has formed a style that meets the
needs of former requirements to so alter it as to meet the exi-

28

gencies of the liberal reductions that have just been mentioned.
I find that the tendency of all artists. who have been engaged
upon my work is to do more work on these coarse originals, if
I may so style them, than is necessary. The tendency is to
make the work too fine, to do too much, the result being that
the limits of the etcher are passed in certain respects, particu-
larly in the narrowness of the white lines, so that the problem
confronting the artist who attempts to work in the manner indi-
cated is to learn a coarser style of work and to learn how much
he can leave out. Once this art has been acquired, the rest is
clear sailing and the gain in the published illustration may be
briefly summarized by saying that it is nearer the natural size,
i. e., the ideal size; second, its lines are brought nearer the limit
of modern processes, in other words, are finer where it is neces-
sary that they should be finer; of course nothing is here for a
moment urged against the use of coarse lines wherever they are
appropriate; thirdly, the drawing gains in the important point
of scientific accuracy; fourthly, there is a greater range in width
of line; fifthly, the great reduction gives the photographer less
trouble and at the same time lines accidentally gray are better
rendered.
EXPERIMENT FIELD.

At the Experiment Field a number of experiments have been
started, having for their primary object a physiological and path-
ological study of the cuttings of cane and their germination.

These experiments are of a preliminary nature, and it is not
expected that many of them will do more than point out the
best method of procedure for next year. The plantings were
unavoidably late, and many of the conditions surrounding the
experiments were such as to preclude anything more than mak-
ing a beginning this present year; but it may be well to outline
some of the objects of the different experiments,

The extent to which cane cuttings may be injured by lengthy
soaking in Bordeaux mixture, has been tested in a preliminary
way. The strength of Bordeaux that cane cuttings will bear has
been the subject of another small experiment. The relative
germination of cuttings showing a definite number of diseased
fibres has been tested in another small experiment. Cuttings
have been prepared in different ways with the object of ascer-
taining whence the bud derives the greater portion of what may
be called its internal nourishment. The effect of lime on cane
cuttings has also been the subject of experiment. A number of
other experiments are in progress, and a plan of work for next
season is being most carefully elaborated. It is thought that a
careful study of the whole subject of the early history of the

planted cuttings will yield results that may prove of considerable
importance, ‘

29

Plan of the Experiment Field of the Division of Pathology and Physi-
ology, drawn to scale. The trees have been drawn to scale to show the original
condition of the field as nearly as possible. The right hand half of the field
carried a heavier growth of trees than the other half, and moreover horses were
formerly in the habit of camping under the trees of this part of the original field,

as the trees there afforded better shade in the daytime. These facts rendered

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this part of the field less suitable for experiments. Accordingly the first year’s
planting has been confined to the other and less objectionable portion. This course
leaves the experiments as little as possible under the uneven influence of these
former factors, and gives the best conditions possible under the circumstances.
Land newly cleared and newly cultivated nearly always presents these unevenesses,
and on that account, unless fallowed for a sufficient length of time, is more
unsuited for many classes of experiment work.

The plan is lettered and fully explains itself.