of the plant, was drawn with a brush charged with white ink upon a
black ground. In the simplest possible way relief has been obtained by
representing the leaflets of the nearer fronds by white spaces, whilst
those further away are represented by white outlines. An enlargement
of a frond is shewn on the lower part of the picture, and here the
parts are represented in black on a white ground. The leaflets are in
black outline and the fruits are made to stand out, as in the upper
part, by the use of local colour--in this instance black--their shape
being indicated by the curve of the higher lights. In brief, a very
effective drawing has been made by the simplest use of the white line,
the white space, the black line and the black space.
[Illustration: Fig. 17. _Fucus volubilis_, var. _Flexuosus_, a
seaweed.
(From a drawing by Miss Baker.)]
This may be compared with figure 17, which was drawn by Miss Baker;
the method pursued is entirely different to the last, it being a pure
pen and ink drawing on white paper. No local colour has been employed,
and the modelling has been expressed by the lines used for shading
which have been made by short strokes with a fine pen. The result
is suggestive of an engraving but this was not intentional; under no
circumstances should an attempt be made to imitate in a relief block
effects which can only be obtained by intaglio.
From what has been said it is obvious that the photo-mechanical line
block can be used for the reproduction of all kinds of drawings in
pure black and white; to illustrate this figures 18-26 have been
inserted.
[Illustration: Fig. 18. The Larkspur (_Delphinium ajacis_). By R. G.
Hatton. (Hatton, _Craftsman's Handbook_.)]
[Illustration: Fig. 19. Hollyhock (_Althaea rosea_). By R. G. Hatton.
(Hatton, _Craftsman's Handbook_.)]
[Illustration: Fig. 20. A Liverwort (_Lepidozia reptans_). (Evans,
_Annals of Botany_, 1912, vol. 26.)]
[Illustration: Fig. 21. A Seedling of _Bruguiera gymnorhiza_, a
mangrove. Drawn by Mrs. F. E. Fritsch. (Tansley and Fritsch, _New
Phytologist_, 1905, vol. 4.)]
[Illustration: Fig. 22
A diagrammatic sketch by Mrs. F. E. Fritsch of _Rhizophora conjugata_,
a mangrove. (Tansley and Fritsch, _New Phytologist_, 1905, vol. 4.)]
[Illustration: Fig. 23
A shoot of _Acanthus ilicifolia_, a mangrove. Drawn by Mrs. F. E.
Fritsch. (Tansley and Fritsch, _New Phytologist_, 1905, vol. 4.)]
[Illustration: Fig. 24
A longitudinal section of a fossil seed, _Conostoma oblongum_. Drawn
by Dr. E. J. Salisbury. (Oliver and Salisbury, _Annals of Botany_,
1911, vol. 25.)]
[Illustration: Fig. 25
The Meadowsweet (_Spiraea ulmaria_), shewing four years' growth.
(Yapp, _Annals of Botany_, 1912, vol. 26.).]
[Illustration: Fig. 26. The Chesil Bank. (Oliver, _New Phytologist_,
1912, vol. 11.)]
THE DRAWING OF MICROSCOPIC DETAILS.
Questions relating to the drawing of microscope sections may now be
dealt with. Usually these are drawn in pencil and reproduced by means
of lithography; this is quite wrong, for in addition to its being an
unnecessary expense, it is also an inconvenience to a reader, since
the figures are necessarily divorced from the letterpress. There are
very few histological details which cannot be represented by line
blocks, and with a proper co-operation between the author, the
block maker, the printer and the publisher, even the delicacies of
karyokinesis could be reproduced in the text.
For demonstration purposes, transverse sections of plant-structures
may first be taken.
The walls of the various elements may be represented by lines of
more or less equal breadth, but in those cases where the walls are
particularly thick, _e.g._, the elements of the wood, the thickening
may be represented by an additional line. This is seen in Fig. 27, in
which it will be noticed that the middle lamellae of the wood-elements
are represented by black lines.
[Illustration: Fig. 27.
(From Butler's paper on Gummosis of _Prunus_ and _Citrus_. _Annals of
Botany_, 1911, Vol. 25).]
This is a particularly good drawing, but, unfortunately, it has been
over reduced.
On the other hand, the various tissues may be represented by lines
of varying breadths, the thickest walled cells having the same double
contour as in the above, but with the addition of local colour in
the shape of diagonal shading. This is not uncommonly found in
papers dealing with the anatomy of plants by French authors; it is
illustrated in Figure 28 _a_. If preferred, such thick-walled elements
may be entirely represented by thick black lines as in Figure 28_b_,
and when such cells are relatively few in number, this method has much
to recommend it since a greater relief is obtained.
[Illustration: Fig. 28
_a_
_b_
_c_
A transverse section to shew the vascular cylinder of the root of the
spinach, _c_ is somewhat older than _a_ and _b_.]
Finally, an attempt may be made to draw in a more detailed fashion
as in Figure 28_c_. Here the thickness of the cells of the wood is
represented by broad black lines, the middle lamellae being left white.
The lines marking the boundaries of the other cells vary slightly in
thickness, but this is to a great extent masked by the representation
of the cell contents, which consist entirely of dots in the case of
the protoplasm, whilst the nuclei are represented by dark ovals--black
relieved with small white areas. By varying the size of the dots and
their distance apart, varying densities can be indicated.
It has been mentioned above that it is possible to reproduce fine
detail by means of the line block; this is illustrated in Figs. 29 and
30.
[Illustration: Fig. 29]
Fig. 29, which illustrates a stage in the division of a nucleus,
was drawn with black crayon on a rough-grained piece of Whatman's
water-colour paper. The cytologist will, doubtless, criticize its
coarseness, but it may be mentioned that the roughest paper at hand
was designedly employed in order to illustrate the point raised. That
a finer grained paper will give more delicate results is shewn by Fig.
30, which is a reproduction of a drawing, kindly lent by Dr. W. G.
Ridewood, made with ordinary lead pencil on grained Bristol board. Its
delicacy is obvious, and at first sight it could easily be mistaken
for a lithograph.[A]
[Footnote A: Many similar examples will be found in Ridewood's
memoir _On the Cranial Osteology of the Clupeoid Fishes_,
Proc. Zoo. Soc., Lond., 1904, vol. 11, p. 448.]
[Illustration: Fig. 30]
A half-tone can be put on to a line block during its manufacture. All
that the draughtsman has to do, is to indicate by blue pencil lines
those parts on which he requires the dots, which give the half-tone,
to be placed, and to select the pattern of the stipple he desires to
be used. The result may appear somewhat mechanical since the dots
are regularly arranged, but a drawing sometimes may be considerably
improved by this means if used with judgment. It is frequently
employed in representing drapery, and many examples may be found on
those pages of newspapers devoted to ladies' dress (Fig. 31; see also
Fig. 32).
[Illustration: Fig. 31. After a water-colour design by Miss Winifred
Pearse.]
THE DRAWING OF DIAGRAMS AND APPARATUS. Much valuable information may
be conveyed by diagrams; in fact, these could be used more freely than
they are.
[Illustration: Fig. 32]
The principles to be borne in mind are the same as for other ink
drawings. They should always be drawn upon an enlarged scale, and with
as little detail as possible, which generally should be indicated
in the most conventional ways--dots, black spaces, lines, and so on
(Figures 33 and 34). The main thing to be aimed at is clearness, so
that it is often necessary to sacrifice true relative proportions in
order to gain this end (Fig. 34).
[Illustration: Fig. 33. A diagram by Mr. E. Lee. (_Annals of Botany_,
1911, vol. 25.)]
[Illustration: Fig. 34
A Diagram from the _Annals of Botany_, 1912, Vol. 26.]
In certain cases it is possible to combine detail and diagram in one
drawing; this is shewn in Fig. 32, taken from Dr. Ridewood's admirably
illustrated memoir on the _Gills of Lamellibranchiata_ (Transactions
of the Royal Society of London, B. vol. 195, 1903). The shading
employed was either done by the draughtsman (at _ch_ and in the cells
with irregularly arranged dots), or else was put on the block during
its manufacture (_af_). If a lens be used, the difference will at once
be obvious.
The finished drawing should be bold and neat, and all lettering should
be very clear. If several figures are included in one diagram they may
be separated one from the other by ruled lines, and in no case should
one tier of figures--taking the frames as the boundaries--unevenly
overlap another tier, otherwise the diagram, to use an expressive
phrase, will look "like a pig with one ear."
Under the heading of diagrams must be included the representation of
apparatus. There are two ways of drawing apparatus; the objects may
be drawn as a study in still life, as, for example, in many of the
figures illustrating Deschanel's _Natural Philosophy_ (London, 1890)
or they may be represented in a purely conventional fashion. The
latter is the better way, and it is preferable to draw for the most
part in section in order that all connections, inlets, outlets, etc.,
may be clearly shewn.
A study of a good example is infinitely better than a written
description, wherefore Figure 35 has been inserted.
[Illustration: Fig. 35]
It will be observed that all glass vessels and tubing are represented
in section, and in the thermometers, the fine capillary bores are
represented by a single line in each case; corks by diagonal shading;
wood by lines in imitation of its grain; metal parts by vertical
shading or dead black; more or less still liquids by a series of lines
broken below and continuous at the surface, and gradually becoming
closer and closer together towards the surface. Mercury, on the other
hand, may be indicated by dead black relieved by a few white lines to
represent its reflecting surface, also its free surface may be drawn
convex. Finally thumb screws may be shewn by a combination of black
areas and vertical shading.
These conventionalities need not all be followed; for instance, rubber
connexions may be indicated by broad black lines and wood by diagonal
shading.
The drawing should be very bold and the different parts clearly and
freely indicated by writing or "printing."
THE DRAWING OF MAPS. In the drawing of maps for reproduction by the
line block process, if an existing map serves the purpose, a tracing
may be made in ink on translucent linen. If, on the other hand, the
author has to make his own map, the problem becomes more difficult.
For the obtaining of the data for map making information must be
sought for elsewhere, since we are only concerned in the preparation
of the map for publication. And as regards this, but few general rules
can be laid down since the character of maps is so diverse.
The amount of detail in the physical features represented depends to
a great extent upon the scale. Thus streams of a greater breadth than,
say, 10 feet, may in large scale maps be represented by double lines,
whilst no stream less than 2 feet in breadth will be shewn in low
scale maps.
[Illustration: Fig. 36
_a_ Contoured.
_b_ Spot-levels.
_c_ Layered.
These three figures illustrate in three different ways the varying
levels of a piece of ground surveyed by Prof. F. W. Oliver and Mr. A.
G. Tansley.]
The indication of hills is always a problem; the most satisfactory
way is by the drawing of contours (Figure 36_a_), and this whenever
possible should be followed, since it is scientifically the most
correct method, inasmuch as when properly drawn the form of the hill
is shewn exactly; further, contours obscure the detail to a much less
extent than does shading, and but little artistic talent is required
to draw them. If, however, contouring be impossible, the various
heights above the datum may be shewn by spot levels (Figure 36_b_)
or the relative levels may be shewn by layers; that is to say, by a
system of shading each kind of which indicates a certain level. Thus
dots may be used for all parts not more than 100 feet above sea level,
vertical lines for regions between 100 and 200 feet, horizontal lines
for parts between 200 and 300 feet, and so on (Figure 36_c_). It is
obvious that this method cannot be pursued if vegetation also is to be
shewn. The last choice is to represent the hill by shading in much the
same way as many of us did when children; the method referred to was
known as "herring bones" or "hairy caterpillars."
The sea or a broad expanse of water may be indicated by fine lines
which follow the coast-line and which may be placed at gradually
increasing distances apart.
If geological strata are to be represented, the accepted symbols
should be used; if the map is intended to represent the distribution
of soils, convenient signs may be employed, _e.g._, large dots for
shingle or gravels, small dots for sand, black areas for clay, and
so on; finally, if the distribution of plants or of animals is to be
shewn, symbols again may be employed. These, however, must be
quite simple and as far as possible give an idea of the organism
represented. This, in the case of animals, may be a difficulty, but,
with regard to plants, simple signs are easily inserted which give a
very good idea of the plant it is intended to represent. Many of the
signs used by the Ordnance Survey are ready to hand, and these can
often be used to designate plant associations.
The delimitation of areas should always be clearly shewn, and all
names should be very clearly "printed" indeed, and if they must be
placed on a dark portion of the map, they should have a good white
border around them.
The north should always be indicated. This may be done by drawing in
its proper position a representation of a compass or merely an arrow
pointing to the north. Unless otherwise stated, the arrow is assumed
to point to the magnetic north, and if no north be actually shewn it
is taken for granted by an intelligent reader that one of the vertical
sides is a true north and south line, with the north at the top.
Finally, under no circumstances should a scale be omitted--it is the
first thing a reader should look for.
For a map to look well two things are all-important, neatness and
clearness; both of these may nearly always be secured by drawing on
a large scale, bearing in mind what has been said about crowding
the detail, etc., and carefully considering how much reduction the
original can stand. This last point is of vital importance, for an
over-reduced map is an abomination; we have seen really good maps
absolutely ruined by this stupid error.
The inexperienced author should study the methods pursued by Prof.
Yapp in Figure 37. For comparison, the simpler way adopted by Mr.
Wilson may be studied (_Annals of Botany_, 1911, Vol. 25).
[Illustration: Figure 37. A Map of the Fenland by Prof. Yapp. (_New
Phytologist_, 1908, Vol. 7)]
GRAPHS OR CURVES. Simple though it be, the plotting of a curve for
reproduction requires thought and care. In the first instance, the
curve is drawn on squared paper, and the question naturally arises--To
what extent are the squares to be represented? If it be desired to
reproduce all the lines, say the paper is ruled in millimetres, a
half-tone may be employed, or all these lines can be ruled over in
black ink where the reproduction by line block is possible. It is,
however, seldom necessary to represent all the smallest squares; it
will generally be found that the centimetre squares are sufficient. If
the original be plotted on paper which is ruled in pale blue, it can
be reproduced by line block without re-drawing, since the blue will
photograph as white with the plates commonly used; all the essential
lines and curves must, of course, be in black. If, however, the
rulings of the squared paper are in red, yellow, or dark blue, a
tracing must be made. The horizontal and vertical sides should be
ruled with a broad black line, but the internal intersecting lines
should be much thinner. The actual curve may be in a continuous line
if one only be shewn on the graph; if more are drawn, then each must
be different, the obvious variations being the thick continuous line
---- the thin continuous line ----, dashes either thick or thin
---- ---- ----, dots . . . . . , and finally combinations of dots and
dashes ---- . ---- . ---- .
Owing to the difficulty which some experience in drawing freehand a
continuous line, the plot should be made twice the linear size of the
intended reproduction. A good rule to follow in drawing lines is to
keep the eye fixed on the point where the line is to end, the hand
will then guide the pen in the right path, especially after a little
practice. In many cases the ruler may be used, not only for straight
but also for curved lines, for good curve rules may be purchased.
In order that the figure may look neat, the lines should be of an
even thickness throughout their length; this is easily accomplished by
means of a ruling pen.
It has been stated above that Bristol board is the best material to
use for the making of drawings for line blocks; other materials may,
however, be employed, although they are not so nice to work upon.
For instance, it may be necessary to reproduce a map; this, as has
already been mentioned, may be conveniently done by pinning over the
map a sheet of pale blue tracing linen, and tracing the map on this
with Indian ink. The fact that the linen is blue does not matter, for
it will photograph as if it were white.
Then again, many subjects may be of so complicated a nature as to be
beyond the skill of the author to draw. In such a case a good plan
is to take a photograph of the object and make a positive on smooth
bromide paper, which need only be developed sufficiently far to give a
print which just shows the features. The print, when dry, can then be
worked on with fixed Indian ink. The finished drawing, when quite dry,
may be immersed in any solution which will dissolve out the silver; a
solution of iodine in potassium iodide answers sufficiently well. The
print will turn very dark, but it must be allowed to remain in the
bath until all the silver has dissolved; it is then removed, rinsed
under the tap and placed in an ordinary fixing bath of hyposulphite
of soda. All the colouration will be quickly removed so that the ink
drawing will stand out well against the white paper. All that it now
requires is a thorough washing in water; when dry it may be touched up
and then placed under pressure in order to make it quite flat.[A]
[Footnote A: The chief disadvantage of iodine solution is its
slowness of action; the following methods are much quicker.
(_a_) To a solution of 4 oz. of hyposulphite of soda in
one pint of water, add a 10 per cent. aqueous solution of
potassium ferricyanide until the mixture is lemon coloured.
When the silver image has quite disappeared, wash the print
thoroughly in water. Since the mixture does not keep, the
ferricyanide solution should be added to the hyposulphite
solution immediately before use.
(_b_) Mix 125 ccs. of a 10 per cent. alcoholic solution of
iodine with 21 ccs. of a 10 per cent. aqueous solution of
potassium cyanide, add to the mixture 1 litre of water.
When the image has disappeared, which will be in less than a
minute, wash for five minutes in water and dry.]
This method of drawing over photographic prints will often save
a considerable amount of time. For instance, it may be desired
to reproduce a consecutive series of drawings to illustrate the
microscopic structure of the subject. The ordinary way of doing this
is to make camera lucida drawings of the sections, which is a lengthy
and tiresome process; a photograph of each section will take much less
time and will give quite as good results.
Before sending any line drawings to press they should be carefully
examined; pencil marks may be rubbed out, lines touched up,
unnecessary lines removed by painting them out with white or black ink
according to the background, and, finally, a frame ruled around, if
necessary.
The amount of reduction, which should be marked clearly on the margin,
requires very careful consideration since under reduction may cause
the reproduction to appear too coarse whilst over-reduction may result
in the loss of the finer detail and the drawing may, moreover, appear
spiritless.
It must also be remembered that a reduction of, say, 1/2 linear means
that the reproduction will be a quarter the area of the original.
The best way to indicate the reduction required is to draw a vertical
or horizontal line, parallel to a side or the base of the picture,
of the exact length; or, the line may be roughly drawn and its length
indicated by figures thus ------------2-1/2"--------- .
The question arises as to when line drawings for reproduction by the
zinc block should be employed.
The answer is, Whenever possible.
The advantages to a reader of having the illustrations in the text
has already been commented upon. It is about the only method commonly
employed in which practically everything depends on the draughtsman;
the author thus exercises the greatest control. Finally the fact that
it is very inexpensive will appeal to editors and publishers.
As a matter of curiosity, the present writer picked out at random a
recent volume of a scientific journal to examine the illustrations;
although there were a number of text figures, an examination of the
plates--chiefly lithographs and collotypes--showed that there were a
large number of figures which ought to have been in the text. A more
detailed inspection of the plates was therefore made, with the result
that nearly 200 figures were found which with the minimum amount of
alteration--merely drawing in ink instead of pencil in the majority of
cases, and leaving out unnecessary shading in the others--could have
been reproduced by line blocks. If this had been done, a saving of
over 20 per cent. could have been effected on the plates. Some of this
would, of course, have been absorbed in the making of zincos, but
not much, since line blocks of excellent quality can be obtained for
2-1/2d. and 3d. per square inch. The above relates only to the most
obvious examples; the saving in plates would have been enormous if the
authors had drawn for the line process.