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G. (Thomas George) Hill + +This eBook is for the use of anyone anywhere at no cost and with +almost no restrictions whatsoever. You may copy it, give it away or +re-use it under the terms of the Project Gutenberg License included +with this eBook or online at www.gutenberg.org + + +Title: The Essentials of Illustration + A Practical Guide to the Reproduction of Drawings & + Photographs for the Use of Scientists & Others + +Author: T. G. (Thomas George) Hill + +Release Date: January 7, 2011 [EBook #34869] + +Language: English + +Character set encoding: ISO-8859-1 + +*** START OF THIS PROJECT GUTENBERG EBOOK THE ESSENTIALS OF ILLUSTRATION *** + + + + +Produced by Lesley Halamek, Chris Curnow and the Online +Distributed Proofreading Team at https://www.pgdp.net (This +file was produced from images generously made available +by The Internet Archive) + + + + + + +</pre> + + + <h1 style="margin-top: 3em;">THE ESSENTIALS OF ILLUSTRATION</h1> + +<h2 style="margin-top: 2em;">A PRACTICAL GUIDE TO THE REPRODUCTION OF DRAWINGS<br /> & +PHOTOGRAPHS FOR THE USE OF SCIENTISTS & OTHERS</h2> + +<h4 style="margin-top: 3em;">By</h4><br /> +<h2 style="margin-top: -1em;">T. G. HILL</h2> + +<h4>Reader in Vegetable Physiology in the University<br /> + of London, University College</h4> + +<h4 style="margin-top: 8em;">LONDON<br /> + WILLIAM WESLEY & SON<br /> + 28 Essex Street, Strand<br /> + 1915</h4> + +<h5 style="margin-top: 3em; margin-bottom: 6em;">PRINTED BY THE WESTMINSTER PRESS, LONDON, W.</h5> + +<span class="pagenum"><a name="pagev" id="pagev"></a>page v</span> + +<h3>CONTENTS</h3> + +<table summary="ToC" align="center" width="auto" border="0" style="margin-bottom: 5em;"> + <tr> + <td> </td> + <td class="right1">PAGE</td> + </tr> +<tr> + <td class="left"><span class="sc">Intaglio Printing</span></td> + <td class="right"><a href="#page1">1</a></td> +</tr> +<tr> + <td class="left1">Intaglio plates</td> + <td class="right"><a href="#page2">2</a></td> +</tr> +<tr> + <td class="left1">Line engraving </td> + <td class="right"><a href="#page2">2</a></td> +</tr> +<tr> + <td class="left1">Etching</td> + <td class="right"><a href="#page5">5</a></td> +</tr> +<tr> + <td class="left1">Soft-ground etching</td> + <td class="right"><a href="#page6">6</a></td> +</tr> +<tr> + <td class="left1">Mezzotint</td> + <td class="right"><a href="#page7">7</a></td> +</tr> +<tr> + <td class="left1">Photogravure</td> + <td class="right"><a href="#page8">8</a></td> +</tr> +<tr> + <td class="left"><span class="sc">Plane Surface Printing</span></td> + <td class="right"><a href="#page15">15</a></td> +</tr> +<tr> + <td class="left1">Lithography</td> + <td class="right"><a href="#page15">15</a></td> +</tr> +<tr> + <td class="left1">Chromolithography</td> + <td class="right"><a href="#page20">20</a></td> +</tr> +<tr> + <td class="left1">Photolithographic processes</td> + <td class="right"><a href="#page23">23</a></td> +</tr> +<tr> + <td class="left1">Collotype</td> + <td class="right"><a href="#page23">23</a></td> +</tr> +<tr> + <td class="left1">The preparation of illustrated pages</td> + <td class="right"><a href="#page26">26</a></td> +</tr> +<tr> + <td class="left"><span class="sc">Relief Printing</span></td> + <td class="right"><a href="#page33">33</a></td> +</tr> +<tr> + <td class="left1">Woodcuts and engravings</td> + <td class="right"><a href="#page33">33</a></td> +</tr> +<tr> + <td class="left1">The Half-tone process</td> + <td class="right"><a href="#page37">37</a></td> +</tr> +<tr> + <td class="left1">The Half-tone three-colour process</td> + <td class="right"><a href="#page46">46</a></td> +</tr> +<tr> + <td class="left1">Photomechanical line blocks</td> + <td class="right"><a href="#page49">49</a></td> +</tr> +<tr> + <td class="left1">The drawing of microscopic details</td> + <td class="right"><a href="#page67">67</a></td> +</tr> +<tr> + <td class="left1">The drawing of diagrams and apparatus</td> + <td class="right"><a href="#page72">72</a></td> +</tr> +<tr> + <td class="left1">The drawing of maps</td> + <td class="right"><a href="#page76">76</a></td> +</tr> +<tr> + <td class="left1">The drawing of graphs or curves</td> + <td class="right"><a href="#page79">79</a></td> +</tr> +<tr> + <td class="left1">The swelled gelatine process</td> + <td class="right"><a href="#page84">84</a></td> +</tr> +<tr> + <td class="left">The Relative Cost of blocks and plates by various processes</td> + <td class="right"><a href="#page89">89</a></td> +</tr> +<tr> + <td class="left"><span class="sc">Literature</span></td> + <td class="right"><a href="#page91">91</a></td> +</tr> +</table> + +<span class="pagenum"><a name="pagevi" id="pagevi"></a>page vi</span> + +<h3>ILLUSTRATIONS</h3> + +<h4>1. PLATES</h4> + +<table summary="Illustrations" align="center" width="auto" border="0" style="margin-bottom: 3em;"> +<tr> + <td>PLATE</td> +</tr> +<tr> + <td class="center"><a href="#page14">1</a></td> + <td colspan="3">An original lithograph by Mr. Harry Becker.</td> +</tr> +<tr> + <td class="center"><a href="#plate2">2</a></td> + <td>Chromolithograph.</td> + <td class="right" colspan="2">Messrs. Gerrards, Ltd.</td> +</tr> +<tr> + <td class="center"><a href="#plate3">3</a></td> + <td>Collotype.</td> + <td class="right" colspan="2">Messrs. André, Sleigh & Anglo, Ltd.</td> +</tr> +<tr> + <td class="center"><a href="#page28">4-5</a></td> + <td>Collotype.</td> + <td class="right" colspan="2">Messrs. André, Sleigh & Anglo, Ltd.</td> +</tr> +<tr> + <td class="center"><a href="#plate6">6</a></td> + <td>Half tone.</td> + <td class="right" colspan="2">Swan Electric Engraving Co., Ltd.</td> +</tr> +<tr> + <td class="center"><a href="#plate7">7</a></td> + <td>Half tone.</td> + <td rowspan="6"><img src="images/rightbrace2.png" width="21" height="128" alt="right brace" border="0" /></td> + <td></td> +</tr> +<tr> + <td class="center"><a href="#plate8">8</a></td> + <td>Photogravure.</td> + <td></td> +</tr> +<tr> + <td class="center"><a href="#plate9">9</a></td> + <td>Collotype.</td> + <td class="center">Messrs. André, Sleigh &</td> +</tr> +<tr> + <td class="center"><a href="#plate10">10</a></td> + <td>Half tone.</td> + <td class="center">Anglo, Ltd.</td> +</tr> +<tr> + <td class="center"><a href="#plate11">11</a></td> + <td>Half tone.</td> + <td></td> +</tr> +<tr> + <td class="center"><a href="#plate12">12</a></td> + <td>Half tone three colour.</td> + <td></td> +</tr> +</table> + +<h4>2. TEXT FIGURES</h4> + +<table summary="Illustrations" align="center" width="auto" border="0" style="margin-bottom: 3em;"> +<tr> + <td class="left1">Tailpiece, p. <a href="#page11">11</a>.</td> + <td class="left2">Electrotype from the original wood<br /> + <span class="right">engraving by Bewick.</span></td> +</tr> +<tr> + <td class="left1">Tailpiece, p. <a href="#t30">30</a>.</td> + <td class="left2">Line block. Messrs. Bourne & Co.</td> +</tr> +<tr> + <td class="left1">Fig. <a href="#page32">1</a>.</td> + <td class="left2">Wood engraving.<br /> + <span class="right">Messrs. Edmund Evans, Ltd.</span></td> +</tr> +<tr> + <td class="left1">Fig. <a href="#fig2">2</a>.</td> + <td class="left2">Wood cut. Mr. G. N. Oliver</td> +</tr> +<tr> + <td class="left1">Figs. <a href="#fig3">3</a>-<a href="#fig6">6</a>.</td> + <td class="left2">Line blocks.<br /> + <span class="right">Messrs. André, Sleigh & Anglo, Ltd.</span></td> +</tr> +<tr> + <td class="left1">Figs. <a href="#fig7">7</a> and <a href="#fig8">8</a>.</td> + <td class="left2">Line blocks, reproductions of a wood<br /> + <span class="right">engraving. Mr. C. Butterworth.</span></td> +</tr> +<tr> + <td class="left1">Fig. <a href="#page54">9</a>.</td> + <td class="left2">Line block.</td> +</tr> +<tr> + <td class="left1">Figs. <a href="#fig10">10</a>-<a href="#fig13">13</a>.</td> + <td class="left2">Line blocks, reproductions of wood<br /> + <span class="right">engravings.</span></td> +</tr> +<tr> + <td class="left1">Fig. <a href="#fig14">14</a>.</td> + <td class="left2">Line block.</td> +</tr> +<tr> + <td class="left1">Fig. <a href="#fig15">15</a>.</td> + <td class="left2">Line block.<br /> + <span class="right">Messrs. André, Sleigh & Anglo, Ltd.</span></td> +</tr> +<tr> + <td class="left1">Fig. <a href="#fig16">16</a>.<span class="pagenum"><a name="pagevii" id="pagevii"></a>page vii</span></td> + <td class="left2">Line block.<br /> + <span class="right">Swan Electric Engraving Co., Ltd.</span></td> +</tr> +<tr> + <td class="left1">Fig. <a href="#fig17">17</a>.</td> + <td class="left2">Line block.<br /> + <span class="right">Messrs. André, Sleigh & Anglo, Ltd.</span></td> +</tr> +<tr> + <td class="left1">Figs. <a href="#fig18">18</a>-<a href="#fig20">20</a>.</td> + <td class="left2">Line blocks.</td> +</tr> +<tr> + <td class="left1">Figs. <a href="#fig21">21</a>-<a href="#fig23">23</a>.</td> + <td class="left2">Line blocks. Messrs. Bourne & Co.</td> +</tr> +<tr> + <td class="left1">Figs. <a href="#fig24">24</a> and <a href="#page66">25</a>.</td> + <td class="left2">Line blocks.</td> +</tr> +<tr> + <td class="left1">Fig. <a href="#fig26">26</a>.</td> + <td class="left2">Line block. Messrs. Bourne & Co.</td> +</tr> +<tr> + <td class="left1">Fig. <a href="#fig27">27</a>.</td> + <td class="left2">Line block.</td> +</tr> +<tr> + <td class="left1">Figs. <a href="#fig28">28</a> and <a href="#fig29">29</a>.</td> + <td class="left2">Line blocks.<br /> + <span class="right">Messrs. André, Sleigh & Anglo, Ltd.</span></td> +</tr> +<tr> + <td class="left1">Fig. <a href="#fig30">30</a>.</td> + <td class="left2">Line block. Mr. C. Butterworth.</td> +</tr> +<tr> + <td class="left1">Fig. <a href="#fig31">31</a>.</td> + <td class="left2">Line block.<br /> + <span class="right">Messrs. André, Sleigh & Anglo, Ltd.</span></td> +</tr> +<tr> + <td class="left1">Fig. <a href="#fig32">32</a>.</td> + <td class="left2">Line block. Mr. C. Butterworth.</td> +</tr> +<tr> + <td class="left1">Figs. <a href="#fig33">33</a> and <a href="#fig34">34</a>.</td> + <td class="left2">Line blocks.</td> +</tr> +<tr> + <td class="left1">Figs. <a href="#fig35">35</a> and <a href="#page77">36</a>.</td> + <td class="left2">Line blocks.<br /> + <span class="right">Messrs. André, Sleigh & Anglo, Ltd.</span></td> +</tr> +<tr> + <td class="left1">Fig. <a href="#fig37">37</a>.</td> + <td class="left2">Line block. Messrs. Bourne & Co.</td> +</tr> +<tr> + <td class="left1">Fig. <a href="#fig38">38</a>.</td> + <td class="left2">Lithograph reproduced by the Swelled<br /> + Gelatine Process.<br /> + <span class="right">Artists Illustrators, Ltd.</span></td> +</tr> +<tr> + <td class="left1">Tailpiece, p. <a href="#fig86">86</a>.</td> + <td class="left2">Line block.<br /> + <span class="right">Messrs. André, Sleigh & Anglo, Ltd.</span></td> +</tr> +</table> + +<span class="pagenum"><a name="pageix" id="pageix"></a>page ix</span> + +<h3>PREFACE</h3> + +<p style="line-height: 1%; margin-top: -0.5em;"> </p> +<p class="dropcap"><span class="dcap"> +M</span> +<b>ODERN</b> scientific publications, although they +may in some or even many cases equal in their +scientific quality the memoirs of earlier workers, +do not, on the average, reach a high standard as regards +illustration. For instance, in Great Britain botany is pre-eminent +in its morphological aspects; it should therefore +follow that the illustrations, which form so important a +part of such papers, should be beyond reproach. This is +not always so, a fact which must be patent to anyone +with the slightest critical knowledge who looks through a +typical journal. This is a fact much to be regretted, since +many of the earlier scientists were accomplished draughtsmen +and, indeed, often artists; in this connection the +Hookers and Professor Daniel Oliver may be mentioned. +The implication is not intended that there are no good +amateur draughtsmen nowadays; there are, and in some +cases possessed of great ability. The beautiful work of +Church in his Floral Mechanisms may be cited as an +example.</p> + +<p>It may, of course, be argued that any picture which +serves to illustrate the particular feature is good enough; +this is the contention of one who takes an insufficient pride +in his work. A feature worthy of an illustration deserves +the best the author can produce, more especially as a +literary form is still, fortunately, preserved or, at any +rate, aimed at.</p> + +<p>The reason for indifferent illustrations is primarily +due to bad or mediocre drawings, or to their unsuitability +for the kind of reproduction in view.</p> + +<p>With regard to the first point: this lack of draughtsmanship +often obtains; when education entirely replaces +mere instruction, it is to be hoped that all students of +<span class="pagenum"><a name="pagex" id="pagex"></a>page x</span> +science will be trained in the rudiments of drawing. +Meanwhile the difficulty can be partly overcome, as will +be seen later on, by the simple means of drawing on an +enlarged scale, in order that in reproduction reduction +can be made.</p> + +<p>The second reason, the onus of which also falls on the +authors, is a lack of knowledge regarding the kind of +drawing suitable for the different modes of reproduction; +this is a very important point, for "technical conditions +govern even genius itself."</p> + +<p>Authors, however, are not always to blame; it would +appear that even editors sometimes are wanting in the +requisite knowledge, for we have known straightforward +line drawings reproduced by half-tone; in other cases the +paper used is unsuitable for the reproduction and, at +other times, the printers are at fault.</p> + +<p>With a view to remedying, at any rate in part, these +deficiencies, a course of lectures, arranged by the Board +of Studies in Botany of the University of London, was +delivered in the Lent term of 1913 in the Department of +Botany of University College, London.</p> + +<p>In gratifying the wish expressed by some that these +lectures should be given a more permanent dress, the +author feels that some apology is necessary, for he can +lay no claim to authoritative knowledge of much of the +subject-matter; questions relating to the graphic arts +and to illustrations, however, have always been of interest +to him, so that he has tried various experiments, often +with disastrous results, and thus has gained some +experience.</p> + +<p>In these matters the author has benefited much +through his association with Professor F. W. Oliver, +who, characteristically, has been ever ready to discuss +these problems with, and to place his knowledge and +experience at the disposal of the author.</p> + +<p>The outline of the ways and means of illustration +<span class="pagenum"><a name="pagexi" id="pagexi"></a>page xi</span> +contained in the following pages is primarily intended +for ordinary working scientists, not for artists, professional +draughtsmen or skilled amateurs.</p> + +<p>The point of view is mainly botanical, primarily +because the present writer is a botanist and also because +the requirements of modern botany in the way of illustrations +are more extensive than those of any other +science; the requirements of other sciences, however, +have not been overlooked. With regard to other branches +of knowledge, the principles considered will, it is hoped, +prove of some value to the workers therein.</p> + +<p>The details of technique have been kept as brief as +possible; in fact, sufficient only has been said to indicate +the main principles involved. In the literature cited, to +which the author is indebted particularly for matters +relating to technique, will be found full, and sometimes +exhaustive, accounts.</p> + +<p>With regard to the illustrations, these have been +selected to illustrate the various methods of reproduction +described or to demonstrate the points raised. In those +instances where the source has not been acknowledged +or the draughtsman or photographer mentioned by name, +the figure is by the author: and since the actual making +of plates and blocks is of considerable importance, the +firms, when known, responsible for their making are +mentioned in the Table of Illustrations. In this connexion +the author desires to express his appreciation of +the skill shewn and care taken by Messrs. André, Sleigh +and Anglo, Limited, who prepared the majority of the +new illustrations which appear in the following pages.</p> + +<p>The author is indebted to many who have helped in +various ways in the production of his work; particularly +is he desirous of expressing his warmest thanks to Miss +O. Johnston for the charming drawing of <i>Geranium +columbinum</i> (Plate 2) and to Mr. Harry Becker for his +beautiful lithograph (Plate 1). To Miss S. M. Baker, +<span class="pagenum"><a name="pagexii" id="pagexii"></a>page xii</span> +Dr. W. G. Ridewood, and Miss Winifred Smith thanks +are due for the loan of original drawings; also to Mr. +Edward Hunter and Mr. Hugh Hunter for information +regarding matters of technique and cost.</p> + +<p>The number of illustrations would have been less but +for the generosity of Messrs. Chapman and Hall, the +Editors of the "Annals of Botany," "The Imprint," +and the "New Phytologist," Professor F. W. Oliver +and Mr. G. N. Oliver in lending blocks. Recognition +also must be made of the kindness of Mr. Richard G. +Hatton in consenting to the use of certain blocks from +his admirable "Craftsman's Handbook," of the Delegates +of the Clarendon Press for permission to reproduce +figure 14, and of Messrs. Frederick Warne and Co. for +permission to make use of the wood engraving by +Messrs. Edmund Evans, Ltd., of Kate Greenaway's +charming Milkmaid. Finally, the author desires to +express his sincerest thanks to Mr. Gerard T. Meynell, +of The Westminster Press, for the keen interest he has +taken in the work, for his help with the illustrations, +and for the great care he has taken in the production of +the book.</p> + +<div class="poem"> <div class="stanza"> +<p>University College, London</p> +<p class="i4"><i>January, 1915.</i></p> + </div> </div> + +<span class="pagenum"><a name="page1" id="page1"></a>page 1</span> + +<h2 style="margin-top: 3em;">INTAGLIO PRINTING</h2> + +<p style="line-height: 1%; margin-top: -0.5em;"> </p> +<p class="dropcap"><span class="dcap"> +I</span> +<b>N</b> the biological sciences the massing of illustrations +into plates is still the favourite method of illustration, +although text-figures have recently become more +numerous.</p> + +<p>This is partly due to innate conservatism, for most of +the earlier memoirs were so illustrated, doubtless because +it saved time, since if wood engravings were used with a +view to text-figures, the compositor had to wait for the +blocks, whereas in the case of plates the compositor and +the engraver worked independently. Also the possibilities +of plates are enormous; they may be very beautiful +indeed besides being biologically satisfactory, for much +finer results can be obtained by engraving metal than +by engraving wood. Then again there are many different +processes available for the making of plates, so that if +one proves unsuitable for a subject an excellent reproduction +may be obtained by another.</p> + +<p>Before passing on it is desirable to point out the +essential differences in the three ways of printing.</p> + +<p><i>Intaglio printing.</i> If the finger-tips be examined, many +ridges and furrows will be seen on their under surfaces; +if now a thick ink be well rubbed into these so as to fill +well the furrows, and the superfluous ink be wiped off +from the general surface, an impression will be obtained +of the furrows on pressing the fingers on to a piece of +smooth white paper. Better still, if the copper plate of a +visiting card be examined, the name will be found +cut into the surface. If an intimate mixture of tallow +and lamp-black be well rubbed into these depressions +and the excess of ink wiped off the surface of the plate, +an impression can be obtained by placing a piece of damp +<span class="pagenum"><a name="page2" id="page2"></a>page 2</span> +paper on the plate and passing both through the domestic +mangle—the kind with rubber-covered rollers. In each +case the principle is the same, the pressure forces the +paper into the depressions of the plate so that it takes +up the ink.</p> + +<p><i>Plane surface printing.</i> This is characteristic of lithography +and allied processes. Writing or a design well +chalked on a blackboard can be transferred on to a smooth +piece of paper merely by a little vigorous rubbing on the +back of the paper placed in position over the drawing. +The transfers of childhood provide a further simple +illustration, so also does the hectograph (jellygraph).</p> + +<p><i>Relief printing.</i> In this case, the design is raised above +the general surface of the substance. A rubber stamp is +an obvious example.</p> + +<p>It will be noticed that intaglio and relief are the reverse +one of the other, whilst plane-surface printing is intermediate +between these extremes. In intaglio, the ink is +taken from a depression; in relief from an elevation; +and in flat printing from a plane surface.</p> + +<p><span style="font-size: 1.2em"><b>INTAGLIO PLATES.</b></span> There are several methods +of making intaglio plates, but only a few are used in +the illustration of scientific papers; attention however +may be drawn to the others, not only for their own sake, +but also on account of their influence on some modern +photo-mechanical processes.</p> + +<p><span style="font-size: 1.2em"><b>LINE-ENGRAVING.</b></span> Line engraving, by which is +meant cutting lines into copper, steel, or other suitable +material with a burin or graver, is a very ancient art. +Its employment for illustrative purposes is an outcome +of the art of the metal workers—particularly the +Florentine goldsmiths of the fifteenth century—who filled +up the lines cut in the metal with a black enamel of silver +and lead sulphides (niello) which was made by heating +<span class="pagenum"><a name="page3" id="page3"></a>page 3</span> +together a mixture of these metals with sulphur. This +enamel when once in was very hard to remove, so that +in order to see how their lines were progressing, the +artists rubbed well into the metal, in order to fill up the +lines, a sticky ink. The superfluous ink was then wiped +off the general surface of the metal and a piece of paper +was placed in position and pressed sufficiently hard to +make it enter the depressions, which alone contained the +pigment, and take up the ink. A print was thus obtained +of the work and so its state was ascertained.</p> + +<p>Metal engraving is carried out in the same fashion +at the present time. A flat plate of copper or steel is well +polished and is worked upon with a graver or burin, so +that the picture is represented by lines cut into the metal. +Any line, however fine, will give an impression on printing, +hence it is hardly surprising that engraving has long +been a popular means of expression by artists, since force, +depth and delicacy are possible of attainment.</p> + +<p>The printing is carried out in exactly the same way as +by the early metal workers: the plate is covered with a +thick ink which is forced well into the lines and then the +superfluous ink is removed. The plate is now ready for +printing; to do this, the plate is placed in the bed of a +copper-plate press and over it is laid a sheet of damped +paper which is covered with two or three layers of blanket. +The whole is then passed under the roller which forces +the paper into the incised lines, so that not only is the ink +picked out, but a mould of them is taken on the paper, +hence the very finest lines will give an impression. +Having passed through the press the paper is carefully +peeled off, and thus the print is obtained.</p> + +<p>With regard to the metal employed, copper is commonly +used, since it is soft and easy to work; its softness +however is, in a sense, a disadvantage, since the plate +will soon wear, the finest lines being the first to go, so +that a limited edition of good impressions only is possible. +<span class="pagenum"><a name="page4" id="page4"></a>page 4</span> +To overcome this difficulty, the plate may be faced with +steel, by which means it is rendered very durable.</p> + +<p>Steel, although once popular, is not much used nowadays +owing to its hardness and the rapidity with which +it rusts. As compared with copper engravings, steel gives +a somewhat harder line, whilst copper gives a soft line, +but this, of course, does not mean that steel engravings +are harsh; the finest work can be done on steel and of +remarkable delicacy.</p> + +<p>At the present day line engraving is seldom or never +used as a means of illustrating scientific work. It is obvious +that the average scientist has not the time and he certainly +does not possess the skill to make his own plates; the +engraver must translate the originals into lines, so that +much consultation would be necessary. Further, a line +engraving takes a long time to make, and most publishers +would certainly look at the expense.</p> + +<p>In the past, however, the line engraving was much used, +and very beautiful work was often accomplished. The +following works contain outstanding examples.</p> + +<blockquote><p> +Bojanus: <i>Anatome Testudinis Europaeæ</i>, Vilnae, 1819-1821. +The plates are beautiful engravings by Lehmann +after the drawings by the author.</p> + +<p>Chatin: <i>Anatomie Comparée des Végétaux</i>. Good steel +engravings illustrating the structure of various plants.</p> + +<p>Curtis: <i>Flora Londinensis</i>, London, 1777. The illustrations +are hand-coloured copper engravings by +Sowerby and others, many of which, particularly +the earlier ones, are of outstanding excellence. The +engraving is often nothing more than the mere +outline of the plant, whilst in cases where the +structures are more massive, a certain amount of +shading is used. The colouring is very good indeed, +and it is obvious that much care was taken not only +in the actual painting but also in the choice of +<span class="pagenum"><a name="page5" id="page5"></a>page 5</span> +pigments which, as far as can be judged, are as +fresh now as when first used.</p> + +<p><i>Curtis's Botanical Magazine</i> and <i>Edwards's Botanical +Register</i> contain some excellent examples of hand-coloured +copper engravings.</p> + +<p>Levaillant: <i>Histoire Naturelle des Oiseaux d'Afrique</i>. +Paris, 1805-8. This work contains beautifully coloured +engravings by Feesard. The original drawings were +by Reinold.</p> + +<p>Lyonet: <i>Traite Anatomique de la Chenille</i>. La Haye, 1762. +The plates are amongst the best illustrative of +zoological science.</p> + +<p>Martius: <i>Flora Brasiliensis</i>. The earlier volumes, <i>e.g.</i>, +Vol. 13, Part I, contain excellent engravings.</p> + +<p>Passæus: <i>Hortus Floridus</i>. Arnheim, 1614-17.</p> + +<p>Sowerby and Smith: <i>English Botany</i>. London, 1790-1866. +The illustrations are hand-coloured copper +engravings.</p> + +<p>Thuret et Bornet: <i>Etudes Phycologiques</i>. Paris, 1878. +This work contains the finest plates ever published +in a botanical work. Riocreux drew from the preparations, +and his drawings were engraved on steel +by Picart, Thomas and others. +</p></blockquote> + +<p><span style="font-size: 1.2em"><b>ETCHING.</b></span> Etching is a term very loosely used; +strictly speaking it consists in corroding a metal plate or a +flat stone with acid, or other substance possessed of a +kindred action, so that depressions are formed. A pen and +ink drawing, although usually so termed, is not an etching. +Briefly the method is this: a well polished copper, steel or +zinc plate is covered with a substance, known as the etching +ground, consisting commonly of a mixture of asphaltum, +white wax and pitch, which resists the action of the acid. +The ground may be laid in more than one way; the +simplest, perhaps, is to dissolve the etching ground in +some solvent such as chloroform, which readily volatilises, +<span class="pagenum"><a name="page6" id="page6"></a>page 6</span> +and to pour the solution on to the plate, which is tilted +this way and that until the liquid is evenly distributed; +the excess is poured off and what remains is allowed to +dry, the plate being kept level during the process.</p> + +<p>The plate is then warmed until the ground is softened, +when it is held over a smoking candle and is rapidly +moved here and there so that if properly done the fine +soot is evenly incorporated in the ground. When the +plate is cold, the drawing may be made by cutting through +the etching ground, so as to expose the underlying copper, +with needles of various sizes. The work is then etched +by means of dilute nitric acid.</p> + +<p>When this is satisfactorily accomplished, the ground +is cleaned off, the plate well inked with copperplate ink, +and the surface ink removed by coarse muslin. The plate +is then gone over with fine muslin, but the ink must not +be removed from the depressions; finally the damped +paper is placed in position and impressions obtained +by the use of the copper-plate press.</p> + +<p>Etching, although suitable, especially when natural-printed,* +for the illustration of many scientific subjects, +is but seldom employed at the present time for this purpose; +the preliminary announcement of Warburg's <i>Die +Pflanzenwelt</i>, however, states that some of the illustrations +are etchings.</p> + +<p class="note1"><span style="font-size: 1.2em;">*</span>A plate is said to be natural-printed when all the ink is removed except from +the depressions; in artificial printing some ink is allowed to remain on the +flat parts. Artists frequently, after removing the superfluous ink, lightly dab +the plate in order to make the pigment spread slightly beyond the actual limits +of the depressions; this is known as <i>retroussage</i>. +</p> + +<p><span style="font-size: 1.2em"><b>SOFT-GROUND ETCHING.</b></span> This is a somewhat +rare method of reproduction nowadays; it may, +however, be described briefly, for it would appear to +be suitable for scientific purposes, since it should not +prove a matter of great difficulty for an author who is +a sufficiently skilled draughtsman to make his own +plates. The polished copper plate is laid with ordinary +<span class="pagenum"><a name="page7" id="page7"></a>page 7</span> +ground to which is added lard in a quantity according to +the warmth of the weather.</p> + +<p>Over the plate is then placed a sheet, larger than the +plate by an inch or two, of damp, thin, grained paper, +the edges of which are folded over and pasted to the back +of the plate. When the paper is dry it will be well stretched +and in close contact with the plate. With the hand resting +on a bridge, in order to avoid inadvertent touching of +the plate, the drawing is made on the paper with a pencil +of a hardness suited to the softness or otherwise of the +etching ground. When the drawing is finished the paper +is carefully removed; wherever the pencil has been used, +the etching ground will adhere to the paper, so that in +such places the metal will be exposed. The plate is then +etched and printed as in the normal process.</p> + +<p>No reproductions of drawings of scientific subjects +apparently have been reproduced by this method. +Examples can conveniently be examined in <i>The Seven +Lamps of Architecture</i> by Ruskin.</p> + +<p><span style="font-size: 1.2em"><b>MEZZOTINT.</b></span> The characteristic feature of mezzotint +is that the subject is translated into tones rather +than lines as in the preceding intaglio methods.</p> + +<p>The surface of a smooth metal plate—usually copper—is +raised into innumerable and minute projections by +going over it in all directions with a curved steel tool, +known as a rocker, the edge of which is finely toothed. +An impression taken of the plate in this condition will +give a deep rich tone. The high lights are obtained by +scraping and burnishing away the elevations so that there +are no pits left to hold the ink, and, similarly, intermediate +tones are produced by partly removing the pile so that +the pits are made of varying degrees of shallowness and +consequently will print in tones according to their depth.</p> + +<p>Impressions are taken in the same way as in the case of +etchings.</p> +<span class="pagenum"><a name="page8" id="page8"></a>page 8</span> + +<p>Mezzotint apparently has never been used for the +reproduction of scientific subjects. Indeed, in a sense, +this process is much too artistic for the purpose. At their +best, illustrations reproduced by this method have +mystery and depth and give the imagination much employ; +in a word, they are subjective rather than objective, +qualities unsuited for our purpose.</p> + +<p><span style="font-size: 1.2em"><b>PHOTOGRAVURE.</b></span> Photogravure may next be +considered, for although it is a photo-mechanical process, +it corresponds to mezzotint. Excellent results may be +obtained by its use provided the drawings—usually +executed in monochrome such as sepia—be really good, +otherwise they are hardly worth reproducing by this +relatively expensive method.*</p> + +<p class="note1"><span style="font-size: 1.2em;">*</span>This account refers only to plates made and printed entirely by hand, +not to photogravure for printing on a rotary machine.</p> + +<p>Photogravure is particularly suitable for the reproduction +of drawings showing a large amount of detail and +made up of a variety of tones rather than lines or stipple.</p> + +<p>The photographic part of the process is essentially the +same as making a carbon print from a photographic +negative. This consists in exposing under the negative +the carbon tissue, which is a mixture of gelatine, in which +is dissolved bichromate of potash, and a suitable pigment. +Such a film of bichromate gelatine is, when dry, +sensitive to light. If no light gains access to it, the gelatine +is readily soluble in warm water; if light acts upon it, +the gelatine becomes insoluble in proportion to the +degree of its exposure. Obviously, the pigment will be +retained in varying degrees according to the relative +insolubility of the different parts of the gelatine.</p> + +<p>The carbon tissue having been exposed, is rolled down +on a wet sheet of paper covered with some adhesive and +is dried under pressure. The paper is then soaked in +warm water when the basis of the carbon tissue easily +<span class="pagenum"><a name="page9" id="page9"></a>page 9</span> +peels off; the picture is developed by laving in warm +water, which will dissolve the gelatine in proportion to +its exposure to the light. The print when dry is remarkably +permanent and, from the picturesque point of view, is +infinitely superior to the ordinary silver print.</p> + +<p>The method of making the photogravure plate is, in +outline, as follows:</p> + +<p>The original drawing is photographed, and it is very +important that the negative should be as perfect as +possible.</p> + +<p>From the negative, a positive is made upon transparency +carbon tissue which is mounted upon a sheet of plate +glass. The procedure is, in essentials, exactly the same +as described above for the making of a carbon print. +This positive when dry may be touched up; after which +a negative, which also may be touched up, is made from +it upon an ordinary sheet of carbon tissue.</p> + +<p>The negative so obtained is transferred to a prepared +plate of copper, developed with warm water and +dried.</p> + +<p>The copper plate is prepared as follows: after being +well polished until quite free from all scratches, the +surface is dusted over with finely powdered resin or, more +usually, bitumen. The plate is then heated until the dust +adheres.</p> + +<p>After the carbon negative has been stuck on to the +plate, developed and dried, the margins and back of the +copper are protected with an acid-resisting varnish. When +dry, the plate is placed in the etching bath of nitric acid +or, more generally, of ferric chloride. The etching fluid +will pass through the thinnest parts of the negative first, +so that the surface of the copper will be etched to a degree +corresponding to the thickness of the gelatine. The high +lights on the negative obviously will be represented by +thick coatings of gelatine, consequently such parts will +be but slightly etched and vice versâ.</p> +<span class="pagenum"><a name="page10" id="page10"></a>page 10</span> + +<p>If the plate had not been laid with resin, the surface after +etching would show more or less extensive depressions +and elevations; but the grains of resin protect the copper +immediately beneath them from the action of the acid, +which consequently can only dissolve the exposed parts +of the metal between the resinous particles. The result is, +therefore, that the plate is covered over with numberless +fine pits of varying depths. The deepest ones will, on +printing, give the darkest tones, since they will hold more +ink, the shallower ones will give the lighter tones, whilst +the shallowest and those parts unetched will give the +high lights.</p> + +<p>The plate is usually etched three or four times successively +in varying strengths of fluid, after which the etching +ground and gelatine is cleaned off.</p> + +<p>A strong copper-plate ink is then well rubbed in by +means of a dabber, after which the ink from the surface +is removed, first with a coarse piece of muslin and finally, +with fine muslin. The ink must not be removed from the +pits.</p> + +<p>The first pull is then taken as in a line engraving with +a copper-plate press, and its appearance shows what +corrections are necessary. The plate nearly always +requires a certain amount of engraving; the high lights +may be improved by means of a burnisher, the shadows +by means of a rocker or a roulette—a small steel wheel +the rim of which is beset with fine teeth—and so on. +Finally, if a large edition is required, the plate is steel +faced.</p> + +<p>Although much used for the reproduction of pictures, +photogravure is too rarely employed for scientific purposes; +this is to be regretted, for the process is admirably +suited to the reproduction of photographs and drawings +with delicate tones. As compared with the usual half-tone, +the cost is high, and this no doubt militates against its +use.</p> +<span class="pagenum"><a name="page11" id="page11"></a>page 11</span> + +<p>Examples of outstanding excellence will be found in +the <i>New Phytologist</i>, Vol. xi, 1912, plates 5 and 6. These +are absolute facsimiles of the original drawings by Mr. +McLean, both as regards colour and reproduction of +tones. Plate 8 may also be examined and compared +with plates 9 and 10 which are reproductions of the +same subject in collotype and half-tone respectively.</p> + +<div class="figcenter" style="width: auto;"><a href="images/tailpiece_p11-700.png"><img src="images/tailpiece_p11-400.png" width="400" height="264" alt="tailpiece-peacock" /></a></div> + +<span class="pagenum"><a name="page13" id="page13"></a>page 13</span> + +<h4 style="margin-top: 3em;">PLANE SURFACE PRINTING</h4> +<span class="pagenum"><a name="page14" id="page14"></a>page 14</span> + +<div class="figcenter" style="width: auto;"><a href="images/plate_1-1000.png"><img src="images/plate_1a-600.png" width="600" height="422" alt="Plate 1. An original lithograph by Mr. Harry Becker." /></a> +<h4><span class="sc">Plate 1.</span>—An original lithograph by Mr. Harry Becker.</h4></div> +<span class="pagenum"><a name="page15" id="page15"></a>page 15</span> + +<h2 style="margin-top: 3em;">PLANE SURFACE PRINTING</h2> + +<p style="line-height: 1%; margin-top: -0.5em;"> </p> +<p class="dropcap"><span class="dcap"> +L</span> +<b>ITHOGRAPHY.</b> Of these methods of printing, +lithography is the outstanding example: it is a +method of reproduction possessed of great +possibilities, for by its employment a facsimile of any +drawing can be obtained.</p> + +<p>As a means of artistic expression it ranks high amongst +the graphic arts, and, for the reproduction of drawings +of a scientific nature, it is very popular, since it meets +most requirements and is comparatively inexpensive.</p> + +<p>The art, which was discovered by Senefelder towards +the end of the eighteenth century, depends on the fact +that grease and water are immiscible: a drawing made +with a greasy pigment upon a suitable surface adheres +very strongly, whilst those parts free from it retain +water, so that when damped and rolled up (<i>i.e.</i>, inked), +the ink used will stick only to the lines, etc., of the +drawing, but not to the other parts.</p> + +<p>Clearly the surface is all important, and this is provided +by lithographic stone, a limestone occurring in Germany, +France, England and Canada. The best stones occur at +Solenhofen near Munich, those from other localities +being inferior in quality. Incidentally it may be mentioned +that zinc and aluminium plates are not infrequently used +in place of stone.</p> + +<p>Lithographic stones vary in hardness, colour and grain. +For the best work the stone should be homogeneous and +of a hardness suitable for the subject; the colour affords +an indication of the hardness, the lighter-coloured stones, +which are much the commoner, being softer than the +darker.</p> + +<p>There are two modes of procedure; the drawing may +<span class="pagenum"><a name="page16" id="page16"></a>page 16</span> +be made direct on the stone with lithographic ink or +crayon—both being mixtures of tallow, wax, soap and +shellac, with a sufficiency of pigment to render the +drawing visible to the artist—or else the drawing may be +made upon transfer paper.</p> + +<p>The former method, although the more satisfactory +and often used by artists, is seldom pursued in scientific +drawings except when professional draughtsmen are +employed. In such cases it may be necessary to reverse +the drawing, which is conveniently done by viewing it +in a mirror, and, of course, all lettering must be reversed.</p> + +<p>The majority of amateur draughtsmen make their +drawings in pencil or ink and these the lithographer +traces upon lithographic transfer paper and transfers +them to the stone; he, the lithographer, may merely +trace the salient features and work the drawing up on +the stone. The transfer papers are coated with gelatine, +starch or gum, or mixtures of these substances, the idea +being to interpose between the real paper and the pigment—in +the form of lithographic crayon or ink—some +substance soluble in water which will hold the pigment +and prevent it soaking into the paper, so that a transfer +has only to be damped through the back, pressed on to +the stone and peeled off. The work, together with more +or less of the film, will thus be transferred on to the +stone and, of course, will be reversed, since the part +uppermost on the stone will be the back of the original +drawing.</p> + +<p>The original drawings may be made upon the transfer +paper direct, and in so doing mistakes in tracing will be +obviated. Suitable papers are made for various purposes, +e.g., smooth for ink work and variously granulated for +crayon (see Plate 1, which was drawn by Mr. Harry +Becker on transfer paper).</p> + +<p>Another advantage in drawing directly upon the transfer +paper is that the draughtsman can make corrections +<span class="pagenum"><a name="page17" id="page17"></a>page 17</span> +pretty easily for, if needs be, a bad piece of work can be +entirely cut out and a fresh piece of paper inserted.</p> + +<p>Assuming that the transfer method has been employed, +the stone must be prepared according as the drawing is +made with ink or with crayon.</p> + +<p>The stone is first thoroughly ground, in order to rid it +of all traces of previous work, and then polished for ink +work or grained—<i>i.e.</i> roughened—for crayon work, the +small points produced taking up the crayon in proportion +to the amount present on the transfer and the pressure +used.</p> + +<p>The transfer is then damped with water, sometimes +with a dilute solution of nitric acid, and placed in position +on the stone, which is then passed two or three times +through the lithographic press until dry. Then the back +of the paper is damped and the sheet peeled off.</p> + +<p>The stone is next proved, <i>i.e.</i>, prepared for printing.</p> + +<p>It is first carefully examined for broken lines and other +blemishes, which are touched up with ink or crayon. +The stone is then painted over with a solution of gum in +water which is allowed to dry, it is then washed in water +and rolled up with ink. The drawing will now be clearly +visible, for if properly inked the clear parts of the stone +will not take the pigment, so that any parts which require +cleaning up may be deleted. This is accomplished by +means of a pencil of snake stone, a piece of pumice stone, +an acid stump—a rod of hard wood, the sharpened end +of which is dipped into nitric acid—or with a scraper. +The stone is again washed and rolled up strongly with ink +and etched with a dilute solution of nitric acid which is +applied with a sponge; then the surface is again gummed +and the stone allowed to dry. It is sometimes necessary +to re-etch the stone; if so, the damp stone is rolled up +with thin ink and allowed to dry, it is then dusted over +with finely powdered resin, the superfluous resin is +removed by means of a wet sponge, and the surface is +<span class="pagenum"><a name="page18" id="page18"></a>page 18</span> +painted over with a solution of gum arabic mixed with +dilute nitric acid. If the resin is well incorporated with +the ink, the work will suffer no damage in the process. +The acid gum is then dabbed off with a rag, the stone is +cleaned up with turpentine, rolled up once more, gummed +and finally set aside to dry.</p> + +<p>All this appears complicated, but it is very necessary +to get a good surface for printing. The action of the gum +does not appear to be clearly understood, the nitric acid +obviously will etch the stone, so that the gum will easily +penetrate. It is sometimes supposed that the arabic acid +of the gum enters into a chemical composition with the +calcium carbonate, making a film which is the real ink-resisting +surface. This film has not a long life, so that in +printing it is necessary to renew it periodically by the +application of gum solution.</p> + +<p>If possible, the stone should be allowed to rest for a +day or two after proving, in order that the ink may sink +well in.</p> + +<p>Before printing, the gum is washed off and the stone +allowed to remain in the press-room until its temperature +is the same as its surroundings. The stone is then +thoroughly and evenly damped all over, placed in the +press, and rolled up with lithographic ink; the paper +is then laid on, and the whole passed through the lithographic +press. After the first few pulls it will be seen +whether all is well. The essentials of a good impression +are these: the lines must be black and not grey, provided +black ink is used; the lines must not be wider +or blacker ("smutty") than those on the stone, nor must +they be ragged or broken ("rotten").</p> + +<p>In printing, the stone must be damped and inked +before each impression is taken, and occasionally re-gumming +is required. Good printing requires a considerable +amount of ability, especially in the case of crayon +drawings.</p> +<span class="pagenum"><a name="page19" id="page19"></a>page 19</span> + +<p>The paper used is a very important matter, the selection +of which can be safely left to the lithographer, provided +he be a good one, unless the author possesses the necessary +technical knowledge. If a smooth paper is required, +and the paper is not to be damped before printing, India +paper is best and plate paper next best. All coarse or +grained papers must be damped before printing.</p> + +<p>As has already been remarked, lithography is a good +process for scientific work; but, unfortunately, considering +the number of lithographic plates published, +really first-class examples are rare. This is largely due +to the original draughtsman; it is unreasonable to +expect a lithographer, in all probability ignorant of the +subject of the plate, to turn out first-class reproductions +of drawings which are obviously bad. On the other hand, +lithographers vary greatly in their capabilities, and +indifferent plates may be entirely due to their ability not +being first rate.</p> + +<p>As drawings have to be traced, mistakes are apt to +occur; the proofs should, therefore, be carefully examined, +for a certain amount of correction can be made +on the stone.</p> + +<p>The following works contain excellent lithographs, +which should be studied by those interested in the +subject.</p> + +<blockquote><p> +Bornet et Thuret: <i>Notes Algologiques</i>. Paris, 1876-1880. +This contains some of the best work, illustrative +of science, known to the present author. The +original drawings mostly were made by Bornet, +and the lithography was carried out by Riocreux—one +of the best if not the greatest of botanical +artists—Arnoul, Picart and Pierre.</p> + +<p>Davis and Thurnam: <i>Crania Britannica</i>. London, 1865.</p> + +<p>Mirbel: <i>Sur le Cambium</i>, Paris, 1842. The plates provide +excellent examples of ink lithography by Laplante.</p> +<span class="pagenum"><a name="page20" id="page20"></a>page 20</span> + +<p>Von Mohl: <i>Schriften botanischen Inhalts</i>. Tübingen, 1845. +Good examples by Federer. +</p></blockquote> + +<p>The first volumes of the <i>Annales des Sciences Naturelles</i> +(Paris) may be referred to for lithographic work earlier +than the above (1820).</p> + +<p>For more modern examples the following may be +consulted:</p> + +<blockquote><p> +Blackman and Welsford: <i>Fertilisation in Lilium</i>, Annals +of Botany, Vol. 27, 1913.</p> + +<p>Gravis: <i>Recherches anatomiques sur les organes végétatifs +de l'Urtica Dioica</i>, Bruxelles, 1885. This memoir +contains both good and indifferent plates.</p> + +<p>Keibel: <i>Normentafeln zu Entwicklungsgeschichte der +Wirbeltiere</i>, Jena, 1904.</p> + +<p>Reed: <i>A Study of the Enzyme-secreting Cells in the +Seedlings of Zea Mais and Phœnix dactylifera</i>. +Annals of Botany, Vol. 18, 1904.</p> + +<p>Semon: <i>Zoologische Forschungsreisen in Australien</i>, Jena, +1904.</p> + +<p>Vaizey: <i>On the Morphology of the Sporophyte of Splachnum +luteum</i>, Annals of Botany, Vol. 5, 1890.</p> + +<p>Woodburn: <i>Spermatogenesis in Blasia pusilla</i>, Annals of +Botany, Vol. 27, 1913. +</p></blockquote> + +<p>Several memoirs in the <i>Fauna und Flora des Golfes +von Neapel</i> (Berlin) are illustrated by excellent lithographic +plates. Many good examples of chromolithography also +will be found there.</p> + +<p><span style="font-size: 1.2em"><b>CHROMOLITHOGRAPHY.</b></span> Lithography is much +used for the reproduction of coloured pictures and illustrations, +the process being termed chromolithography. +The principles involved are the same as for ordinary +work, but it is necessary to print from several stones, +one for each colour. It is obvious that much skill is +required, for the employment of different colours will +<span class="pagenum"><a name="page21" id="page21"></a>page 21</span> +give a large number of secondary and tertiary tints when +printed one above the other in various combinations. +Thus, by printing part of a design in yellow and the +other part in blue, the finished product would show +three colours—yellow, green and blue, and by the use +of three primary colours a large number of different +tints may be obtained.</p> + +<p>As already mentioned, each colour is printed by a +separate stone, there is thus no limit—excepting that of +expense—to the number of different colours which can +be obtained.</p> + +<p>In practice it is usual to make an outline of the essential +parts of the composition on a stone, known as the keystone, +which is not necessarily used in printing the +picture. An impression of this outline is taken upon a sheet +of paper, which is used to transfer the design on to the +stones, on each of which the artist will draw only those parts +which he desires to be printed in one particular pigment.</p> + +<p>Although the sequence of colours is generally blue, +red and yellow, it is obvious that various changes in this +order must be made according to the colours used and +the exact tint required. For instance, a body colour such +as cadmium yellow would precede a glaze such as madder-lake; +again, two distinct tints may be obtained from red +and blue, for example, according to the order of printing—red +upon blue will give a mauve, whilst blue upon red +will give a purple.</p> + +<p>A knowledge of pigments is thus all important, and in +printing, the superposition must be perfect.</p> + +<p>Plate 2 is an example of a chromolithograph. Miss O. +Johnston first drew the outline of the plant, which was +phototransferred on to the stone. An impression was then +pulled and tinted by the artist, and from this tinted impression +the colour stones were made by the lithographer. +It may be added that only three colours were used in +printing the plate.</p> +<span class="pagenum"><a name="page22" id="page22"></a>page 22</span> + +<p>Examples:</p> + +<blockquote><p> +Baur: <i>Einführung in die experimentelle Vererbungslehre</i> +(Plate 1). Berlin, 1911.</p> + +<p>Bruce and others: <i>A Note on the Occurrence of a +Trypanosome in the African Elephant</i>. Proceedings +of the Royal Society of London, B. Vol. 81, 1909.</p> + +<p>Cropper: <i>The Development of a Parasite of Earthworms</i>. +<i>Id.</i> Vol. 85, 1912.</p> + +<p>Oliver: <i>On Sarcodes sanguinea</i>. Annals of Botany, Vol. 4, +1889-1891.</p> + +<p>Rubbel: <i>UEber Perlen</i> ... Zoologische Jahrbuecher, Vol. +32, 1911-12.</p> + +<p>Biometrika, 1906-7, Vol. 5, Plate 23. +</p></blockquote> + +<p>Mention has been made of the value of a knowledge of +colours. The subject is much too extensive to be considered +adequately on the present occasion even if it +were desirable; its importance, however, warrants a few +passing remarks.*</p> + +<p class="note1"><span style="font-size: 1.2em;">*</span>See Ridgway: <i>Color Standards and Color Nomenclature</i>.</p> + +<p>No two people will describe in the same way the colour +of, say, a rose petal; both will have a different conception +of the colour "crimson." The majority have but a limited +sense of colour, and even when this faculty is possessed, +the personal equation looms large; further, the ordinary +names of colours are quite inadequate for descriptive +purposes. For these reasons the importance of a scientific +system of colour nomenclature and colour standards is +all important. By the use of such a scheme, the exact +colour of an object can be found by comparison with an +adequate chart, and the name there given will convey +to others exactly what colour is described or desired. +The plumage of a bird or the colour of a flower can thus +be described correctly, and an author can indicate exactly +the colour desired in certain parts of a chromolithograph +or other reproduction in colour.</p> + +<a name="plate2" id="plate2"></a> + +<div class="figcenter" style="width: auto;"><a href="images/plate_2-800.png"><img src="images/plate_2a-270.png" width="270" height="487" alt="Plate 2. Geranium Columbinum." /></a> +<h4><span class="sc">Plate 2.—Geranium Columbinum.</span></h4> +<p class="center" style="margin-top: -1em;">A chromolithographic reproduction of a drawing by Miss O. Johnston</p></div> + +<span class="pagenum"><a name="page23" id="page23"></a>page 23</span> + +<p><span style="font-size: 1.2em"><b>PHOTOLITHOGRAPHIC PROCESSES.</b></span>—Of these +methods of reproduction there are several, their value +lying in the fact that the originals can be reduced or +enlarged with the greatest of ease. The general principles +are as follows.</p> + +<p>A photographic negative is taken of the original drawing +and a positive made on a film of bichromate gelatine. +Wherever light reaches the film, the gelatine is rendered +more or less insoluble according to the intensity of the +light acting upon it; through the dark parts of the +negative but little light will pass, so that the gelatine will +remain soluble.</p> + +<p>The exposure of the positive having been made, the +film, which may be mounted on paper, is inked with +lithographic ink in the dark room and then washed. +The pigment will adhere to those parts acted on by light, +but will wash away from those regions unacted upon; +obviously the half-tones will retain ink in direct proportion +to their density.</p> + +<p>The developed positive is then transferred to a stone +or zinc plate and impressions taken as in pure lithography +for the dark parts are resistant to water and will take the +ink, whilst the high lights will retain water and so will not +be inked. The intermediate tones will take the pigment +according to their density.</p> + +<p>In distinction to the previous methods, corrections +cannot be made except in so far as the negative can be +touched up.</p> + +<p><span style="font-size: 1.2em"><b>COLLOTYPE.</b></span>—Of the various photolithographic +methods which have from time to time been employed, +collotype is the one in most general use at the present +time, especially for the reproduction of photographs.</p> + +<p>Collotype is a simple process which does not require +so extensive a technical knowledge and ability as some +of those previously described. But notwithstanding this, +<span class="pagenum"><a name="page24" id="page24"></a>page 24</span> +the results are sometimes unsatisfactory and unequal; +faults due to indifferent originals and to unsatisfactory +conditions obtaining in the work rooms. The great +drawbacks to good collotype are cold and dampness, +and it is for these reasons that continental firms, blessed +with a more stable climate, often produce much the best +work. Provided the workshops are properly heated, the +collotypers of this country ought to be able to turn out +good work at all times of the year; indeed, the best firms +do.</p> + +<p>For this and for other processes in which photographs +form the originals to be reproduced, authors should +send the negative to the collotyper; if this be impossible, +positives of the best possible quality, printed on ordinary +P.O.P. paper, toned to various shades of purple, and +also on smooth bromide paper, in ordinary black tones, +should be provided in order that the collotyper can +choose the print he most prefers to work with. Also, it +is usual to glaze the prints.</p> + +<p>The method is as follows. A piece of british plate +glass, about half-an-inch in thickness, is ground on one +side with fine emery powder, and then thoroughly washed +and dried. The plate is covered with a filtered mixture +of the colloids sodium silicate and dextrine or albumin, +and placed in a warm oven to dry. If metal plates are +used, such as zinc or copper, this preliminary coating is +unnecessary; glass plates, however, must have the substratum +in order that the sensitised gelatine—which is +next put on—may stick.</p> + +<p>When the plate is dry, it is thoroughly washed with +water in order to remove any free silicate; it is then +dried and put away until required for use.</p> + +<p>The sensitising solution is made up of gelatine and +bichromate of potash dissolved in water; before use it +is filtered, freed from air bubbles and heated to not more +than 120° F. The plate is now placed on a stand, which +<span class="pagenum"><a name="page25" id="page25"></a>page 25</span> +is provided with levelling screws, in the oven, and, when +the temperature has reached 120° F., an amount of the +bichromate gelatine solution sufficient to make a +thickness of film proper for the mode of printing to be +employed is poured upon the plate.</p> + +<p>The oven is kept at a constant temperature, 120° F., +until the gelatine is dry, when it is allowed to cool gradually.</p> + +<p>Whilst the gelatine is setting, precautions against +vibration must be taken else the plate will be spoilt.</p> + +<p>When dry, the collotype plate is sensitive to light and +moisture; its surface shows a more or less regular series +of convolutions which resemble those of the outer surface +of the human brain, although, of course, very much +smaller. The character of the grain is very important, +for if it be too fine it will not take up a sufficiency of ink, +and, on the other hand, if too coarse it will yield coarse +impressions.</p> + +<p>A reversed negative, of a quality beyond reproach, +must be made of the original; if the subject is dark or +has heavy shadows the negative is frequently slightly +over exposed so as to soften them.</p> + +<p>The collotype plate is then exposed under the +negative and washed in cold water until the yellow bichromate +no longer comes away. It is then dried.</p> + +<p>In printing, the plate is damped and rolled up with +ink as in lithographic printing; the amount of ink +adhering to the film depends on the extent to which +the different parts have been acted on by the light, as +has already been mentioned. The moistening of the plate—mis-termed +etching—is best done with dilute glycerine +containing 75 per cent. of water, which when first applied +should be allowed to remain on for about half-an-hour. +The excess of moisture is taken up with a sponge or a ball +of rag, and then the plate is inked and printed in a lithographic +or a collotype press. The picture is usually masked +with tin foil in order that its edges may be quite clean.</p> +<span class="pagenum"><a name="page26" id="page26"></a>page 26</span> + +<p>Of the faults which may occur, the following may be +alluded to. A mottled appearance may obtain in the high +lights; this is due to the coating of gelatine being too +thick. More commonly, the reproductions may appear +flat owing to the degradation of the high lights; this is +a sign that the sensitive film has been acted upon by +moisture during its critical existence between the drying +and the washing out of the potassium bichromate, or +that the temperature has been too low.</p> + +<p>The following contain good examples of collotype.</p> + +<blockquote><p> +Karsten and Schenck: <i>Vegetationsbilder</i>, Jena.</p> + +<p>Oliver: <i>Notes on Trigonocarpus and Polylophospermum</i>. +New Phytologist, Vol. 3, 1904.</p> + +<p>Semon: <i>Zoologische Forschungsreisen in Australien</i>. +Jena. 1912.</p> + +<p>Thompson: <i>The Anatomy and Relationships of the +Gnetales</i>. Annals of Botany, Vol. 26, 1912.</p> + +<p>See also Plates 3, 4, 5 and 9 in the present work. +</p></blockquote> + +<p><span style="font-size: 1.2em"><b>THE PREPARATION OF ILLUSTRATED +PAGES.</b></span> Of the processes dealt with, photogravure +lithography and collotype are those most generally used +at the present day for the printing of plates or insets. +Half-tone also is employed, a process which will be considered +later since it is essentially relief printing. This, +therefore, is a convenient opportunity to make a few +general observations on plates.</p> + +<p>Plates should only be employed for the reproduction +of subjects of such complexity that cannot be reproduced +satisfactorily by figures in the text.</p> + +<p>A plate or page made up of several illustrations should +look well as a whole; in other words, it should not outrage +all the canons of composition, it should have some pictorial +effect. At the same time, for facility of reference, +the individual figures should run in a convenient sequence. +<span class="pagenum"><a name="page27" id="page27"></a>page 27</span> +This latter point is so important that a plate composed +really well is distinctly rare, for a compromise nearly +always has to be made. At the same time there are, apparently, +comparatively few authors who pay much +attention to plate design.</p> + +<p>Although it is not desired to write of the laws of pictorial +composition, attention may be drawn to a few points +which are amongst those generally neglected.</p> + +<p>The figures should not be crowded together; a reasonable +amount of margin should be left around each. They +should be arranged, as far as possible, in such a way that +a sense of balance is maintained. As to how this is to be +accomplished will depend upon the nature of the illustrations; +if they are all about equal in tone, the largest +ones should preponderate towards the base of the plate, +and not <i>vice versâ</i>. The difference which this makes will +be obvious if the two accompanying illustrations (Figs. 1 +and 2, Plate 3) be compared. The first is a reduced copy +of the plate as it was published: it will be noticed that +it has a top-heavy appearance, which is corrected in the +second figure by the simple device of turning it upside +down.</p> + +<a name="plate3" id="plate3"></a> +<div class="figcenter" style="width: auto"><a href="images/plate_3-1-1000.png"><img src="images/plate_3a-1-500.png" width="500" height="366" alt="Plate 3. 1" /></a> +<h4><span class="sc">Plate 3. - 1</span></h4></div> + +<div class="figcenter" style="width: auto;"><a href="images/plate_3-2-1000.png"><img src="images/plate_3a-2-500.png" width="500" height="369" alt="Plate 3. 2" /></a> +<h4><span class="sc">Plate 3. - 2</span></h4></div> + +<p>If, on the other hand, the figures are some lighter and +others darker, the latter should form the base, since low +tones give the idea of solidity; this is so marked that in +cases where the figures vary much in size and tone, the +darker ones may nearly always be situated at the base or +at any rate low down on the plate unless they are very +much smaller than the lighter toned ones.*</p> + +<p class="note1"><span style="font-size: 1.2em;">*</span>If, of course, the reader understands chiaroscuro, he will take no +notice of this paragraph, but arrange his plates in accordance with his +ability.</p> + +<p>An examination of the figures on Plates 4 and 5 will +roughly illustrate these points. The upper figure of +Plate 4 is well designed, and no improvement could be +made, bearing in mind the compromise alluded to above. +The lower figure is, however, not so good, it was +<span class="pagenum"><a name="page28" id="page28"></a>page 28</span> +obviously a difficult one to arrange; it would have been +improved if Figs. 23, 26 and 28 could have been +placed in the top tier, but this would have seriously +disturbed the sequence. The first illustration on Plate 5 +is well designed; it would, however, have been improved +by interchanging 8A and 11B.</p> + +<div class="figcenter" style="width: auto;"><a href="images/plate_4-1-1000.png"><img src="images/plate_4a-1-500.png" width="500" height="373" alt="Plate 4. 1" /></a> +<h4><span class="sc">Plate 4. - 1</span></h4></div> + +<div class="figcenter" style="width: auto;"><a href="images/plate_4-2-1000.png"><img src="images/plate_4a-2-500.png" width="500" height="378" alt="Plate 4. 2" /></a> +<h4><span class="sc">Plate 4. - 2</span></h4></div> + +<div class="figcenter" style="width: auto;"><a href="images/plate_5-1-800.png"><img src="images/plate_5a-1-350.png" width="350" height="460" alt="Plate 5. 1" /></a> +<h4><span class="sc">Plate 5. - 1</span></h4></div> + +<div class="figleft" style="width: auto; margin-left: 8em;"><a href="images/plate_5-2-400.png"><img src="images/plate_5a-2-162.png" width="162" height="300" alt="Plate 5. 2" /></a> +<h4><span class="sc">Plate 5. - 2</span></h4></div> + +<div class="figright" style="width: auto; margin-right: 8em;"><a href="images/plate_5-3-400.png"><img src="images/plate_5a-3-160.png" width="160" height="300" alt="Plate 5. 3" /></a> +<h4><span class="sc">Plate 5. - 3</span></h4></div> +<p style="clear: both;"> </p> + +<p>We may now pass on to the individual figures; these +should shew the essential features, together with some +surrounding and comparatively extraneous matter; often +there is included too much of unimportance and its retention +means a waste of valuable space. The first thing +to do, therefore, is to trim, if needs be, the figures; their +shape is more or less immaterial, provided that in cases +where there are a large number of illustrations on one +plate, they are not all alike. The American fashion of +circular figures is particularly displeasing, at any rate to +the author.</p> + +<p>Having trimmed the figures, the next point to decide +is whether any require reduction; if they do, cut out +pieces of paper (referred to as patterns below) of the size +which the figures will ultimately appear: on the whole, +it is better to avoid reduction of the originals, for without +a good deal of experience it is very difficult to judge +exactly what the result will be; a good idea, however, +may be gained by the use of a diminishing +glass.</p> + +<p>The size of the available surface of the plate should +now be ruled on a white sheet of fairly thick cardboard, +and the figures, or their patterns, arranged so as to be +easy of reference, to compose as well as may be, and +spaced in such a way that, in the case of a quarto plate +to be folded vertically, no figure is placed so that +the fold will pass through its centre. Nothing is more +irritating than having an illustration spoilt in this +way.</p> + +<p>All this may be done by arranging in different ways +<span class="pagenum"><a name="page29" id="page29"></a>page 29</span> +until a satisfactory result is obtained, a process which +may take an hour or two. The figures should then be +pasted down, covered with several sheets of blotting paper +and placed in a press. A press is seldom available; when +such is the case, a number of heavy books serve equally +well.</p> + +<p>The lettering must next be attended to. The individual +figures are usually designated by numbers; this is a bad +method, since it involves referring to the description of +the plate. The best way is to use a number, and after it +to add the name of the plant or animal, and, if needs be, +a description as short as may be. If the author can "print" +or write reasonably well, well and good; if not, it is +better to attach a slip to the plate with full directions +relating to lettering, and to write in pencil on the plate +the titles, etc., required in the proper places for the +guidance of the craftsman. The typewriter is sometimes +employed for this purpose by authors; it is purely a +matter of taste, but some readers feel a slight shock when +this method is resorted to.</p> + +<p>In some cases a key to the plate printed on tough +translucent tissue paper and having the necessary +information, guide lines, etc., is inserted with the plate.*</p> + +<p class="note1"><span style="font-size: 1.2em;">*</span>See Kerner and Oliver: <i>Natural History of Plants</i> (First Edition) London, +1894.</p> + +<p>In the case of glossy chromolithographs this practice +is best avoided, for the key is apt to stick to the plate if +too much pressure is used when the book is bound.</p> + +<p>With regard to the "catch letters" used to indicate +different parts: these should be as obvious as possible, +and the guide lines should be either in black or in white +ink, according to the general tone of the illustration. +These lines should be conspicuous without being heavy. +Not infrequently they, together with the lettering, +are printed on the plate by a second impression in +red ink.</p> +<span class="pagenum"><a name="page30" id="page30"></a>page 30</span> + +<p>The foregoing is primarily the business of the author; +with regard to editors and publishers, all plates should +be mounted in a manner to facilitate reference and should +be printed on suitable paper; the former is seldom or +never done. All plates which must be constantly referred +to in reading the text should have a selvedge as broad +as the book, so that when unfolded the whole plate is +visible, no matter what page is being read. This would, +no doubt, prove an additional expense, but this should +not militate against the suggestion here made, not by +any means an innovation, for in many cases it would +save the expense of mounting on guards, and, further, +the additional expenditure could be saved several times +over in other ways.</p> + +<p>With regard to paper, this generally is satisfactory; +unfortunately, highly glazed paper, mis-termed art paper, +with an enamelled or chromo surface, and consisting +chiefly of china clay and size, is generally used for printing +the best half-tone reproductions. For this purpose a +paper with a suitable surface, obtained by means other +than those mentioned and not too costly, is highly desirable, +since art paper has the reputation of being not at +all permanent, owing to the deleterious action of moisture, +and is somewhat brittle. When used, art paper, if folded, +should have a proper paper hinge along the fold.</p> + +<p>Half-tones are occasionally printed on a kind of vegetable +parchment, a paper which should be more extensively +used since it will sometimes, but not always, give as good +a reproduction as art paper, and the final result is more +pleasing from the artistic point of view.</p> +<a name="t30" id="t30"></a> +<div class="figcenter" style="width: auto;"><a href="images/tailpiece_p30-800.png"><img src="images/tailpiece_p30a-400.png" width="400" height="98" alt="tailpiece" /></a> +<p class="center">G. Oliver, del.</p></div> +<span class="pagenum"><a name="page31" id="page31"></a>page 31</span> + +<h2 style="margin-top: 3em;">RELIEF PRINTING</h2> +<span class="pagenum"><a name="page32" id="page32"></a>page 32</span> + +<div class="figcenter" style="width: auto;"><a href="images/fig_1-1000.png"><img src="images/fig_1a-400.png" width="400" height="474" alt="Fig. 1" /></a> + +<table align="center" summary="poem"> +<tr> + <td> +<p>Little maid, little maid,</p> +<p>Whither goest thou?</p> +<p>Down in the meadow</p> +<p>To milk my cow.</p> + </td> +</tr> +</table> + +<p class="center" style="margin-top: 3em;">Fig. 1.—A wood engraving, by Edmund Evans, from<br /> +the original drawing by Kate Greenaway.</p> + +<p class="center">Reproduced by permission of the publishers, +Fredk. Warne & Co.</p></div> +<span class="pagenum"><a name="page33" id="page33"></a>page 33</span> + +<h2 style="margin-top: 3em;">RELIEF PRINTING</h2> + +<p style="line-height: 1%; margin-top: -0.5em;"> </p> +<p class="dropcap"><span class="dcap"> +I</span> +<b>N</b> order that illustrations may be incorporated in +the text, the blocks used must be in relief the same +as the type; a mixture of intaglio and relief is +impossible, for the whole surface must be level in order +to be inked by the rollers, which deposit the pigment +evenly, so that only one tone of colour—that of the ink—is +possible.</p> + +<p>Up to quite recent times wood cuts and engravings +were the only means available for text-illustrations, so +that this method may next be considered.*</p> + +<p class="note1"><span style="font-size: 1.2em;">*</span>See Treviranus, C.L.: <i>Die Anwendung des Holtzschnitts zur bildlichen +Darstellung von Pflanzen</i>. Leipzig, 1855.</p> + +<p><span style="font-size: 1.2em"><b>WOOD CUTS AND ENGRAVINGS.</b></span> The invention +of illustrating by means of wood blocks followed +closely on the heels of the use of moveable types +for printing. The Chinese were the first, as far as is +known, to use these methods of printing and illustration; +in the western world the first wood blocks date from the +beginning of the fifteenth century.</p> + +<p>All the earlier cuts were made, commonly on pear +wood, on the longitudinal face of the wood, in technical +language "on the plank," and seemingly, in many instances, +were made from drawings in ink. By cutting on +the plank, the craftsmen were enabled to make large +blocks, but were prohibited from doing anything more +than relatively simple and straightforward work. Such +blocks are known as wood cuts; wood engravings were +not made until the possibilities of a hard wood like box +carved upon the transverse section were discovered at a +much later date. This is, strictly speaking, wood engraving, +an art which almost entirely, if not quite, +superseded the older craft, on account of its great possibilities; +<span class="pagenum"><a name="page34" id="page34"></a>page 34</span> +indeed, wood engravers imitated metal engraving +so closely as to deceive many. But such work was enormously +laborious; for instance, in the case of a fishing +net, if the string were to be printed black, the engraver +would have to cut out hundreds of small diamond-shaped +pieces of wood in order that the string of the net should +be in relief. But few artists would do this of their own free +will, and generally such laborious work will only be +found in wood-engravings which were intended for the +reproduction of ink drawings or other kinds of pictures +where the lines, shading, etc., had to be faithfully copied. +This point may be illustrated by the accompanying cut +(Fig. 2), which was made by my friend Mr. Geoffrey +Oliver, who at the time was totally uninstructed in the +art and knew nothing of its literature. It will be seen that +he, quite unconsciously, treated his wood in the same +way as an engraver would his metal; the result, of +course, is just the opposite to metal engraving since the +printing of the wood block is the reverse to intaglio.</p> +<a name="fig2" id="fig2"></a> +<div class="figcenter" style="width: auto;"><a href="images/fig_2-1000.png"><img src="images/fig_2a-500.png" width="500" height="360" alt="Fig. 2" /></a> +<h4>Fig. 2.</h4></div> +<span class="pagenum"><a name="page35" id="page35"></a>page 35</span> + +<p>In fact, the cut illustrates the three fundamentals of +wood engraving; the white line made by cutting out +the wood so that no impression will be obtained when +printed; the white space which is similarly obtained; +and the black space, which is made by leaving the wood +untouched. It was, however, necessary to employ the +black line, otherwise the tape with which the two men—the +artist and his father—are measuring the trunk of the +tree would be invisible where it crosses the sky. In a word, +the little picture illustrates very nicely the legitimate use +of wood in the graphic arts.</p> + +<p>As already remarked, the majority of the earlier wood +cuts and engravings are reproductions of line drawings, +so that although we may admire and often marvel at the +technical ability of the engraver, the credit for what +artistic merit such illustrations may possess must, in the +majority of cases, go to the draughtsman.</p> + +<p>The work of the earlier wood engravers may be conveniently +studied in <i>A Lyttel Booke of Nonsense</i>, by R. +D., London, 1912. (See also the relevant works cited +under Literature, p. 94).</p> + +<p>Bewick, of course, is an outstanding example of an +artist who used wood engraving for illustrating natural +history; the methods he pursued may be studied in the +tailpiece on p. 11, which was printed from an electrotype +of the original block.</p> + +<p>Wood engraving, up to quite recent times, was the +method of reproducing text figures; not only for scientific +books and periodicals, but also for general literature +and journals.</p> + +<p>Much of this work is of outstanding excellence; for +scientific work the following may be studied:</p> + +<blockquote><p> +Duchartre: <i>Eléments de Botanique</i>. Paris, 1867. The +drawings were made by Riocreux and engraved by +Leblanc.</p> +<span class="pagenum"><a name="page36" id="page36"></a>page 36</span> + +<p>Baillon: <i>Histoire des Plantes</i>, Paris, 1887. This work +contains some beautiful wood engravings, reproductions +of drawings by Faguet.</p> + +<p>Bentham: <i>Handbook of the British Flora</i>, London, +1865. The engravings are from drawings by W. +H. Fitch.</p> + +<p>Deschanel: <i>Natural Philosophy</i>, London, 1890. The +engravings, many of which are of excellent quality, +are by Laplante, Rapine and others. In many cases, +notably in the representation of the rays of light +passing through lenses and also in the illustrations +of snow crystals, the use of the white line is admirably +demonstrated.</p> + +<p>Kerner: <i>Pflanzenleben</i>, Leipzig, 1888. This contains +some excellent engravings by Winkler and others.</p> + +<p>Le Maout et Decaisne; <i>Traité général de Botanique</i>, +Paris, 1876. This work contains splendid examples +by Riocreux and Steinheil (see Fig. 8).</p> + +<p>Oliver: <i>First Book of Indian Botany</i>, London, 1869. +This contains some characteristic work of W. H. +Fitch. +</p></blockquote> + +<p>It does not appear to be generally known that excellent +reproductions in colour may be obtained from wood +blocks by superposed printing in a manner comparable +to that followed in chromolithography although, of +course, in the present instance, the blocks are in relief +(Fig. 1).</p> + +<p>From the foregoing account it is obvious that the +engraving even of a small illustration, except it be in +mere outline, involves a considerable amount of labour; +in fact, if the subject were large it was usual to cut it up +into areas and distribute between several engravers, the +finished blocks finally being joined together to make the +block of the whole picture. Hence it is not surprising +<span class="pagenum"><a name="page37" id="page37"></a>page 37</span> +to find that when the photo-mechanical processes were +perfected, the older methods of reproduction were ousted +by the newer, more especially since they are much less +expensive; these, therefore, may next be considered.</p> + +<p><span style="font-size: 1.2em"><b>THE HALF TONE PROCESS.</b></span>—For the making of +a relief block by photo-mechanical means, the main +difficulty is the proper rendition of the tones intermediate +between black and white; this has been solved, at any +rate in part, by the discovery of the half-tone process.</p> + +<p>If an ordinary photographic negative be highly magnified, +it will be seen that the high lights, the low lights, +and the intermediate tones are made by the varying +density of the reduced silver. In the lighter parts the small +black particles are surrounded by colourless areas, whilst +in the dark regions small colourless patches are surrounded +by black areas owing to the closeness of the particles +of silver (Plate 5, Fig. 2).</p> + +<p>What is required, therefore, is a relief block which will +print a number of dots of equal density but of unequal +size. Vervasser illustrates the point in an ingenious way: +a plate, covered with a number of cones, is supposed to +be acted upon by light in such a way that the cones are +truncated in varying degrees according to intensity of +the light falling upon them. The section of such a plate +would therefore shew a curve (Fig. 3); now if the truncated +cones be brought down to one level and a print +taken from them, the high lights would be represented +by black dots surrounded by white areas and so on.</p> + +<a name="fig3" id="fig3"></a> +<div class="figcenter" style="width: auto;"><a href="images/fig_3-800.png"><img src="images/fig_3a-500.png" width="500" height="97" alt="Fig. 3" /></a> +<h4>Fig. 3</h4></div> + +<p>This illustrates the principle which obtains in the +<span class="pagenum"><a name="page38" id="page38"></a>page 38</span> +making of half-tones in which the image is made up of a +large number of dots varying in size but all equally dense, +so that when viewed from a suitable distance the dots +are individually invisible but compose to give gradations +of light and shade. In other words, the structure obtaining +in a photographic negative is, in a sense, realised by +optical chemical means, although the dots in a half-tone +block are much coarser than those in a negative (Plate 5, +Fig. 3).</p> + +<p>This result is obtained by interposing between the +diaphragm of the camera and the negative—for the half-tone +process is a photo-mechanical one—a glass screen +covered with intersecting engraved lines (Fig. 4). As a +matter of fact, each screen consists of two plates of glass +similarly ruled and cemented face to face so that the lines +intersect.</p> + +<a name="fig4" id="fig4"></a> +<div class="figcenter" style="width: auto;"><a href="images/fig_4-500.png"><img src="images/fig_4a-300.png" width="300" height="307" alt="Fig. 4" /></a> +<h4>Fig. 4</h4></div> + +<p>It may at first be thought that the effect of such a screen +placed in front of the negative would be to produce +merely a cross hatching on the reproduction; this, +however, is not the case; if the screen be placed in a +proper position relative to the negative and the size of +the diaphragm of the camera, the picture will be reproduced +in a series of dots of varying size.</p> + +<p>The optical and other reasons for this phenomenon +<span class="pagenum"><a name="page39" id="page39"></a>page 39</span> +must be sought elsewhere,* but the following brief consideration +will serve to illustrate what happens. The rays +of light which ultimately reach the sensitive plate are +acted upon by two lenses, that of the camera and the +meshes of the screen, each one of which acts as a lens on +the principle of the pin-hole camera. Each mesh, therefore, +brings the image of the diaphragm to a focus on the +negative, but the lens of the camera focusses the picture as +a whole, thus the amount of light falling on the different +pin-holes will vary in intensity, and hence the dots produced +will vary in size, for it is assumed, with good +reason, that each dot is built up from its centre and +radially expands according to the amount of light acting +upon it.</p> + +<p class="note1"><span style="font-size: 1.2em;">*</span>See Verfasser, <i>loc. cit.</i>, p. 94.</p> + +<p>It is obvious that the quality of the resulting picture +will depend, other things being equal, upon the coarseness +of the screen employed. Screens are ruled with lines +varying from 50 to 400 to the inch: the lower rulings +give very coarse reproductions, and are only used for +posters, whilst the higher rulings yield very fine impressions +and are employed only for the best work. It is +hardly necessary to remark that the finer the screen the +better must be the skill of the printer. To illustrate the +difference in the results obtained by the use of different +screens, the two figures on Plate 6 have been prepared; +both were made from the same negative, but for the +upper figure a 100-line screen was used, and for the lower +a 200-line screen. It will be observed that there is more +contrast in the former, and more detail in the latter. +Authors should therefore mention when sending in their +original pictures the qualities they require in the reproduction; +it must, however, be remembered that the +blocks made from the finer ruled screens will not print +satisfactorily except on more or less highly glazed paper, +<span class="pagenum"><a name="page40" id="page40"></a>page 40</span> +to the use of the "art" varieties of which there are objections +on æsthetic and other grounds.</p> + +<a name="plate6" id="plate6"></a> +<div class="figcenter" style="width: auto;"><a href="images/plate_6-1-1000.png"><img src="images/plate_6a-1-550.png" width="550" height="419" alt="Plate 6. 1" /></a> +<h4><span class="sc">Plate 6. - 1</span></h4></div> + +<div class="figcenter" style="width: auto;"><a href="images/plate_6-2-1000.png"><img src="images/plate_6a-2-550.png" width="550" height="425" alt="Plate 6. 2" /></a> +<h4><span class="sc">Plate 6. - 2</span></h4> +<p class="center" style="margin-top: -1em;">Half Tone reproduction of a photograph by Mr. W. Rowan.</p> + +<p class="center">Part of a shingle beach shewing plants of Sea Blite (<i>Suaeda +fruticosa</i>) and a ring plover's nest with four eggs.</p></div> + +<p>Before passing on it may be mentioned that screens +with patterns other than that represented in Fig. 4 are +sometimes employed; for instance, the wavy-line +screen gives the impression of coarse collotype.</p> + +<p>The preparation of the blocks may now be briefly +dealt with.</p> + +<p>A negative of the picture, using a screen suitable for +the purpose, is taken on a special dry gelatine plate +("process" plates) or on some other form of negative, +<i>e.g.</i>, wet collodion which is most commonly employed. +This negative requires very careful development in order +to get the dots right.</p> + +<p>From the negative a positive is made upon a copper +or zinc plate, suitably coated with a sensitive film. The +usual practice is to coat the polished metal plate with a +mixture of water, albumen, fish glue, ammonium bichromate, +chromic acid and ammonia; the plate is then +dried and, when cooled, exposed under the negative. +The action of the light on such a film, the essentials of +which are the albumen, the glue or gelatine and a chromate, +has already been described. The mixture becomes +more or less insoluble in water, according to the intensity +of the light falling upon it.</p> + +<p>The positive is now rinsed in water, and is sometimes +stained with an aniline dye in order to render the film more +visible. Next it is developed in a stream of water until +the surface of the metal is visible between the dots, the +last traces of the soluble gelatine being removed with +warm water. After drying, the plate is evenly heated over +a Bunsen burner until the dots of gelatine mixture turn +chocolate colour, when the plate is allowed to cool +gradually. This is known as burning in. The plate, if +necessary, is now touched up and the back, sides and +margins varnished in order to protect them from the +<span class="pagenum"><a name="page41" id="page41"></a>page 41</span> +acid: when the varnish is dry, the plate is etched in a +weak solution (about 2½ per cent.) of nitric acid if the +metal be zinc; if the plate be copper, it is usually etched +with a solution of iron perchloride.</p> + +<p>On taking a proof, there is almost certain to be a lack +of contrast, the plate is then fine etched, by which means +a considerable improvement can be made; and, by covering +certain parts with an acid-resisting substance +("stopping out"), it is possible to fine etch locally.</p> + +<p>Incidentally it may be mentioned that machine etching, +by which a fine spray of the etching fluid is distributed +over the plate, has recently come into vogue, for it is +claimed that the results print better and are in other +ways an improvement upon the older method.</p> + +<p>The plate may now pass through the hands of an engraver, +who removes any blemishes, as far as is possible, +improves the high lights, and so on; in fact, a skilful +engraver can improve the plate considerably.</p> + +<p>After the plate is trimmed, and the superfluous metal +cut out by means of a routing machine, it is firmly tacked +to a wooden mount, usually of oak, but sometimes of +mahogany, especially if the plate is large. In order to +obtain the best results, the printing, in a typographical +machine, should be done on highly calendered paper—so-called +"art" paper; in fact, this is absolutely essential +if a fine screen has been used; it is only the blocks made +with the coarser screens that will give fair prints on ordinary +paper. For this reason reproductions made by the +half-tone process are very generally treated as plates +unless the glazed paper is used throughout the book. +The process is used principally for the reproduction of +photographs, and for pencil or wash drawings.</p> + +<p>With regard to photographs, it has already been mentioned +that authors should send the negative or two or +three prints differently toned, in order that the operator +can choose the one most likely to give the best result.</p> +<span class="pagenum"><a name="page42" id="page42"></a>page 42</span> + +<p>It is sometimes difficult in a photograph of a landscape +to obtain a negative in which the particular feature it is +desired to represent—<i>e.g.</i>, in photographs of vegetation—stands +out with the requisite contrast. This is due to the +position of the sun at the time of exposure, or to the use +of ordinary plates. The remedy for the first is to take the +photograph when the proper light obtains; with regard +to the second, the use of colour correct plates, together +with a colour screen in front of the lens, will obviate the +defect. Since for scientific purposes the correct interpretation +of the various tones of the vegetation, for example, +may not be essential, variously coloured screens may be +used in order to emphasise a particular feature. For +instance, it will be noticed how well the bushes in Plate 7 +stand out. This effect was obtained by the use of a +panchromatic plate in conjunction with a red colour +screen.</p> + +<a name="plate7" id="plate7"></a> +<div class="figcenter" style="width: auto;"><a href="images/plate_7-800.png"><img src="images/plate_7a-400.png" width="400" height="388" alt="Plate 7" /></a> + <h4><span class="sc">Plate 7.</span>—Half Tone reproduction</h4> +<p class="center" style="margin-top: -1em;">of a photograph taken by Dr. Mees through a red screen.</p></div> + +<p>With regard to drawings in wash, charcoal or pencil, +in which there are half-tones; these are better drawn on +an enlarged scale, especially if the author is not a skilled +draughtsman, for improper gradations in shading and +other imperfections will not appear so noticeable in the +reduced reproduction. Originals should all be made in +one colour; in the case of wash drawings, diluted Indian +ink (really Chinese ink) will give excellent results.</p> + +<p>In making pencil drawings, a fairly stout hand-made +paper with not too much grain should be used. If the +drawing is to be of some size, the paper may be damped +and pasted by its edges on to the drawing board, it will +then be stretched quite flat and will not cockle when dry.</p> + +<p>The outline of the object may first be sketched in +lightly with a soft pencil and then the shading may be +proceeded with. To do this, broad-pointed soft pencils, +2 B, 3 B, or 4 B, should be used, and it is better generally +to work from the high lights to the shadows. To avoid +rubbing finished parts, the work should proceed from the +<span class="pagenum"><a name="page43" id="page43"></a>page 43</span> +top of the board downwards, especially in the case of +large drawings.</p> + +<p>In order to obtain a nice gradation and a more smooth +appearance—more especially when a very coarse paper +has been used—the work may be gone over with paper +stumps of appropriate size and softness, and, of course, +India rubber may be employed where it is desired to +reduce the density of the shading.</p> + +<p>When finished, the edges of the various parts may +appear woolly owing to the rubbing of the lead; this +may be cured by cleaning up the edges with a trimmed +piece of India rubber, but in so doing there is always a +risk of rubbing out part of the shading, especially if the +outline be at all intricate. If preferred, all the shaded +parts may be fixed by painting them over with a suitable +solution, gelatine for instance, paying particular attention +in following the correct outline. When dry, the application +of soft india-rubber will soon clean up the blurred +edges.</p> + +<p>If charcoal be used the same procedure may be +followed. Charcoal and pencil drawings should be fixed, +in order to prevent rubbing, before sending to the +block makers. A suitable fixative may be purchased or +one may be made by dissolving white resin in alcohol +and applying it to the paper by means of a scent +spray or an atomizer. A very good fixative may be +made by dissolving a little gelatine in hot water and +applying it whilst hot by means of a broad, flat +camel hair brush, or ordinary milk may be used in +a similar way. After the fixative has been put on, +the drawing should be pinned up by one corner—unless, +of course, it was pinned up before the fixative +was employed, which is the best way when the fixative +is an alcoholic solution—and allowed to dry; it may then +be placed under pressure in order to flatten it, for fixed +drawings generally shew a tendency to curl, especially +<span class="pagenum"><a name="page44" id="page44"></a>page 44</span> +when the preparation used for fixing has only been +applied to one surface of the paper.</p> + +<p>In making drawings for reproduction by means of the +half-tone process, there are a few general points to which +attention should be paid.</p> + +<p>It should be remembered that there is not infrequently +a tendency towards flatness in the reproduction; it is +therefore important that the originals should be "plucky," +and, on the whole, it is better to exaggerate with regard +to high light and shade, especially if there is much +modelling or perspective.</p> + +<p>Finally, with regard to lighting, it is better for the +majority in drawing their objects—solid objects in relief +are referred to—to use a more or less lateral illumination +and to represent only the high lights, shades and shadows +referable to this main direction of illumination. A high +relief will thus be obtained, and the effect will prove more +satisfactory than if minor sources of illumination are +unsuccessfully dealt with. This is especially important +in drawing complicated structures such as models of +vascular tissues, embryos, etc.</p> + +<p>In cases where many such figures are to occur on one +page, it is highly desirable that the lighting of each +should be from the same direction.</p> + +<p>The use of the half-tone block is now almost universal, +so that it is hardly necessary to mention examples, more +especially as they are hard to judge without seeing the +original picture. Those in the present book are all of a +high quality. Excellent examples will also be found in +Tansley's <i>Types of British Vegetation</i> (Cambridge, 1911) +and in the <i>Journal of the Royal Horticultural Society</i>.</p> + +<p>Proofs should be carefully compared with the originals, +particular attention being paid to the rendering of the +tones; as already remarked, fine etching will clear up a +block and will often prove a remedy to flatness.</p> +<span class="pagenum"><a name="page45" id="page45"></a>page 45</span> + +<p>An author will naturally consider whether a photograph +is to be reproduced by means of photogravure, collotype +or half-tone. It is impossible to lay down any laws on the +subject, but the following points should be considered.</p> + +<p>If it is essential to have the reproduction in the text, +a half-tone block must be used; it must, however, be +remembered that the paper used for the letterpress +may be very unsuited for the printing of half-tones. On +the other hand, if it be immaterial where the picture is +placed, then the relative merits of photogravure, collotype +and kindred processes and half-tone must be +weighed.</p> + +<p>Provided that expense need not be considered, photogravure +will, in the majority of cases, give the best results; +on the other hand, if this process is too costly, then +the choice lies between collotype and half-tone. The +latter method will often give a result with more contrast +as compared with collotype, whilst collotype will give a +truer interpretation of the tones.</p> + +<p>As has already been remarked, the best results with +half-tone blocks only are to be obtained by the employment +of a paper which seemingly has no lasting qualities; +it therefore follows that if the reproduction forms an +important record, the use of collotype is indicated, since +many varieties of good paper are available. As a general +rule photo-micrographs are best reproduced by collotype.</p> + +<p>In order that the respective qualities of these three +processes—photogravure, collotype and half-tone—may +be compared, Plates 8, 9, and 10 have been made from the +same photograph, a view taken by Dr. F. F. Blackman +of the Bouche d'Erquy, a salt marsh in Brittany, which +was selected chiefly on account of the large number of +tones it contains.</p> +<a name="plate8" id="plate8"></a> +<div class="figcenter" style="width: auto;"><a href="images/plate_8-700.png"><img src="images/plate_8a-340.png" width="340" height="495" alt="Plate 8" /></a> +<h4><span class="sc">Plate 8.</span> Photogravure</h4></div> +<a name="plate9" id="plate9"></a> +<div class="figcenter" style="width: auto;"><a href="images/plate_9-700.png"><img src="images/plate_9a-340.png" width="340" height="488" alt="Plate 9" /></a> +<h4><span class="sc">Plate 9.</span> Collotype</h4></div> +<a name="plate10" id="plate10"></a> +<div class="figcenter" style="width: auto;"><a href="images/plate_10-800.png"><img src="images/plate_10a-340.png" width="340" height="481" alt="Plate 10" /></a> +<h4><span class="sc">Plate 10.</span> Half Tone</h4></div> + +<p>These three plates are not entirely comparable, since +the heavy shadows in the right hand bottom portion of +the photogravure have been touched up by the engraver. +<span class="pagenum"><a name="page46" id="page46"></a>page 46</span> +This was not intended by the author, but the plate was +retained as it shews that directions regarding this point +should not be omitted when sending the drawing or +photograph to be reproduced. It also indicates that for +critical work, when an exact a facsimile as possible is +required, collotype should be used, for the plate cannot +be touched up.</p> + +<p>With regard to the reproduction of drawings shaded +by means of wash or pencil, the same remarks apply, +with the addition that if it be possible to express what +is desired by other means, suitable for reproduction by +line block, these latter should be employed. To illustrate +this point, Figures 5, 6, and Plate 11 have been inserted; +all illustrate the vascular skeleton of a fern (<i>Marattia +fraxinea</i>), the first one is in outline and the second is +shaded by lines of varying thickness; both of these are +reproduced by means of the line block, whilst the third +is a reproduction by half-tone of a pencil-shaded drawing. +In order to obtain a fair comparison, the half-tone is +reproduced as a plate, owing to the fact that it would +not print satisfactorily on the paper used for the +letterpress.</p> +<a name="fig6" id="fig6"></a> +<div class="figcenter" style="width: auto;"><a href="images/fig_5-800.png"><img src="images/fig_5a-400.png" width="400" height="496" alt="Fig. 5" /></a> +<h4>Fig. 5</h4></div> + +<div class="figcenter" style="width: auto;"><a href="images/fig_6-800.png"><img src="images/fig_6a-400.png" width="400" height="503" alt="Fif. 6" /></a> +<h4>Fig. 6</h4></div> +<a name="plate11" id="plate11"></a> +<div class="figcenter" style="width: auto;"><a href="images/plate_11-800.png"><img src="images/plate_11a-400.png" width="400" height="493" alt="Plate 11" /></a> +<h4><span class="sc">Plate 11</span></h4></div> + +<p><span style="font-size: 1.2em"><b>THE HALF-TONE THREE COLOUR PROCESS.</b></span>—This +process is much used for colour reproductions +of various subjects; and, in view of the fact that +the best results can only be obtained by the best photography, +the object should, if possible, be sent to specialists +for reproduction. In many cases, however, this is impossible, +<i>e.g.</i>, landscapes and animal and plant portraits +amidst their natural surroundings, so that the scientist, +if unable to make a water colour drawing, which will give +by far the best result, must make his own negatives.</p> + +<p>The first thing to do is to purchase a set of colour-filters, +adapted to the colour-correct plates to be used, +from firms who specialize in these matters, Messrs. +<span class="pagenum"><a name="page48" id="page48"></a>page 48</span> +Paget or Messrs. Wratten for instance, and from +them the inexperienced should obtain full information +regarding exposure, etc., for it is essential that the exposure +of the negatives should be correlated in order that +all may have the same tone-value.</p> + +<p>The colour-screens, blue, green and orange, are made +by dyeing gelatine with suitable stains; the films are stuck +on to perfectly plane glass and are mounted in frames. In +practice these screens are usually placed behind the lens, +in which case a special camera is necessary, or they may be +adapted to fit on to the front of the lens. In either case +the procedure is the same; three negatives are taken one +after the other through each colour filter, the exposure +being modified in order that the tones in each case may +be of equal value.</p> + +<p>There are thus obtained three negatives which, of +course, yield positives which look very different one from +the other. These prints may be sent to the block makers, +but it is better, on the whole, to send the negatives with +clear indications as to the colour of each.</p> + +<p>From each negative there is made by contact a transparency, +and from these positives there are prepared a +set of half-tone negatives from which are made the half-tone +blocks.</p> + +<p>The reproductions are made by superposed printing +of the three blocks, yellow being printed first, then red, +and finally blue (Plate 12).</p> + +<a name="plate12" id="plate12"></a> +<div class="figcenter" style="width: auto;"><a href="images/plate_12-800.png"><img src="images/plate_12a-300.png" width="300" height="465" alt="Plate 12" /></a> +<h4><span class="sc">Plate 12.</span>—Three Colour Half Tone.</h4></div> + +<p>As indicated above, it is hardly worth while to make +negatives for this process unless the operator is a really +skilful or at least an efficient photographer, and even then +the final product may prove unsatisfactory.</p> + +<p>Better results are generally to be obtained by sending +to the block maker a Lumiere colour photograph with +full instructions regarding any corrections in the colours +which may be necessary.</p> +<span class="pagenum"><a name="page49" id="page49"></a>page 49</span> + +<p>Examples:—</p> + +<p>Bateson: <i>Mendel's Principles of Heredity</i>, Cambridge, 1909. +Church: <i>Types of Floral Mechanism</i>, Oxford, 1908. +Seward: <i>Darwin and Modern Science</i>, Cambridge, 1909.</p> + +<p><span style="font-size: 1.2em"><b>PHOTO-MECHANICAL LINE BLOCKS.</b></span>—The +photo-mechanical line block, commonly known as a +zinco, is in a sense the lineal descendant of the wood +block. As a means of reproduction the possibilities of +line blocks are very great, for not only is it possible to +reproduce by their means all kinds of line drawings, but +also drawings in charcoal and crayon, provided they be +suitably executed on a proper grained surface. In fact, an +artist or draughtsman who has a thorough knowledge of +the process and its capabilities can obtain extraordinary +results. The process has the further advantage of being +both quick and inexpensive, a few hours only being required +to make the finished product.</p> + +<p>Their mode of manufacture is the same in principle +as for half-tone blocks; in the case of the latter, the +method known as the enamel process was described; in +the present instance a different procedure may be dealt +with.</p> + +<p>A photograph of the drawing is taken on a negative, +the wet collodion process being generally followed, although +dry process plates may be used.</p> + +<p>A highly polished zinc plate is sensitised with bichromate +of potash and gelatine, or by other means, and, when +dry, is exposed under the negative.</p> + +<p>The exposed metal plate is then taken into the dark +room and evenly, but thinly, coated with etching ink. +When the ink is dry, the plate is developed in water; +the unexposed gelatine, and with it, the ink, will come +away, its removal being helped by the judicious application +of a dabber of wet cotton wool.</p> + +<p>The plate may next be "rolled over" with an ink which +<span class="pagenum"><a name="page50" id="page50"></a>page 50</span> +will more stoutly resist the action of the acid than that +used in the first inking, but prior to this it is usual to soak +the plate in a mixture of gallic acid, phosphoric acid and +gum. This second rolling up must be carried out as if +the plate were for lithographic reproduction; and, when +dry, powdered resin may be applied, in order to make a +better acid-resist, as in the preparation of a lithographic +stone.</p> + +<p>The plate is now etched slightly in a weak solution of +nitric acid; it is then rinsed, dabbed dry and placed upon +a hot plate until the resin has stuck well to the ink. When +cool, the margins, sides and back are protected from the +action of the acid by means of a varnish and the plate is +given its first real etch, which is a very slight one. After +rinsing and drying, the plate is again heated until the ink +and resin have melted and flowed down the exposed sides +of the ridges of metal produced in the first etching. This +application of ink and resin must be repeated in order +that the exposed sides of the ridges may be well covered +with the acid-resist and so will not be undercut. The +plate is then given its second etch, and this is done +with a stronger acid, after which the sides of the lines +are again protected with resinous material in the +same way as before. The third etch follows, after +which the metal is thoroughly cleansed from all the +ink, etc.</p> + +<p>In order to smooth the shoulders of the lines, the plate +is given a finishing etch: the cleaned plate is warmed +and rolled up with hard etching ink; the metal is then +heated until the ink becomes glazed, and, when cool, is +placed in the acid bath for the requisite amount of time. +If necessary the plate, after cleaning, is touched up with +a graver, and the superfluous metal is cut away. Finally +it is mounted on a block of wood, and after the corners +and sides have been trimmed square, the block is ready +for the press.</p> +<span class="pagenum"><a name="page51" id="page51"></a>page 51</span> + +<p>To illustrate the enormous improvement which may +result from the block passing through the hands of a +skilful engraver, two line blocks of a wood engraving by +Riocreux (see p. 36) have been prepared. Fig. 7 is the +impression given by the block as ordinarily turned out, +whilst Fig. 8 is a precisely similar block which has been +worked up by an engraver.</p> + +<a name="fig7" id="fig7"></a> +<div class="figcenter" style="width: auto;"><a href="images/fig_7-800.png"><img src="images/fig_7a-400.png" width="400" height="384" alt="Fig. 7" /></a> +<h4>Fig. 7</h4></div> + +<a name="fig8" id="fig8"></a> +<div class="figcenter" style="width: auto;"><a href="images/fig_8-800.png"><img src="images/fig_8a-400.png" width="400" height="384" alt="Fig. 8" /></a> +<h4>Fig. 8</h4></div> + +<p>There are several other methods of making the blocks, +but the principles are the same as in the foregoing process.</p> + +<p>In examining the proofs it must be remembered that +deletions are not the only alterations that can be made in +the finished block; not only can lines be cut away, or +their character altered by removing part of the metal +from them, but additions can be made in reason. For instance, +lines can be added across open spaces, and if part +of the printing surface has been accidentally removed in +cutting away the superfluous metal, the damage can be +made good by building up with solder and working on +this with the graver. If, however, the additions required +are at all extensive or complicated, it is better to have a +new block made.</p> + +<p>Inasmuch as scientific illustrations are to describe and +explain definite facts, the drawings must needs be materialistic +rather than suggestive; in other words, a more +or less conventional system must be employed.</p> + +<p>In making their drawings for reproduction by line +blocks, authors have at their disposal the black line, the +white line, the black space, the white space, the black +dot and the white dot, all of which may be combined in +various ways. No tones, other than black and white, are +available; if it be desired to represent half-tones, they +must be rendered by the above-mentioned means.</p> + +<p>In the majority of cases the originals should be made with +black ink on white Bristol board or smooth white paper; +ordinary lead pencil drawings on smooth paper are useless, +and lead pencil, black crayon or charcoal in combination +<span class="pagenum"><a name="page52" id="page52"></a>page 52</span> +with grained paper or board should not be employed +unless the draughtsman has the requisite skill and knows +exactly the limitations of the line block. For all ordinary +folk black ink and Bristol board cannot be improved upon.</p> + +<p>The drawing may be made first with a soft lead pencil, +using the camera lucida or other optical aids to correct +delineation. The pencil lines are then gone over with ink; +for this purpose a good black ink is necessary. Wolff's +Indian ink, Higgins' waterproof ink and Steuber's waterproof +drawing ink are highly satisfactory, and there are +many others. With regard to pens, a suitable implement is +all-important; Gillott's lithographic pens and Brandauer's +No. 515 are recommended. For straight lines of an even +thickness a ruling pen is very useful, and these may be obtained +fitted with an adjustment which enables the worker +to rule a line of a definite thickness, <i>e.g.</i>, .5 mm. and so on.</p> + +<p>All drawings should be made larger than it is intended +<span class="pagenum"><a name="page53" id="page53"></a>page 53</span> +the reproduction to be, for slight inaccuracies, ragged +lines, and other blemishes will thus appear less obvious. +This drawing on a large scale is often a stumbling block, +because the work appears too open and the draughtsman +is tempted to put in too much; this must be avoided, +else the crowded lines may join together in the reduced +reproduction. Also it must be remembered not to draw +too finely, else the work in parts may disappear entirely +in the reproduction. In drawing on an enlarged scale a +certain amount of exaggeration may be employed, in order +that when reduced the drawing may not be quite spiritless.</p> + +<p>When representing a solid object, such as a plant or an +animal, to shew the external morphology, it is to be borne +in mind that form is the main thing to represent, and this +can be expressed by outline drawing alone. In fact, more +or less primitive methods must be employed, and better +models cannot be followed than the best wood cuts.</p> +<span class="pagenum"><a name="page54" id="page54"></a>page 54</span> + +<div class="figcenter" style="width: auto;"><a href="images/fig_9-800.png"><img src="images/fig_9a-400.png" width="400" height="361" alt="Fig. 9" /></a> +<h4>Fig. 9. The Lesser Celandine (<i>Ranunculus Ficaria</i>).</h4> +<p class="center" style="margin-top: -1em;">By R. G. Hatton. (From Hatton's <i>Craftsman's Handbook</i>).</p></div> + +<a name="fig10" id="fig10"></a> +<div class="figcenter" style="width: auto;"><a href="images/fig_10-800.png"><img src="images/fig_10a-400.png" width="400" height="447" alt="Fig. 10" /></a> +<h4>Fig. 10. The Lesser Celandine. After Fuchs.</h4> +<p class="center" style="margin-top: -1em;">(From Hatton's <i>Craftsman's Handbook</i>.)</p></div> + +<span class="pagenum"><a name="page55" id="page55"></a>page 55</span> + +<p>An examination of figures 10 and 12 will shew that +Fuchs* attained his object by simple outline drawings; +he never employed local colour, and shading he used +very sparsely indeed, and then only to give expression +to the form of some thick part. Fuchs's celandine (Fig. +10) should be compared with the drawing of the same +plant (Fig. 9) by R. G. Hatton.</p> + +<p class="note1"><span style="font-size: 1.2em;">*</span>The methods followed by the illustrators of the Herbals may be +conveniently studied in Hatton's "The Craftsman's Plant Book," London, 1909, and Arber's +"Herbals," Cambridge, 1912.</p> + +<a name="fig11" id="fig11"></a> +<div class="figcenter" style="width: auto;"><a href="images/fig_11-800.png"><img src="images/fig_11a-290.png" width="280" height="491" alt="Fig. 11" /></a> + <h4>Fig. 11. The Apple (<i>Pyrus Malus</i>). After Matthiolus.</h4> +<p class="center" style="margin-top: -1em;">(From Hatton's <i>Craftsman's Handbook</i>).</p></div> + +<p>The methods of Matthiolus (Figs. 11 and 13) were +somewhat more advanced, for he used shading not only +to express form but also to give a certain amount of +<span class="pagenum"><a name="page56" id="page56"></a>page 56</span> +relief. It will be noticed that he shaded by lines which +followed the moulding of the parts.</p> + +<p>The work of Riocreux (Fig. 8) should also be studied; +it will be observed that he managed to get a very high +relief in his drawings by the simple means of straight +or curved lines, according to the shape of the part, of +varying thicknesses.</p> +<a name="fig13" id="fig13"></a> +<div class="figcenter" style="width: auto;"><a href="images/fig_12-800.png"><img src="images/fig_12a-320.png" width="320" height="484" alt="Fig. 12" /></a> + <h4>Fig. 12. Charlock (<i>Brassica Sinapis</i>). After Fuchs.</h4> +<p class="center" style="margin-top: -1em;">(From Hatton's <i>Craftsman's Handbook</i>)</p></div> + +<p>There is no necessity for keeping all the lines of even +thickness. For instance, provided the character of the +form is not altered, the outline on the shaded side may +<span class="pagenum"><a name="page57" id="page57"></a>page 57</span> +be made thicker than on the illuminated side; also distance +can be indicated by the use of thinner lines, for +these, although really black, will give the impression of +greyness. Then again, a line may be drawn with local +increases and decreases in thickness, as in ordinary +writing, and such lines drawn by a skilled hand can be +made to express a marvellous amount of modelling.</p> + +<div class="figcenter" style="width: auto;"><a href="images/fig_13-800.png"><img src="images/fig_13a-270.png" width="270" height="482" alt="Fig. 13" /></a> + <h4>Fig. 13. Sea Lavender (<i>Statice Limonium</i>). After Matthiolus.</h4> +<p class="center" style="margin-top: -1em;">(From Hatton's <i>Craftsman's Handbook</i>.)</p></div> + +<p>The draughtsman, however, is not restricted to lines; +any marks which can be made with a pen and black ink +may be employed, provided they be sufficiently firm and +large.</p> +<span class="pagenum"><a name="page58" id="page58"></a>page 58</span> + +<p>The accompanying figure (14) which is a reduction +of an illustration in Church's <i>Floral Mechanisms</i>, illustrates +the use of lines of varying lengths for shading.</p> +<a name="fig14" id="fig14"></a> +<div class="figcenter" style="width: auto;"><a href="images/fig_14-800.png"><img src="images/fig_14a-380.png" width="380" height="484" alt="Fig. 14" /></a> +<h4>Fig. 14. <i>Viola odorata</i>: Floral morphology.</h4> +<p class="center" style="margin-top: -1em;">A reduction of a figure in Church's <i>Floral Mechanisms</i>.</p></div> + +<p>In shading, the effect of shadow may be obtained by +increasing the thickness of the lines, but they must not +be drawn too closely together; on the other hand, the +<span class="pagenum"><a name="page59" id="page59"></a>page 59</span> +lighter parts can be represented by thinner lines placed +further and further apart, and the lightest parts by the +white of the paper. +Cross hatching may also be employed +(see Fig. 15), but the crossed lines must not be +too close together, for otherwise they +will tend to thicken in the making of +the block and so will print too black.</p> +<a name="fig15" id="fig15"></a> +<div class="figleft" style="width: auto; margin-top: -1em;"><a href="images/fig_15-400.png"><img src="images/fig_15a-85.png" width="85" height="310" alt="Fig. 15" /></a> +<h4>Fig. 15. A Seedling<br /> of <i>Abronia villosa</i>.</h4></div> + +<p>For very delicate shading and +tinting, stipple may be employed, +but the dots must be quite definite, +sufficiently large to stand reduction, +and not too close together (Figs. 18, +28c, and 32). A particularly good +example of this method will be +found in Butler's paper on <i>Allomyces</i> +in the Annals of Botany, 1911, vol. +25. Dots have also been employed +in Fig. 28c (p. 69).</p> + +<p>With regard to local colour; this +may be indicated by shading, by a +white space, or by a black space.</p> + +<p>Hitherto, drawing with black ink on white paper +alone has been considered, but the reverse is equally +available; much can be expressed by drawing with white +ink on black paper.</p> + +<p>Drawing in white upon a black ground is not frequently +attempted, but an excellent example by Miss Janet +Robertson is shewn in figure 16, which is well worthy of +study, since it illustrates to a nicety some of the means +at the disposal of the draughtsman for line blocks. The +black surface is best obtained by the use of a waterproof +Indian ink applied with a brush to a white surface, the +drawing being made with a dense white ink, using a pen +or a brush. The white ink may be made by diluting any +good opaque white water-colour paint, or process white +may be used. The composition of this should be zinc +<span class="pagenum"><a name="page60" id="page60"></a>page 60</span> +oxide or baryta, for these do not darken with age; the +author once used for this purpose a white pigment which +proved excellent at the time; the drawings, however, +subsequently turned dark brown owing to the fact that +the basis of the paint was apparently a compound of silver.</p> +<p style="clear: both;"> </p> + +<a name="fig16" id="fig16"></a> +<div class="figcenter" style="width: auto;"><a href="images/fig_16-800.png"><img src="images/fig_16a-350.png" width="350" height="495" alt="Fig.16" /></a> + <h4>Fig. 16. <i>Neuropteris Heterophylla</i>.</h4> +<p class="center" style="margin-top: -1em;">A line reproduction of a drawing by Miss Janet Robertson.</p></div> +<span class="pagenum"><a name="page61" id="page61"></a>page 61</span> +<p>The top part of the drawing (Fig. 16), shewing the +general morphology 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.</p> +<a name="fig17" id="fig17"></a> +<div class="figcenter" style="width: auto;"><a href="images/fig_17-800.png"><img src="images/fig_17a-400.png" width="400" height="396" alt="Fig. 17" /></a> +<h4>Fig. 17. <i>Fucus volubilis</i>, var. <i>Flexuosus</i>, a seaweed.</h4> +<p class="center" style="margin-top: -1em;">(From a drawing by Miss Baker.)</p></div> +<span class="pagenum"><a name="page62" id="page62"></a>page 62</span> +<p>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.</p> + +<p>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.</p> +<a name="fig18" id="fig18"></a> +<div class="figcenter" style="width: auto;"><a href="images/fig_18-800.png"><img src="images/fig_18a-360.png" width="360" height="495" alt="Fig. 18" /></a> +<h4>Fig. 18. The Larkspur (<i>Delphinium ajacis</i>).</h4> +<p class="center" style="margin-top: -1em;">By R. G. Hatton. (Hatton, <i>Craftsman's Handbook</i>.)</p></div> + +<span class="pagenum"><a name="page63" id="page63"></a>page 63</span> + +<table align="center" width="500px" summary="Fig. 19 - Fig. 21" border="0"> +<tr> +<td class="left" width="250px"><br /><a href="images/fig_19-800.png"><img src="images/fig_19a-200.png" width="200" height="272" alt="Fig. 19" border="0" /></a> +<h4>Fig. 19.</h4> +<p style="margin-top: -1em;">Hollyhock (<i>Althaea rosea</i>).<br /> +By R. G. Hatton.<br /> +(Hatton, <i>Craftsman's Handbook</i>.)</p> +</td> +<td class="left" rowspan="2" width="250px" valign="bottom"><br /><a name="fig21" id="fig21"></a> +<a href="images/fig_21-500.png"><img src="images/fig_21a-200.png" width="200" height="583" alt="Fig. 21" border="0" /></a> +<h4>Fig. 21.</h4> +<p style="margin-top: -1em;">A Seedling of <br /><i>Bruguiera gymnorhiza</i>, +a mangrove. <br />Drawn by Mrs. F. E. Fritsch. <br />(Tansley and Fritsch, <br /><i>New Phytologist</i>, 1905, vol. 4.)<br /><br /></p></td> +</tr> +<tr> +<td class="left" ><a name="fig20" id="fig20"></a> +<a href="images/fig_20-700.png"><img src="images/fig_20a-200.png" width="200" height="271" alt="Fig. 20" border="0" /></a> +<h4>Fig. 20.</h4> +<p style="margin-top: -1em;">A Liverwort (<i>Lepidozia reptans</i>).<br /> +(Evans, <i>Annals of Botany</i>,<br /> 1912, vol. 26.)<br /><br /></p></td> +</tr> +</table> + +<span class="pagenum"><a name="page64" id="page64"></a>page 64</span> + +<div class="figcenter" style="width: auto;"><a href="images/fig_22-800.png"><img src="images/fig_22a-360.png" width="360" height="492" alt="Fig. 22" /></a> +<h4>Fig. 22</h4> +<p class="center" style="margin-top: -1em;">A diagrammatic sketch by Mrs. F. E. Fritsch +of <i>Rhizophora conjugata</i>, a mangrove. <br />(Tansley +and Fritsch, <i>New Phytologist</i>, 1905, vol. 4.)</p></div> +<span class="pagenum"><a name="page65" id="page65"></a>page 65</span> + +<a name="fig23" id="fig23"></a> +<div class="figcenter" style="width: auto;"><a href="images/fig_23-800.png"><img src="images/fig_23a-390.png" width="390" height="488" alt="Fig. 23" /></a> +<h4>Fig. 23</h4> +<p class="center" style="margin-top: -1em;">A shoot of <i>Acanthus ilicifolia</i>, a mangrove. Drawn by +Mrs. F. E. Fritsch. <br />(Tansley and Fritsch, <i>New Phytologist</i>, +1905, vol. 4.)</p></div> + +<a name="fig24" id="fig24"></a> +<div class="figcenter" style="width: auto;"><a href="images/fig_24-800.png"><img src="images/fig_24a-400.png" width="400" height="285" alt="Fig. 24" /></a> +<h4>Fig. 24</h4> +<p class="center" style="margin-top: -1em;">A longitudinal section of a fossil seed, <i>Conostoma oblongum</i>.<br /> +Drawn by Dr. E. J. Salisbury. (Oliver and Salisbury, <i>Annals of Botany</i>, 1911, vol. 25.)</p></div> +<span class="pagenum"><a name="page66" id="page66"></a>page 66</span> + +<div class="figcenter" style="width: auto;"><a href="images/fig_25-1000.png"><img src="images/fig_25a-600.png" width="600" height="300" alt="Fig. 25" /></a> +<h4>Fig. 25</h4> +<p class="center" style="margin-top: -1em;">The Meadowsweet (<i>Spiraea ulmaria</i>), shewing four years' growth. +(Yapp, <i>Annals of Botany</i>, 1912, vol. 26.).</p></div> +<span class="pagenum"><a name="page67" id="page67"></a>page 67</span> + +<a name="fig26" id="fig26"></a> +<div class="figcenter" style="width: auto;"><a href="images/fig_26-800.png"><img src="images/fig_26a-400.png" width="400" height="493" alt="Fig. 26" /></a> +<h4>Fig. 26. The Chesil Bank.</h4> +<p class="center" style="margin-top: -1em;">(Oliver, <i>New Phytologist</i>, 1912, vol. 11.)</p></div> + +<h2 style="margin-top: 3em;">THE DRAWING OF MICROSCOPIC DETAILS.</h2> + +<p>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.</p> +<span class="pagenum"><a name="page68" id="page68"></a>page 68</span> + +<p>For demonstration purposes, transverse sections of +plant-structures may first be taken.</p> + +<p>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, <i>e.g.</i>, 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 lamellæ of the wood-elements +are represented by black lines.</p> + +<a name="fig27" id="fig27"></a> +<div class="figcenter" style="width: auto;"><a href="images/fig_27-800.png"><img src="images/fig_27a-500.png" width="500" height="207" alt="Fig. 27" /></a> +<h4>Fig. 27.</h4> +<p class="center" style="margin-top: -1em;">(From Butler's paper on Gummosis of <i>Prunus</i> and<br /> +<i>Citrus</i>. <i>Annals of Botany</i>, 1911, Vol. 25).</p></div> + +<p>This is a particularly good drawing, but, unfortunately, +it has been over reduced.</p> + +<p>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 <i>a</i>. If preferred, such thick-walled +<span class="pagenum"><a name="page69" id="page69"></a>page 69</span> +elements may be entirely represented by thick +black lines as in Figure 28<i>b</i>, and when such cells are +relatively few in number, this method has much to +recommend it since a greater relief is obtained.</p> + +<a name="fig28" id="fig28"></a> +<table align="center" summary="Fig. 28" border="0"> +<tr> + <td colspan="2" width="500px"> +<a href="images/fig_28-800.png"><img src="images/fig_28a-1-500.png" width="500" height="280" alt="Fig. 28" border="0" /></a> + </td> +</tr> +<tr> + <td width="250px"> +<a href="images/fig_28-800.png"><img src="images/fig_28a-2-250.png" width="250" height="280" alt="Fig. 28" border="0" /></a> + + </td> + <td class="left" style="padding-left: 2em;" width="250px"> +<h4>Fig. 28.</h4> +<p>A transverse section to shew<br /> +the vascular cylinder of the<br /> +root of the spinach, <i>c</i> is<br /> +somewhat older than <i>a</i> and <i>b</i>.</p> + </td> +</tr> +</table> +<br clear="all" /> + +<p>Finally, an attempt may be made to draw in a more +detailed fashion as in Figure 28<i>c</i>. Here the thickness of +the cells of the wood is represented by broad black lines, +the middle lamellæ 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 +<span class="pagenum"><a name="page70" id="page70"></a>page 70</span> +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.</p> + +<p>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.</p> + +<a name="fig29" id="fig29"></a> +<div class="figcenter" style="width: auto;"><a href="images/fig_29-600.png"><img src="images/fig_29a-300.png" width="300" height="359" alt="" /></a> +<h4>Fig. 29</h4></div> + +<p>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.*</p> + +<p class="note1"><span style="font-size: 1.2em;">*</span>Many similar examples will be found in Ridewood's memoir <i>On the +Cranial Osteology of the Clupeoid Fishes</i>, Proc. Zoo. Soc., Lond., 1904, vol. 11, p. +448.</p> +<span class="pagenum"><a name="page71" id="page71"></a>page 71</span> + +<a name="fig30" id="fig30"></a> +<div class="figcenter" style="width: auto;"><a href="images/fig_30-800.png"><img src="images/fig_30a-400.png" width="400" height="347" alt="" /></a> +<h4>Fig. 30</h4></div> + +<p>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).</p> + +<a name="fig31" id="fig31"></a> +<div class="figcenter" style="width: auto;"><a href="images/fig_31-500.png"><img src="images/fig_31a-230.png" width="230" height="472" alt="Fig. 31" /></a> +<h4>Fig. 31. After a water-colour design by Miss Winifred Pearse.</h4></div> +<span class="pagenum"><a name="page72" id="page72"></a>page 72</span> + +<p><span style="font-size: 1.2em"><b>THE DRAWING OF DIAGRAMS AND +APPARATUS.</b></span> Much valuable information may be +conveyed by diagrams; in fact, these could be used +more freely than they are.</p> + +<a name="fig32" id="fig32"></a> +<div class="figcenter" style="width: auto;"><a href="images/fig_32-800.png"><img src="images/fig_32a-450.png" width="450" height="289" alt="Fig. 32" /></a> +<h4>Fig. 32</h4></div> + +<p>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 +<span class="pagenum"><a name="page73" id="page73"></a>page 73</span> +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).</p> + +<a name="fig33" id="fig33"></a> +<div class="figcenter" style="width: auto;"><a href="images/fig_33-600.png"><img src="images/fig_33a-300.png" width="300" height="327" alt="Fig. 33" /></a> + <h4>Fig. 33. A diagram by Mr. E. Lee.</h4> +<p class="center" style="margin-top: -1em;">(<i>Annals of Botany</i>, 1911, vol. 25.)</p></div> + +<a name="fig34" id="fig34"></a> +<div class="figcenter" style="width: auto;"><a href="images/fig_34-800.png"><img src="images/fig_34a-500.png" width="500" height="339" alt="Fig. 34" /></a> +<h4>Fig. 34</h4> +<p class="center" style="margin-top: -1em;">A Diagram from the <i>Annals of Botany</i>, 1912, Vol. 26.</p></div> + +<p>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 <i>Gills of Lamellibranchiata</i> (Transactions of the +Royal Society of London, B. vol. 195, 1903). The +shading employed was either done by the draughtsman +(at <i>ch</i> and in the cells with irregularly arranged dots), +or else was put on the block during its manufacture +(<i>af</i>). If a lens be used, the difference will at once be +obvious.</p> + +<p>The finished drawing should be bold and neat, and +all lettering should be very clear. If several figures are +<span class="pagenum"><a name="page74" id="page74"></a>page 74</span> +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."</p> + +<p>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 <i>Natural Philosophy</i> (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.</p> +<span class="pagenum"><a name="page75" id="page75"></a>page 75</span> + +<p>A study of a good example is infinitely better than a +written description, wherefore Figure 35 has been inserted.</p> + +<a name="fig35" id="fig35"></a> +<div class="figcenter" style="width: auto;"><a href="images/fig_35-1000.png"><img src="images/fig_35a-550.png" width="550" height="494" alt="Fig. 35" /></a> +<h4>Fig. 35</h4></div> +<span class="pagenum"><a name="page76" id="page76"></a>page 76</span> + +<p>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.</p> + +<p>These conventionalities need not all be followed; for +instance, rubber connexions may be indicated by broad +black lines and wood by diagonal shading.</p> + +<p>The drawing should be very bold and the different +parts clearly and freely indicated by writing or "printing."</p> + +<p><span style="font-size: 1.2em"><b>THE DRAWING OF MAPS.</b></span> 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.</p> + +<p>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.</p> + +<p>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.</p> +<span class="pagenum"><a name="page77" id="page77"></a>page 77</span> + +<table align="center" summary="Fig. 28" border="0"> +<tr> + <td colspan="2" width="500px"> +<a href="images/fig_36-800.png"><img src="images/fig_36-1-500.png" width="500" height="250" alt="Fig. 36-1" border="0" /></a> + </td> +</tr> +<tr> + <td width="250px"> +<a href="images/fig_36-800.png"><img src="images/fig_36-2-250.png" width="250" height="250" alt="Fig. 36-2" border="0" /></a> + </td> + <td class="left" style="padding-left: 0.5em; padding-right: 0.5em;" width="250px"> + <h4>Fig. 36</h4> +<p>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.</p> + + </td> +</tr> +</table> +<br clear="all" /> + +<p>The indication of hills is always a problem; the most +satisfactory way is by the drawing of contours (Figure +36<i>a</i>), 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<i>b</i>) 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 +<span class="pagenum"><a name="page78" id="page78"></a>page 78</span> +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<i>c</i>). 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."</p> + +<p>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.</p> + +<p>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, <i>e.g.</i>, 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.</p> + +<p>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.</p> + +<p>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 +<span class="pagenum"><a name="page79" id="page79"></a>page 79</span> +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.</p> + +<p>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.</p> + +<p>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 +(<i>Annals of Botany</i>, 1911, Vol. 25).</p> + +<a name="fig37" id="fig37"></a> +<div class="figcenter" style="width: auto;"><a href="images/fig_37-800.png"><img src="images/fig_37a-310.png" width="310" height="497" alt="Fig. 37" /></a> +<h4>Figure 37. A Map of the Fenland by Prof. Yapp.</h4> +<p class="center" style="margin-top: -1em;">(<i>New Phytologist</i>, 1908, Vol. 7)</p></div> + +<p><span style="font-size: 1.2em"><b>GRAPHS OR CURVES.</b></span> 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 +<span class="pagenum"><a name="page81" id="page81"></a>page 81</span> +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 <br />the thick continuous line <span style="font-weight: bolder; font-size: 2em;">——</span>, +<br />the thin continuous line ————, <br />dashes either thick or +thin <span style="font-weight: bolder; font-size: 2em;">— — —</span>, or —— —— ——, +<br />dots · · · · · · ·, <br />and finally +combinations of dots and dashes — · — · — ·</p> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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 +<span class="pagenum"><a name="page82" id="page82"></a>page 82</span> +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.*</p> + +<p class="note2"><span style="font-size: 1.2em;">*</span>The chief disadvantage of iodine solution is its slowness of action; the +following methods are much quicker.</p> + +<p class="note1a">(<i>a</i>) 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.</p> + +<p class="note1b">(<i>b</i>) 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.</p> + +<p>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.</p> + +<p>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.</p> +<span class="pagenum"><a name="page83" id="page83"></a>page 83</span> + +<p>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.</p> + +<p>It must also be remembered that a reduction of, say, +½ linear means that the reproduction will be a quarter the +area of the original.</p> + +<p>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 ——————2½"—————.</p> + +<p>The question arises as to when line drawings for reproduction +by the zinc block should be employed.</p> + +<p>The answer is, Whenever possible.</p> + +<p>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.</p> + +<p>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 +<span class="pagenum"><a name="page84" id="page84"></a>page 84</span> +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 2½d. 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.</p> + +<p><span style="font-size: 1.2em"><b>THE SWELLED GELATINE PROCESS.</b></span> From +the foregoing account of the line-block it may, perhaps, +be thought that a drawing shewing the finest detail +cannot be reproduced in the text by a relief block made +by photo-chemical means. This is not the case; the +swelled gelatine process is such that at its best the very +finest work can be so reproduced. The method is not +extensively used, chiefly owing to the remarkable amount +of skill required to produce the best results and to the +facts that the blocks take longer to make and are more +expensive than the ordinary line block. This, however, +should not militate against its use, for the increased cost +is but very little, and the longer time in making, say two +days, should not be of any consequence in a monthly or +quarterly periodical. The great point in its favour is its +great fidelity as compared with the ordinary photo-chemical +relief blocks: for instance, a close cross-hatching +reproduced by a line block will often come out +as a series of white dots owing to the fact that at the +points of intersection the black lines tend to thicken; +hence, on printing, the white spaces, instead of being +sharply cut and diamond-shaped, are rounded. This +will not occur in a good block made by the swelled +gelatine method. Further, the process does not restrict +the draughtsman to dead black ink; the drawings may +be made in pencil, crayon, or in ordinary writing ink: +it is even claimed that wash drawings and photographs +<span class="pagenum"><a name="page86" id="page86"></a>page 86</span> +can be reproduced satisfactorily by this method. In the +case of pencil drawings, the best results will be given +when the surface of the paper used by the draughtsman +is slightly rough; a pencil drawing on Bristol board, for +example, will not be so well reproduced as one on ordinary +smooth drawing paper. In brief, the process +is as follows: a photographic negative of the drawing is +made, and under it is exposed a bichromate gelatine +plate. This plate is then developed in water. As already +described, the gelatine will swell up in proportion to +the amount of light to which it was exposed. The +"positive" thus obtained will be in relief, the high +lights being at a higher level than the shadows. A wax +mould of the gelatine positive is then taken, covered +with a thin layer of plumbago and electrically covered +with copper. The "casting" so obtained is built up +with metal and then mounted on wood in the same way +as a zinco or a half-tone. The capabilities of the process +may be judged by a study of Fig. 38, which is an +extremely faithful reproduction of a lithograph, by S. +Prout, by the swelled gelatine process.</p> +<a name="fig38" id="fig38"></a> +<div class="figcenter" style="width: auto;"><a href="images/fig_38-1000.png"><img src="images/fig_38a-550.png" width="550" height="418" alt="Fig. 38" /></a> +<h4>Fig. 38. A Lithograph by S. Prout reproduced by the swelled +gelatine process.</h4></div> + +<a name="fig86" id="fig86"></a> +<div class="figcenter" style="width: auto;"><a href="images/tailpiece_p86-800.png"><img src="images/tailpiece_p86-400.png" width="400" height="212" alt="tailpiece" /></a> +</div> +<span class="pagenum"><a name="page87" id="page87"></a>page 87</span> + +<h2>COST</h2> + +<span class="pagenum"><a name="page89" id="page89"></a>page 89</span> + +<h3>RELATIVE COST OF BLOCKS AND PLATES</h3> + +<p style="line-height: 1%; margin-top: -0.5em;"> </p> +<p class="dropcap"><span class="dcap"> +T</span> +<b>HE</b> question of cost is one of very great difficulty; +in all probability no two firms will agree in their +quotations for different kinds of work, and the +reason for this lies in the large number of factors involved, +many of which are very difficult to compute exactly. With +respect to line engravings, etching, mezzotint, wood cuts +and wood engravings, it is impossible to give any idea of +the cost. It depends entirely on the complexity of the +subject and the artist employed.</p> + +<p>As regards lithographic processes for reproduction in +one colour the cost varies with the nature of the work. +If an artist be commissioned to make an autolithograph, +the fee would be agreed upon beforehand. Photolithography +and collotype, on the other hand, are processes +which do not require the hand of an artist, and these +methods of reproduction are relatively inexpensive. The +price quoted by the lithographer or collotyper is for +printing so many copies, hence the relative cost per copy +depends upon the run and on the quality of the paper +used. Lithography is cheaper than collotype; but if +several illustrations are sent at the same time to be reproduced +by collotype, the cost for each would be less than +if sent separately.</p> + +<p>In chromolithography a separate stone is necessary +for each colour, hence the cost depends upon the number +of stones used, and as several may be necessary to obtain +a first-rate reproduction, it is obvious that the process +may prove very expensive.</p> + +<p>Turning to photomechanical processes, the prices vary +according to the grade of work required—the best possible, +<span class="pagenum"><a name="page90" id="page90"></a>page 90</span> +good, and, lastly, cheap work. By best possible is meant +the best that can be made under existing conditions, the +price being immaterial; in good work the cost will be a +limiting but not a preponderating factor, hence the work +will be open to criticism; finally, in cheap work, the price +is all important, so that the result is a block or a plate +which will print well but which must not be criticized as +regards its being a faithful reproduction of the original.</p> + +<p>It is obvious that in the last two cases the quality of the +work will depend upon the agreed price, whilst in the +first case the cost will depend on the amount of time and +skill required.</p> + +<p>It is obvious, therefore, that a comparison of cost cannot +be made between these grades; it is, however, possible +to draw up a scale of relative cost of the processes under +consideration for work of the same grade. In the table +given below, A represents the best possible work, B indicates +good work, and C stands for cheap work. Since +the line block is the least expensive it is taken as the unit +of price; that is to say, if a line block costs 3d. per square +inch the cost of half tone, three colour half tone and +photogravure would be 7¼d., 3s., and 1s. 2½d. respectively.</p> + +<table summary="costing" align="center" width="auto" border="0" style="margin-top: 2em; margin-bottom: 2em;"> +<tr> + <td> </td> + <td class="center"> A</td> + <td class="center"> B</td> + <td class="center"> C</td> +</tr> +<tr> + <td>Line</td> + <td class="right1">1 </td> + <td class="right1">1 </td> + <td class="right1">1 </td> +</tr> +<tr> + <td>Half tone and swelled gelatine</td> + <td class="right1">2½</td> + <td class="right1">2¼</td> + <td class="right1">2 </td> +</tr> +<tr> + <td>Half tone three colour (three plates<br /> + required)</td> + <td class="right1">9 </td> + <td class="right1">12 </td> + <td class="right1">10½</td> +</tr> +<tr> + <td>Photogravure</td> + <td class="right1">4½</td> + <td class="right1">4¾</td> + <td class="right1">5 </td> +</tr> +</table> + +<p>It must not be thought that if the area of a block is 3 square +inches, the cost will, therefore, be 9d. There is, for obvious +reasons, a minimum size at which the block or plate is +charged although it may be smaller. These minima vary; +in general terms they may be taken as 12 inches for line, +half tone and swelled gelatine blocks, and 20 inches for +<span class="pagenum"><a name="page91" id="page91"></a>page 91</span> +half tone three colour blocks and photogravure plates. +The measurements are the areas of the etched surface, +the actual plate or block may be larger, but for this margin +no charge is made.</p> + +<p>With regard to cost of printing, nothing need be said +about blocks which are set up with the type, namely line, +swelled gelatine and coarse half tone blocks. The price +of printing fine half tones and three colour blocks depends +upon the quality of the paper used and the fineness of the +work. Photogravure plates must be hand printed (photogravure +printing on rotary machines is not considered +here), and skill is required; for ordinary printing on good +plate paper the price would be 10s. to 12s. 6d. per hundred +copies, whilst for India printing the cost would be about +25s. for the same number.</p> + +<h2 style="margin-top: 3em;">LITERATURE</h2> + +<div class="poem"> <div class="stanza"> +<p>Barnes: <i>Illustrating Botanical Papers</i>, Botanical Gazette, +Vol. 43, 1907.</p> + </div><div class="stanza"> +<p>Bock: <i>Zincography</i>, London, 1910.</p> + </div><div class="stanza"> +<p>Cumming: <i>Handbook of Lithography</i>, London, 1904.</p> + </div><div class="stanza"> +<p>Cundall: <i>A Brief History of Wood-Engraving from its Invention</i>, London, 1895.</p> + </div><div class="stanza"> +<p>Gamble: <i>Line Photo-engraving</i>, London, n.d.</p> + </div><div class="stanza"> +<p>Hamerton: <i>Drawing and Engraving</i>, London, 1892.</p> +<p class="i10"><i>Etching and Etchers</i>, London, 1880.</p> +<p class="i10"><i>The Graphic Arts</i>, London, 1882.</p> + </div><div class="stanza"> +<p>Pennell: <i>Lithography and Lithographers</i>, London.</p> + </div><div class="stanza"> +<p>Richmond: <i>Grammar of Lithography</i>, London, 1909.</p> + </div><div class="stanza"> +<p>Robertson: <i>The Art of Etching</i>, London, 1885.</p> + </div><div class="stanza"> +<p>Verfasser: <i>The Half-tone Process</i>, London, n.d.</p> + </div><div class="stanza"> +<p>Wilkinson: <i>Photo-mechanical Processes</i>, London, n.d.</p> + </div> </div> + + <hr /> + +<table class="tn" summary="tn" align="center" style="margin-top: 3em;"> +<tr> + <td class="note"> + + <h4>Transcriber's Note:</h4> + +<p>Some extraneous (duplicated) Headings on otherwise blank pages have been removed.</p> + +<p>Each Footnote has been indented and placed beneath the paragraph to +which it refers.</p> + +<p>The Plates, which were on un-numbered pages, and some of the Figures, +have been moved to (usually) below the paragraphs which first refer to them.</p> + +<p>page 35: 'revelant' corrected to 'relevant' + ... "See also the relevant works cited under Literature"</p> + +<p>page 90: The Table of Costings does not appear to make sense, but has been left as in the original.</p> + +<p>Hyphenation is not consistent in this book.</p> + </td> +</tr> +</table> + + + + + + + + +<pre> + + + + + +End of the Project Gutenberg EBook of The Essentials of Illustration, by +T. G. 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