,,the ,,essentials ,,of ,,illustration ,a ,,practical ,,guide ,,to ,,the ,,reproduction ,,of ,,drawings ,,photographs ,,for ,,the ,,use ,,of ,,scientists ,,others ,by ,t4 ,g4 ,,hill ,reader in ,vegetable ,physiology in the ,university of ,london1 ,university ,college ,,london ,,william ,,wesley ,,son #bh ,essex ,street1 ,strand #aiae ,,printed ,,by ,,the ,,westminster ,,press1 ,,london1 ,w4 ,,contents ,,page ,,intaglio ,,printing #a ,intaglio plates #b ,line engraving #b ,etching #e ,soft-ground etching #f ,mezzotint #g ,photogravure #h ,,plane ,,surface ,,printing #ae ,lithography #ae ,chromolithography #bj ,photolithographic processes #bc ,collotype #bc ,the preparation of illustrated pages #bf ,,relief ,,printing #cc ,woodcuts and engravings #cc ,the ,half-tone process #cg ,the ,half-tone three-colour process #df ,photomechanical line blocks #di ,the drawing of microscopic details #fg ,the drawing of diagrams and apparatus #gb ,the drawing of maps #gf ,the drawing of graphs or curves #gi ,the swelled gelatine process #hd ,the ,relative ,cost of blocks and plates by various processes #hi ,,literature #ie ,,illustrations #a4 ,,plates ,,plate #a ,an original lithograph by ,mr4 ,harry ,becker4 #b ,chromolithograph4 ,messrs4 ,gerrards1 ,ltd4 #c-e ,collotype4 ,messrs4 ,andre1 ,sleigh ,anglo1 ,ltd4 #f ,half tone4 ,swan ,electric ,engraving ,co41 ,ltd4 #g ,half tone4 #h ,photogravure4 #i ,collotype4 ,messrs4 ,andre1 ,sleigh ,anglo1 ,ltd4 #aj ,half tone4 #aa ,half tone4 #ab ,half tone three colour4 _/ #b4 ,,text ,,figures ,tailpiece1 p4 #aa4 ,electrotype from the original wood engraving by ,bewick4 ,tailpiece1 p4 #cj4 ,line block4 ,messrs4 ,bourne ,co4 ,fig4 #a4 ,wood engraving4 ,messrs4 ,edmund ,evans1 ,ltd4 ,fig4 #b4 ,wood cut4 ,mr4 ,g4 ,n4 ,oliver4 ,figs4 #c-f4 ,line blocks4 ,messrs4 ,andre1 ,sleigh ,anglo1 ,ltd4 ,figs4 #g and #h4 ,line blocks1 reproductions of a wood engraving4 ,mr4 ,c4 ,butterworth4 ,fig4 #i4 ,line block4 ,figs4 #aj-ac4 ,line blocks1 reproductions of wood engravings4 ,fig4 #ad4 ,line block4 ,fig4 #ae4 ,line block4 ,messrs4 ,andre1 ,sleigh ,anglo1 ,ltd4 ,fig4 #af4 ,line block4 ,swan ,electric ,engraving ,co41 ,ltd4 ,fig4 #ag4 ,line block4 ,messrs4 ,andre1 ,sleigh ,anglo1 ,ltd4 ,figs4 #ah-bj4 ,line blocks4 ,figs4 #ba-bc4 ,line blocks4 ,messrs4 ,bourne ,co4 ,figs4 #bd and #be4 ,line blocks4 ,fig4 #bf4 ,line block4 ,messrs4 ,bourne ,co4 ,fig4 #bg4 ,line block4 ,figs4 #bh and #bi4 ,line blocks4 ,messrs4 ,andre1 ,sleigh ,anglo1 ,ltd4 ,fig4 #cj4 ,line block4 ,mr4 ,c4 ,butterworth4 ,fig4 #ca4 ,line block4 ,messrs4 ,andre1 ,sleigh ,anglo1 ,ltd4 ,fig4 #cb4 ,line block4 ,mr4 ,c4 ,butterworth4 ,figs4 #cc and #cd4 ,line blocks4 ,figs4 #ce and #cf4 ,line blocks4 ,messrs4 ,andre1 ,sleigh ,anglo1 ,ltd4 ,fig4 #cg4 ,line block4 ,messrs4 ,bourne ,co4 ,fig4 #ch4 ,lithograph reproduced by the ,swelled ,gelatine ,process4 ,artists ,illustrators1 ,ltd4 ,tailpiece1 p4 #hf4 ,line block4 ,messrs4 ,andre1 ,sleigh ,anglo1 ,ltd4 ,,preface ,modern scientific publications1 although they may in some or even many cases equal in their scientific quality the memoirs of earlier workers1 do not1 on the average1 reach a high standard as regards illustration4 ,for instance1 in ,great ,britain botany is pre-eminent in its morphological aspects2 it should therefore follow that the illustrations1 which form so important a part of such papers1 should be beyond reproach4 ,this is not always so1 a fact which must be patent to anyone with the slightest critical knowledge who looks through a typical journal4 ,this is a fact much to be regretted1 since many of the earlier scientists were accomplished draughtsmen and1 indeed1 often artists2 in this connection the ,hookers and ,professor ,daniel ,oliver may be mentioned4 ,the implication is not intended that there are no good amateur draughtsmen nowadays2 there are1 and in some cases possessed of great ability4 ,the beautiful work of ,church in his ,floral ,mechanisms may be cited as an example4 ,it may1 of course1 be argued that any picture which serves to illustrate the particular feature is good enough2 this is the contention of one who takes an insufficient pride in his work4 ,a feature worthy of an illustration deserves the best the author can produce1 more especially as a literary form is still1 fortunately1 preserved or1 at any rate1 aimed at4 ,the reason for indifferent illustrations is primarily due to bad or mediocre drawings1 or to their unsuitability for the kind of reproduction in view4 ,with regard to the first point3 this lack of draughtsmanship often obtains2 when education entirely replaces mere instruction1 it is to be hoped that all students of science will be trained in the rudiments of drawing4 ,meanwhile the difficulty can be partly overcome1 as will be seen later on1 by the simple means of drawing on an enlarged scale1 in order that in reproduction reduction can be made4 ,the second reason1 the onus of which also falls on the authors1 is a lack of knowledge regarding the kind of drawing suitable for the different modes of reproduction2 this is a very important point1 for technical conditions govern even genius itself4 ,authors1 however1 are not always to blame2 it would appear that even editors sometimes are wanting in the requisite knowledge1 for we have known straightforward line drawings reproduced by half-tone2 in other cases the paper used is unsuitable for the reproduction and1 at other times1 the printers are at fault4 ,with a view to remedying1 at any rate in part1 these deficiencies1 a course of lectures1 arranged by the ,board of ,studies in ,botany of the ,university of ,london1 was delivered in the ,lent term of #aiac in the ,department of ,botany of ,university ,college1 ,london4 ,in gratifying the wish expressed by some that these lectures should be given a more permanent dress1 the author feels that some apology is necessary1 for he can lay no claim to authoritative knowledge of much of the subject-matter2 questions relating to the graphic arts and to illustrations1 however1 have always been of interest to him1 so that he has tried various experiments1 often with disastrous results1 and thus has gained some experience4 ,in these matters the author has benefited much through his association with ,professor ,f4 ,w4 ,oliver1 who1 characteristically1 has been ever ready to discuss these problems with1 and to place his knowledge and experience at the disposal of the author4 ,the outline of the ways and means of illustration contained in the following pages is primarily intended for ordinary working scientists1 not for artists1 professional draughtsmen or skilled amateurs4 ,the point of view is mainly botanical1 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 science2 the requirements of other sciences1 however1 have not been overlooked4 ,with regard to other branches of knowledge1 the principles considered will1 it is hoped1 prove of some value to the workers therein4 ,the details of technique have been kept as brief as possible2 in fact1 sufficient only has been said to indicate the main principles involved4 ,in the literature cited1 to which the author is indebted particularly for matters relating to technique1 will be found full1 and sometimes exhaustive1 accounts4 ,with regard to the illustrations1 these have been selected to illustrate the various methods of reproduction described or to demonstrate the points raised4 ,in those instances where the source has not been acknowledged or the draughtsman or photographer mentioned by name1 the figure is by the author3 and since the actual making of plates and blocks is of considerable importance1 the firms1 when known1 responsible for their making are mentioned in the ,table of ,illustrations4 ,in this connexion the author desires to express his appreciation of the skill shewn and care taken by ,messrs4 ,andre1 ,sleigh and ,anglo1 ,limited1 who prepared the majority of the new illustrations which appear in the following pages4 ,the author is indebted to many who have helped in various ways in the production of his work2 particularly is he desirous of expressing his warmest thanks to ,miss ,o4 ,johnston for the charming drawing of ,geranium columbinum 7,plate #b7 and to ,mr4 ,harry ,becker for his beautiful lithograph 7,plate #a74 ,to ,miss ,s4 ,m4 ,baker1 ,dr4 ,w4 ,g4 ,ridewood1 and ,miss ,winifred ,smith thanks are due for the loan of original drawings2 also to ,mr4 ,edward ,hunter and ,mr4 ,hugh ,hunter for information regarding matters of technique and cost4 ,the number of illustrations would have been less but for the generosity of ,messrs4 ,chapman and ,hall1 the ,editors of the ,annals of ,botany1 ,the ,imprint1 and the ,new ,phytologist1 ,professor ,f4 ,w4 ,oliver and ,mr4 ,g4 ,n4 ,oliver in lending blocks4 ,recognition also must be made of the kindness of ,mr4 ,richard ,g4 ,hatton in consenting to the use of certain blocks from his admirable ,craftsman's ,handbook1 of the ,delegates of the ,clarendon ,press for permission to reproduce figure #ad1 and of ,messrs4 ,frederick ,warne and ,co4 for permission to make use of the wood engraving by ,messrs4 ,edmund ,evans1 ,ltd41 of ,kate ,greenaway's charming ,milkmaid4 ,finally1 the author desires to express his sincerest thanks to ,mr4 ,gerard ,t4 ,meynell1 of ,the ,westminster ,press1 for the keen interest he has taken in the work1 for his help with the illustrations1 and for the great care he has taken in the production of the book4 ,university ,college1 ,london ,january1 #aiae4 ,,intaglio ,,printing ,in the biological sciences the massing of illustrations into plates is still the favourite method of illustration1 although text-figures have recently become more numerous4 ,this is partly due to innate conservatism1 for most of the earlier memoirs were so illustrated1 doubtless because it saved time1 since if wood engravings were used with a view to text-figures1 the compositor had to wait for the blocks1 whereas in the case of plates the compositor and the engraver worked independently4 ,also the possibilities of plates are enormous2 they may be very beautiful indeed besides being biologically satisfactory1 for much finer results can be obtained by engraving metal than by engraving wood4 ,then again there are many different processes available for the making of plates1 so that if one proves unsuitable for a subject an excellent reproduction may be obtained by another4 ,before passing on it is desirable to point out the essential differences in the three ways of printing4 ,intaglio printing4 ,if the finger-tips be examined1 many ridges and furrows will be seen on their under surfaces2 if now a thick ink be well rubbed into these so as to fill well the furrows1 and the superfluous ink be wiped off from the general surface1 an impression will be obtained of the furrows on pressing the fingers on to a piece of smooth white paper4 ,better still1 if the copper plate of a visiting card be examined1 the name will be found cut into the surface4 ,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 plate1 an impression can be obtained by placing a piece of damp paper on the plate and passing both through the domestic mangle--the kind with rubber-covered rollers4 ,in each case the principle is the same1 the pressure forces the paper into the depressions of the plate so that it takes up the ink4 ,plane surface printing4 ,this is characteristic of lithography and allied processes4 ,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 drawing4 ,the transfers of childhood provide a further simple illustration1 so also does the hectograph 7jellygraph74 ,relief printing4 ,in this case1 the design is raised above the general surface of the substance4 ,a rubber stamp is an obvious example4 ,it will be noticed that intaglio and relief are the reverse one of the other1 whilst plane-surface printing is intermediate between these extremes4 ,in intaglio1 the ink is taken from a depression2 in relief from an elevation2 and in flat printing from a plane surface4 ,,intaglio ,,plates4 ,there are several methods of making intaglio plates1 but only a few are used in the illustration of scientific papers2 attention however may be drawn to the others1 not only for their own sake1 but also on account of their influence on some modern photo-mechanical processes4 ,,line-,,engraving4 ,line engraving1 by which is meant cutting lines into copper1 steel1 or other suitable material with a burin or graver1 is a very ancient art4 ,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 7niello7 which was made by heating together a mixture of these metals with sulphur4 ,this enamel when once in was very hard to remove1 so that in order to see how their lines were progressing1 the artists rubbed well into the metal1 in order to fill up the lines1 a sticky ink4 ,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 depressions1 which alone contained the pigment1 and take up the ink4 ,a print was thus obtained of the work and so its state was ascertained4 ,metal engraving is carried out in the same fashion at the present time4 ,a flat plate of copper or steel is well polished and is worked upon with a graver or burin1 so that the picture is represented by lines cut into the metal4 ,any line1 however fine1 will give an impression on printing1 hence it is hardly surprising that engraving has long been a popular means of expression by artists1 since force1 depth and delicacy are possible of attainment4 ,the printing is carried out in exactly the same way as by the early metal workers3 the plate is covered with a thick ink which is forced well into the lines and then the superfluous ink is removed4 ,the plate is now ready for printing2 to do this1 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 blanket4 ,the whole is then passed under the roller which forces the paper into the incised lines1 so that not only is the ink picked out1 but a mould of them is taken on the paper1 hence the very finest lines will give an impression4 ,having passed through the press the paper is carefully peeled off1 and thus the print is obtained4 ,with regard to the metal employed1 copper is commonly used1 since it is soft and easy to work2 its softness however is1 in a sense1 a disadvantage1 since the plate will soon wear1 the finest lines being the first to go1 so that a limited edition of good impressions only is possible4 ,to overcome this difficulty1 the plate may be faced with steel1 by which means it is rendered very durable4 ,steel1 although once popular1 is not much used nowadays owing to its hardness and the rapidity with which it rusts4 ,as compared with copper engravings1 steel gives a somewhat harder line1 whilst copper gives a soft line1 but this1 of course1 does not mean that steel engravings are harsh2 the finest work can be done on steel and of remarkable delicacy4 ,at the present day line engraving is seldom or never used as a means of illustrating scientific work4 ,it is obvious that the average scientist has not the time and he certainly does not possess the skill to make his own plates2 the engraver must translate the originals into lines1 so that much consultation would be necessary4 ,further1 a line engraving takes a long time to make1 and most publishers would certainly look at the expense4 ,in the past1 however1 the line engraving was much used1 and very beautiful work was often accomplished4 ,the following works contain outstanding examples4 ,bojanus3 ,anatome ,testudinis ,europaeae1 ,vilnae1 #ahai-ahba4 ,the plates are beautiful engravings by ,lehmann after the drawings by the author4 ,chatin3 ,anatomie ,comparee des ,vegetaux4 ,good steel engravings illustrating the structure of various plants4 ,curtis3 ,flora ,londinensis1 ,london1 #aggg4 ,the illustrations are hand-coloured copper engravings by ,sowerby and others1 many of which1 particularly the earlier ones1 are of outstanding excellence4 ,the engraving is often nothing more than the mere outline of the plant1 whilst in cases where the structures are more massive1 a certain amount of shading is used4 ,the colouring is very good indeed1 and it is obvious that much care was taken not only in the actual painting but also in the choice of pigments which1 as far as can be judged1 are as fresh now as when first used4 ,curtis's ,botanical ,magazine and ,edwards's ,botanical ,register contain some excellent examples of hand-coloured copper engravings4 ,levaillant3 ,histoire ,naturelle des ,oiseaux d',afrique4 ,paris1 #ahje-h4 ,this work contains beautifully coloured engravings by ,feesard4 ,the original drawings were by ,reinold4 ,lyonet3 ,traite ,anatomique de la ,chenille4 ,la ,haye1 #agfb4 ,the plates are amongst the best illustrative of zoological science4 ,martius3 ,flora ,brasiliensis4 ,the earlier volumes1 e4g41 ,vol4 #ac1 ,part ,i1 contain excellent engravings4 ,passaeus3 ,hortus ,floridus4 ,arnheim1 #afad-ag4 ,sowerby and ,smith3 ,english ,botany4 ,london1 #agij-ahff4 ,the illustrations are hand-coloured copper engravings4 ,thuret et ,bornet3 ,etudes ,phycologiques4 ,paris1 #ahgh4 ,this work contains the finest plates ever published in a botanical work4 ,riocreux drew from the preparations1 and his drawings were engraved on steel by ,picart1 ,thomas and others4 ,,etching4 ,etching is a term very loosely used2 strictly speaking it consists in corroding a metal plate or a flat stone with acid1 or other substance possessed of a kindred action1 so that depressions are formed4 ,a pen and ink drawing1 although usually so termed1 is not an etching4 ,briefly the method is this3 a well polished copper1 steel or zinc plate is covered with a substance1 known as the etching ground1 consisting commonly of a mixture of asphaltum1 white wax and pitch1 which resists the action of the acid4 ,the ground may be laid in more than one way2 the simplest1 perhaps1 is to dissolve the etching ground in some solvent such as chloroform1 which readily volatilises1 and to pour the solution on to the plate1 which is tilted this way and that until the liquid is evenly distributed2 the excess is poured off and what remains is allowed to dry1 the plate being kept level during the process4 ,the plate is then warmed until the ground is softened1 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 ground4 ,when the plate is cold1 the drawing may be made by cutting through the etching ground1 so as to expose the underlying copper1 with needles of various sizes4 ,the work is then etched by means of dilute nitric acid4 ,when this is satisfactorily accomplished1 the ground is cleaned off1 the plate well inked with copperplate ink1 and the surface ink removed by coarse muslin4 ,the plate is then gone over with fine muslin1 but the ink must not be removed from the depressions2 finally the damped paper is placed in position and impressions obtained by the use of the copper-plate press4 ,etching1 although suitable1 especially when natural-printed1,a for the illustration of many scientific subjects1 is but seldom employed at the present time for this purpose2 the preliminary announcement of ,warburg's ,die ,pflanzenwelt1 however1 states that some of the illustrations are etchings4 ,footnote ,a3 ,a plate is said to be natural-printed when all the ink is removed except from the depressions2 in artificial printing some ink is allowed to remain on the flat parts4 ,artists frequently1 after removing the superfluous ink1 lightly dab the plate in order to make the pigment spread slightly beyond the actual limits of the depressions2 this is known as retroussage4 ,,soft-,,ground ,,etching4 ,this is a somewhat rare method of reproduction nowadays2 it may1 however1 be described briefly1 for it would appear to be suitable for scientific purposes1 since it should not prove a matter of great difficulty for an author who is a sufficiently skilled draughtsman to make his own plates4 ,the polished copper plate is laid with ordinary ground to which is added lard in a quantity according to the warmth of the weather4 ,over the plate is then placed a sheet1 larger than the plate by an inch or two1 of damp1 thin1 grained paper1 the edges of which are folded over and pasted to the back of the plate4 ,when the paper is dry it will be well stretched and in close contact with the plate4 ,with the hand resting on a bridge1 in order to avoid inadvertent touching of the plate1 the drawing is made on the paper with a pencil of a hardness suited to the softness or otherwise of the etching ground4 ,when the drawing is finished the paper is carefully removed2 wherever the pencil has been used1 the etching ground will adhere to the paper1 so that in such places the metal will be exposed4 ,the plate is then etched and printed as in the normal process4 ,no reproductions of drawings of scientific subjects apparently have been reproduced by this method4 ,examples can conveniently be examined in ,the ,seven ,lamps of ,architecture by ,ruskin4 ,,mezzotint4 ,the characteristic feature of mezzotint is that the subject is translated into tones rather than lines as in the preceding intaglio methods4 ,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 tool1 known as a rocker1 the edge of which is finely toothed4 ,an impression taken of the plate in this condition will give a deep rich tone4 ,the high lights are obtained by scraping and burnishing away the elevations so that there are no pits left to hold the ink1 and1 similarly1 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 depth4 ,impressions are taken in the same way as in the case of etchings4 ,mezzotint apparently has never been used for the reproduction of scientific subjects4 ,indeed1 in a sense1 this process is much too artistic for the purpose4 ,at their best1 illustrations reproduced by this method have mystery and depth and give the imagination much employ2 in a word1 they are subjective rather than objective1 qualities unsuited for our purpose4 ,,photogravure4 ,photogravure may next be considered1 for although it is a photo-mechanical process1 it corresponds to mezzotint4 ,excellent results may be obtained by its use provided the drawings--usually executed in monochrome such as sepia--be really good1 otherwise they are hardly worth reproducing by this relatively expensive method4,a ,footnote ,a3 ,this account refers only to plates made and printed entirely by hand1 not to photogravure for printing on a rotary machine4 ,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 stipple4 ,the photographic part of the process is essentially the same as making a carbon print from a photographic negative4 ,this consists in exposing under the negative the carbon tissue1 which is a mixture of gelatine1 in which is dissolved bichromate of potash1 and a suitable pigment4 ,such a film of bichromate gelatine is1 when dry1 sensitive to light4 ,if no light gains access to it1 the gelatine is readily soluble in warm water2 if light acts upon it1 the gelatine becomes insoluble in proportion to the degree of its exposure4 ,obviously1 the pigment will be retained in varying degrees according to the relative insolubility of the different parts of the gelatine4 ,the carbon tissue having been exposed1 is rolled down on a wet sheet of paper covered with some adhesive and is dried under pressure4 ,the paper is then soaked in warm water when the basis of the carbon tissue easily peels off2 the picture is developed by laving in warm water1 which will dissolve the gelatine in proportion to its exposure to the light4 ,the print when dry is remarkably permanent and1 from the picturesque point of view1 is infinitely superior to the ordinary silver print4 ,the method of making the photogravure plate is1 in outline1 as follows3 ,the original drawing is photographed1 and it is very important that the negative should be as perfect as possible4 ,from the negative1 a positive is made upon transparency carbon tissue which is mounted upon a sheet of plate glass4 ,the procedure is1 in essentials1 exactly the same as described above for the making of a carbon print4 ,this positive when dry may be touched up2 after which a negative1 which also may be touched up1 is made from it upon an ordinary sheet of carbon tissue4 ,the negative so obtained is transferred to a prepared plate of copper1 developed with warm water and dried4 ,the copper plate is prepared as follows3 after being well polished until quite free from all scratches1 the surface is dusted over with finely powdered resin or1 more usually1 bitumen4 ,the plate is then heated until the dust adheres4 ,after the carbon negative has been stuck on to the plate1 developed and dried1 the margins and back of the copper are protected with an acid-resisting varnish4 ,when dry1 the plate is placed in the etching bath of nitric acid or1 more generally1 of ferric chloride4 ,the etching fluid will pass through the thinnest parts of the negative first1 so that the surface of the copper will be etched to a degree corresponding to the thickness of the gelatine4 ,the high lights on the negative obviously will be represented by thick coatings of gelatine1 consequently such parts will be but slightly etched and vice versa4 ,if the plate had not been laid with resin1 the surface after etching would show more or less extensive depressions and elevations2 but the grains of resin protect the copper immediately beneath them from the action of the acid1 which consequently can only dissolve the exposed parts of the metal between the resinous particles4 ,the result is1 therefore1 that the plate is covered over with numberless fine pits of varying depths4 ,the deepest ones will1 on printing1 give the darkest tones1 since they will hold more ink1 the shallower ones will give the lighter tones1 whilst the shallowest and those parts unetched will give the high lights4 ,the plate is usually etched three or four times successively in varying strengths of fluid1 after which the etching ground and gelatine is cleaned off4 ,a strong copper-plate ink is then well rubbed in by means of a dabber1 after which the ink from the surface is removed1 first with a coarse piece of muslin and finally1 with fine muslin4 ,the ink must not be removed from the pits4 ,the first pull is then taken as in a line engraving with a copper-plate press1 and its appearance shows what corrections are necessary4 ,the plate nearly always requires a certain amount of engraving2 the high lights may be improved by means of a burnisher1 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 on4 ,finally1 if a large edition is required1 the plate is steel faced4 ,although much used for the reproduction of pictures1 photogravure is too rarely employed for scientific purposes2 this is to be regretted1 for the process is admirably suited to the reproduction of photographs and drawings with delicate tones4 ,as compared with the usual half-tone1 the cost is high1 and this no doubt militates against its use4 ,examples of outstanding excellence will be found in the ,new ,phytologist1 ,vol4 xi1 #aiab1 plates #e and #f4 ,these are absolute facsimiles of the original drawings by ,mr4 ,mc,lean1 both as regards colour and reproduction of tones4 ,plate #h may also be examined and compared with plates #i and #aj which are reproductions of the same subject in collotype and half-tone respectively4 ,,plane ,,surface ,,printing ,illustration3 ,,plate #a4--;,an original lithograph by ,mr4 ,harry ,becker4 ,,plane ,,surface ,,printing ,,lithography4 ,of these methods of printing1 lithography is the outstanding example3 it is a method of reproduction possessed of great possibilities1 for by its employment a facsimile of any drawing can be obtained4 ,as a means of artistic expression it ranks high amongst the graphic arts1 and1 for the reproduction of drawings of a scientific nature1 it is very popular1 since it meets most requirements and is comparatively inexpensive4 ,the art1 which was discovered by ,senefelder towards the end of the eighteenth century1 depends on the fact that grease and water are immiscible3 a drawing made with a greasy pigment upon a suitable surface adheres very strongly1 whilst those parts free from it retain water1 so that when damped and rolled up 7i4e41 inked71 the ink used will stick only to the lines1 etc41 of the drawing1 but not to the other parts4 ,clearly the surface is all important1 and this is provided by lithographic stone1 a limestone occurring in ,germany1 ,france1 ,england and ,canada4 ,the best stones occur at ,solenhofen near ,munich1 those from other localities being inferior in quality4 ,incidentally it may be mentioned that zinc and aluminium plates are not infrequently used in place of stone4 ,lithographic stones vary in hardness1 colour and grain4 ,for the best work the stone should be homogeneous and of a hardness suitable for the subject2 the colour affords an indication of the hardness1 the lighter-coloured stones1 which are much the commoner1 being softer than the darker4 ,there are two modes of procedure2 the drawing may be made direct on the stone with lithographic ink or crayon--both being mixtures of tallow1 wax1 soap and shellac1 with a sufficiency of pigment to render the drawing visible to the artist--or else the drawing may be made upon transfer paper4 ,the former method1 although the more satisfactory and often used by artists1 is seldom pursued in scientific drawings except when professional draughtsmen are employed4 ,in such cases it may be necessary to reverse the drawing1 which is conveniently done by viewing it in a mirror1 and1 of course1 all lettering must be reversed4 ,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 stone2 he1 the lithographer1 may merely trace the salient features and work the drawing up on the stone4 ,the transfer papers are coated with gelatine1 starch or gum1 or mixtures of these substances1 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 paper1 so that a transfer has only to be damped through the back1 pressed on to the stone and peeled off4 ,the work1 together with more or less of the film1 will thus be transferred on to the stone and1 of course1 will be reversed1 since the part uppermost on the stone will be the back of the original drawing4 ,the original drawings may be made upon the transfer paper direct1 and in so doing mistakes in tracing will be obviated4 ,suitable papers are made for various purposes1 e4g41 smooth for ink work and variously granulated for crayon 7see ,plate #a1 which was drawn by ,mr4 ,harry ,becker on transfer paper74 ,another advantage in drawing directly upon the transfer paper is that the draughtsman can make corrections pretty easily for1 if needs be1 a bad piece of work can be entirely cut out and a fresh piece of paper inserted4 ,assuming that the transfer method has been employed1 the stone must be prepared according as the drawing is made with ink or with crayon4 ,the stone is first thoroughly ground1 in order to rid it of all traces of previous work1 and then polished for ink work or grained--i4e4 roughened--for crayon work1 the small points produced taking up the crayon in proportion to the amount present on the transfer and the pressure used4 ,the transfer is then damped with water1 sometimes with a dilute solution of nitric acid1 and placed in position on the stone1 which is then passed two or three times through the lithographic press until dry4 ,then the back of the paper is damped and the sheet peeled off4 ,the stone is next proved1 i4e41 prepared for printing4 ,it is first carefully examined for broken lines and other blemishes1 which are touched up with ink or crayon4 ,the stone is then painted over with a solution of gum in water which is allowed to dry1 it is then washed in water and rolled up with ink4 ,the drawing will now be clearly visible1 for if properly inked the clear parts of the stone will not take the pigment1 so that any parts which require cleaning up may be deleted4 ,this is accomplished by means of a pencil of snake stone1 a piece of pumice stone1 an acid stump--a rod of hard wood1 the sharpened end of which is dipped into nitric acid--or with a scraper4 ,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 sponge2 then the surface is again gummed and the stone allowed to dry4 ,it is sometimes necessary to re-etch the stone2 if so1 the damp stone is rolled up with thin ink and allowed to dry1 it is then dusted over with finely powdered resin1 the superfluous resin is removed by means of a wet sponge1 and the surface is painted over with a solution of gum arabic mixed with dilute nitric acid4 ,if the resin is well incorporated with the ink1 the work will suffer no damage in the process4 ,the acid gum is then dabbed off with a rag1 the stone is cleaned up with turpentine1 rolled up once more1 gummed and finally set aside to dry4 ,all this appears complicated1 but it is very necessary to get a good surface for printing4 ,the action of the gum does not appear to be clearly understood1 the nitric acid obviously will etch the stone1 so that the gum will easily penetrate4 ,it is sometimes supposed that the arabic acid of the gum enters into a chemical composition with the calcium carbonate1 making a film which is the real ink-resisting surface4 ,this film has not a long life1 so that in printing it is necessary to renew it periodically by the application of gum solution4 ,if possible1 the stone should be allowed to rest for a day or two after proving1 in order that the ink may sink well in4 ,before printing1 the gum is washed off and the stone allowed to remain in the press-room until its temperature is the same as its surroundings4 ,the stone is then thoroughly and evenly damped all over1 placed in the press1 and rolled up with lithographic ink2 the paper is then laid on1 and the whole passed through the lithographic press4 ,after the first few pulls it will be seen whether all is well4 ,the essentials of a good impression are these3 the lines must be black and not grey1 provided black ink is used2 the lines must not be wider or blacker 7smutty7 than those on the stone1 nor must they be ragged or broken 7rotten74 ,in printing1 the stone must be damped and inked before each impression is taken1 and occasionally re-gumming is required4 ,good printing requires a considerable amount of ability1 especially in the case of crayon drawings4 ,the paper used is a very important matter1 the selection of which can be safely left to the lithographer1 provided he be a good one1 unless the author possesses the necessary technical knowledge4 ,if a smooth paper is required1 and the paper is not to be damped before printing1 ,india paper is best and plate paper next best4 ,all coarse or grained papers must be damped before printing4 ,as has already been remarked1 lithography is a good process for scientific work2 but1 unfortunately1 considering the number of lithographic plates published1 really first-class examples are rare4 ,this is largely due to the original draughtsman2 it is unreasonable to expect a lithographer1 in all probability ignorant of the subject of the plate1 to turn out first-class reproductions of drawings which are obviously bad4 ,on the other hand1 lithographers vary greatly in their capabilities1 and indifferent plates may be entirely due to their ability not being first rate4 ,as drawings have to be traced1 mistakes are apt to occur2 the proofs should1 therefore1 be carefully examined1 for a certain amount of correction can be made on the stone4 ,the following works contain excellent lithographs1 which should be studied by those interested in the subject4 ,bornet et ,thuret3 ,notes ,algologiques4 ,paris1 #ahgf-ahhj4 ,this contains some of the best work1 illustrative of science1 known to the present author4 ,the original drawings mostly were made by ,bornet1 and the lithography was carried out by ,riocreux--one of the best if not the greatest of botanical artists--,arnoul1 ,picart and ,pierre4 ,davis and ,thurnam3 ,crania ,britannica4 ,london1 #ahfe4 ,mirbel3 ,sur le ,cambium1 ,paris1 #ahdb4 ,the plates provide excellent examples of ink lithography by ,laplante4 ,von ,mohl3 ,schriften botanischen ,inhalts4 ,tuebingen1 #ahde4 ,good examples by ,federer4 ,the first volumes of the ,annales des ,sciences ,naturelles 7,paris7 may be referred to for lithographic work earlier than the above 7#ahbj74 ,for more modern examples the following may be consulted3 ,blackman and ,welsford3 ,fertilisation in ,lilium1 ,annals of ,botany1 ,vol4 #bg1 #aiac4 ,gravis3 ,recherches anatomiques sur les organes vegetatifs de l',urtica ,dioica1 ,bruxelles1 #ahhe4 ,this memoir contains both good and indifferent plates4 ,keibel3 ,normentafeln zu ,entwicklungsgeschichte der ,wirbeltiere1 ,jena1 #aijd4 ,reed3 ,a ,study of the ,enzyme-secreting ,cells in the ,seedlings of ,zea ,mais and ,phoenix dactylifera4 ,annals of ,botany1 ,vol4 #ah1 #aijd4 ,semon3 ,zoologische ,forschungsreisen in ,australien1 ,jena1 #aijd4 ,vaizey3 ,on the ,morphology of the ,sporophyte of ,splachnum luteum1 ,annals of ,botany1 ,vol4 #e1 #ahij4 ,woodburn3 ,spermatogenesis in ,blasia pusilla1 ,annals of ,botany1 ,vol4 #bg1 #aiac4 ,several memoirs in the ,fauna und ,flora des ,golfes von ,neapel 7,berlin7 are illustrated by excellent lithographic plates4 ,many good examples of chromolithography also will be found there4 ,,chromolithography4 ,lithography is much used for the reproduction of coloured pictures and illustrations1 the process being termed chromolithography4 ,the principles involved are the same as for ordinary work1 but it is necessary to print from several stones1 one for each colour4 ,it is obvious that much skill is required1 for the employment of different colours will give a large number of secondary and tertiary tints when printed one above the other in various combinations4 ,thus1 by printing part of a design in yellow and the other part in blue1 the finished product would show three colours--yellow1 green and blue1 and by the use of three primary colours a large number of different tints may be obtained4 ,as already mentioned1 each colour is printed by a separate stone1 there is thus no limit--excepting that of expense--to the number of different colours which can be obtained4 ,in practice it is usual to make an outline of the essential parts of the composition on a stone1 known as the keystone1 which is not necessarily used in printing the picture4 ,an impression of this outline is taken upon a sheet of paper1 which is used to transfer the design on to the stones1 on each of which the artist will draw only those parts which he desires to be printed in one particular pigment4 ,although the sequence of colours is generally blue1 red and yellow1 it is obvious that various changes in this order must be made according to the colours used and the exact tint required4 ,for instance1 a body colour such as cadmium yellow would precede a glaze such as madder-lake2 again1 two distinct tints may be obtained from red and blue1 for example1 according to the order of printing--red upon blue will give a mauve1 whilst blue upon red will give a purple4 ,a knowledge of pigments is thus all important1 and in printing1 the superposition must be perfect4 ,plate #b is an example of a chromolithograph4 ,miss ,o4 ,johnston first drew the outline of the plant1 which was phototransferred on to the stone4 ,an impression was then pulled and tinted by the artist1 and from this tinted impression the colour stones were made by the lithographer4 ,it may be added that only three colours were used in printing the plate4 ,examples3 ,baur3 ,einfuehrung in die experimentelle ,vererbungslehre 7,plate #a74 ,berlin1 #aiaa4 ,bruce and others3 ,a ,note on the ,occurrence of a ,trypanosome in the ,african ,elephant4 ,proceedings of the ,royal ,society of ,london1 ,b4 ,vol4 #ha1 #aiji4 ,cropper3 ,the ,development of a ,parasite of ,earthworms4 ,id4 ,vol4 #he1 #aiab4 ,oliver3 ,on ,sarcodes sanguinea4 ,annals of ,botany1 ,vol4 #d1 #ahhi-ahia4 ,rubbel3 ,u,eber ,perlen 444 ,zoologische ,jahrbuecher1 ,vol4 #cb1 #aiaa-ab4 ,biometrika1 #aijf-g1 ,vol4 #e1 ,plate #bc4 ,mention has been made of the value of a knowledge of colours4 ,the subject is much too extensive to be considered adequately on the present occasion even if it were desirable2 its importance1 however1 warrants a few passing remarks4,a ,footnote ,a3 ,see ,ridgway3 ,color ,standards and ,color ,nomenclature4 ,no two people will describe in the same way the colour of1 say1 a rose petal2 both will have a different conception of the colour crimson4 ,the majority have but a limited sense of colour1 and even when this faculty is possessed1 the personal equation looms large2 further1 the ordinary names of colours are quite inadequate for descriptive purposes4 ,for these reasons the importance of a scientific system of colour nomenclature and colour standards is all important4 ,by the use of such a scheme1 the exact colour of an object can be found by comparison with an adequate chart1 and the name there given will convey to others exactly what colour is described or desired4 ,the plumage of a bird or the colour of a flower can thus be described correctly1 and an author can indicate exactly the colour desired in certain parts of a chromolithograph or other reproduction in colour4 ,illustration3 ,,plate #b4--;,,geranium ,,columbinum4 ,a chromolithographic reproduction of a drawing by ,miss ,o4 ,johnston ,,photolithographic ,,processes4--,of these methods of reproduction there are several1 their value lying in the fact that the originals can be reduced or enlarged with the greatest of ease4 ,the general principles are as follows4 ,a photographic negative is taken of the original drawing and a positive made on a film of bichromate gelatine4 ,wherever light reaches the film1 the gelatine is rendered more or less insoluble according to the intensity of the light acting upon it2 through the dark parts of the negative but little light will pass1 so that the gelatine will remain soluble4 ,the exposure of the positive having been made1 the film1 which may be mounted on paper1 is inked with lithographic ink in the dark room and then washed4 ,the pigment will adhere to those parts acted on by light1 but will wash away from those regions unacted upon2 obviously the half-tones will retain ink in direct proportion to their density4 ,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 ink1 whilst the high lights will retain water and so will not be inked4 ,the intermediate tones will take the pigment according to their density4 ,in distinction to the previous methods1 corrections cannot be made except in so far as the negative can be touched up4 ,,collotype4--,of the various photolithographic methods which have from time to time been employed1 collotype is the one in most general use at the present time1 especially for the reproduction of photographs4 ,collotype is a simple process which does not require so extensive a technical knowledge and ability as some of those previously described4 ,but notwithstanding this1 the results are sometimes unsatisfactory and unequal2 faults due to indifferent originals and to unsatisfactory conditions obtaining in the work rooms4 ,the great drawbacks to good collotype are cold and dampness1 and it is for these reasons that continental firms1 blessed with a more stable climate1 often produce much the best work4 ,provided the workshops are properly heated1 the collotypers of this country ought to be able to turn out good work at all times of the year2 indeed1 the best firms do4 ,for this and for other processes in which photographs form the originals to be reproduced1 authors should send the negative to the collotyper2 if this be impossible1 positives of the best possible quality1 printed on ordinary ,p4,o4,p4 paper1 toned to various shades of purple1 and also on smooth bromide paper1 in ordinary black tones1 should be provided in order that the collotyper can choose the print he most prefers to work with4 ,also1 it is usual to glaze the prints4 ,the method is as follows4 ,a piece of british plate glass1 about half-an-inch in thickness1 is ground on one side with fine emery powder1 and then thoroughly washed and dried4 ,the plate is covered with a filtered mixture of the colloids sodium silicate and dextrine or albumin1 and placed in a warm oven to dry4 ,if metal plates are used1 such as zinc or copper1 this preliminary coating is unnecessary2 glass plates1 however1 must have the substratum in order that the sensitised gelatine--which is next put on--may stick4 ,when the plate is dry1 it is thoroughly washed with water in order to remove any free silicate2 it is then dried and put away until required for use4 ,the sensitising solution is made up of gelatine and bichromate of potash dissolved in water2 before use it is filtered1 freed from air bubbles and heated to not more than #abj deg4 ,f4 ,the plate is now placed on a stand1 which is provided with levelling screws1 in the oven1 and1 when the temperature has reached #abj deg4 ,f41 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 plate4 ,the oven is kept at a constant temperature1 #abj deg4 ,f41 until the gelatine is dry1 when it is allowed to cool gradually4 ,whilst the gelatine is setting1 precautions against vibration must be taken else the plate will be spoilt4 ,when dry1 the collotype plate is sensitive to light and moisture2 its surface shows a more or less regular series of convolutions which resemble those of the outer surface of the human brain1 although1 of course1 very much smaller4 ,the character of the grain is very important1 for if it be too fine it will not take up a sufficiency of ink1 and1 on the other hand1 if too coarse it will yield coarse impressions4 ,a reversed negative1 of a quality beyond reproach1 must be made of the original2 if the subject is dark or has heavy shadows the negative is frequently slightly over exposed so as to soften them4 ,the collotype plate is then exposed under the negative and washed in cold water until the yellow bichromate no longer comes away4 ,it is then dried4 ,in printing1 the plate is damped and rolled up with ink as in lithographic printing2 the amount of ink adhering to the film depends on the extent to which the different parts have been acted on by the light1 as has already been mentioned4 ,the moistening of the plate--mis-termed etching--is best done with dilute glycerine containing #ge per cent4 of water1 which when first applied should be allowed to remain on for about half-an-hour4 ,the excess of moisture is taken up with a sponge or a ball of rag1 and then the plate is inked and printed in a lithographic or a collotype press4 ,the picture is usually masked with tin foil in order that its edges may be quite clean4 ,of the faults which may occur1 the following may be alluded to4 ,a mottled appearance may obtain in the high lights2 this is due to the coating of gelatine being too thick4 ,more commonly1 the reproductions may appear flat owing to the degradation of the high lights2 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 bichromate1 or that the temperature has been too low4 ,the following contain good examples of collotype4 ,karsten and ,schenck3 ,vegetationsbilder1 ,jena4 ,oliver3 ,notes on ,trigonocarpus and ,polylophospermum4 ,new ,phytologist1 ,vol4 #c1 #aijd4 ,semon3 ,zoologische ,forschungsreisen in ,australien4 ,jena4 #aiab4 ,thompson3 ,the ,anatomy and ,relationships of the ,gnetales4 ,annals of ,botany1 ,vol4 #bf1 #aiab4 ,see also ,plates #c1 #d1 #e and #i in the present work4 ,,the ,,preparation ,,of ,,illustrated ,,pages4 ,of the processes dealt with1 photogravure lithography and collotype are those most generally used at the present day for the printing of plates or insets4 ,half-tone also is employed1 a process which will be considered later since it is essentially relief printing4 ,this1 therefore1 is a convenient opportunity to make a few general observations on plates4 ,plates should only be employed for the reproduction of subjects of such complexity that cannot be reproduced satisfactorily by figures in the text4 ,a plate or page made up of several illustrations should look well as a whole2 in other words1 it should not outrage all the canons of composition1 it should have some pictorial effect4 ,at the same time1 for facility of reference1 the individual figures should run in a convenient sequence4 ,this latter point is so important that a plate composed really well is distinctly rare1 for a compromise nearly always has to be made4 ,at the same time there are1 apparently1 comparatively few authors who pay much attention to plate design4 ,although it is not desired to write of the laws of pictorial composition1 attention may be drawn to a few points which are amongst those generally neglected4 ,the figures should not be crowded together2 a reasonable amount of margin should be left around each4 ,they should be arranged1 as far as possible1 in such a way that a sense of balance is maintained4 ,as to how this is to be accomplished will depend upon the nature of the illustrations2 if they are all about equal in tone1 the largest ones should preponderate towards the base of the plate1 and not vice versa4 ,the difference which this makes will be obvious if the two accompanying illustrations 7,figs4 #a and #b1 ,plate #c7 be compared4 ,the first is a reduced copy of the plate as it was published3 it will be noticed that it has a top-heavy appearance1 which is corrected in the second figure by the simple device of turning it upside down4 ,illustration3 ,,plate #c4 ,if1 on the other hand1 the figures are some lighter and others darker1 the latter should form the base1 since low tones give the idea of solidity2 this is so marked that in cases where the figures vary much in size and tone1 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 ones4,a ,footnote ,a3 ,if1 of course1 the reader understands chiaroscuro1 he will take no notice of this paragraph1 but arrange his plates in accordance with his ability4 ,an examination of the figures on ,plates #d and #e will roughly illustrate these points4 ,the upper figure of ,plate #d is well designed1 and no improvement could be made1 bearing in mind the compromise alluded to above4 ,the lower figure is1 however1 not so good1 it was obviously a difficult one to arrange2 it would have been improved if ,figs4 #bc1 #bf and #bh could have been placed in the top tier1 but this would have seriously disturbed the sequence4 ,the first illustration on ,plate #e is well designed2 it would1 however1 have been improved by interchanging #h;,a and #aa;,b4 ,illustration3 ,,plate #d4 ,illustration3 ,,plate #e4 ,we may now pass on to the individual figures2 these should shew the essential features1 together with some surrounding and comparatively extraneous matter2 often there is included too much of unimportance and its retention means a waste of valuable space4 ,the first thing to do1 therefore1 is to trim1 if needs be1 the figures2 their shape is more or less immaterial1 provided that in cases where there are a large number of illustrations on one plate1 they are not all alike4 ,the ,american fashion of circular figures is particularly displeasing1 at any rate to the author4 ,having trimmed the figures1 the next point to decide is whether any require reduction2 if they do1 cut out pieces of paper 7referred to as patterns below7 of the size which the figures will ultimately appear3 on the whole1 it is better to avoid reduction of the originals1 for without a good deal of experience it is very difficult to judge exactly what the result will be2 a good idea1 however1 may be gained by the use of a diminishing glass4 ,the size of the available surface of the plate should now be ruled on a white sheet of fairly thick cardboard1 and the figures1 or their patterns1 arranged so as to be easy of reference1 to compose as well as may be1 and spaced in such a way that1 in the case of a quarto plate to be folded vertically1 no figure is placed so that the fold will pass through its centre4 ,nothing is more irritating than having an illustration spoilt in this way4 ,all this may be done by arranging in different ways until a satisfactory result is obtained1 a process which may take an hour or two4 ,the figures should then be pasted down1 covered with several sheets of blotting paper and placed in a press4 ,a press is seldom available2 when such is the case1 a number of heavy books serve equally well4 ,the lettering must next be attended to4 ,the individual figures are usually designated by numbers2 this is a bad method1 since it involves referring to the description of the plate4 ,the best way is to use a number1 and after it to add the name of the plant or animal1 and1 if needs be1 a description as short as may be4 ,if the author can print or write reasonably well1 well and good2 if not1 it is better to attach a slip to the plate with full directions relating to lettering1 and to write in pencil on the plate the titles1 etc41 required in the proper places for the guidance of the craftsman4 ,the typewriter is sometimes employed for this purpose by authors2 it is purely a matter of taste1 but some readers feel a slight shock when this method is resorted to4 ,in some cases a key to the plate printed on tough translucent tissue paper and having the necessary information1 guide lines1 etc41 is inserted with the plate4,a ,footnote ,a3 ,see ,kerner and ,oliver3 ,natural ,history of ,plants 7,first ,edition7 ,london1 #ahid4 ,in the case of glossy chromolithographs this practice is best avoided1 for the key is apt to stick to the plate if too much pressure is used when the book is bound4 ,with regard to the catch letters used to indicate different parts3 these should be as obvious as possible1 and the guide lines should be either in black or in white ink1 according to the general tone of the illustration4 ,these lines should be conspicuous without being heavy4 ,not infrequently they1 together with the lettering1 are printed on the plate by a second impression in red ink4 ,the foregoing is primarily the business of the author2 with regard to editors and publishers1 all plates should be mounted in a manner to facilitate reference and should be printed on suitable paper2 the former is seldom or never done4 ,all plates which must be constantly referred to in reading the text should have a selvedge as broad as the book1 so that when unfolded the whole plate is visible1 no matter what page is being read4 ,this would1 no doubt1 prove an additional expense1 but this should not militate against the suggestion here made1 not by any means an innovation1 for in many cases it would save the expense of mounting on guards1 and1 further1 the additional expenditure could be saved several times over in other ways4 ,with regard to paper1 this generally is satisfactory2 unfortunately1 highly glazed paper1 mis-termed art paper1 with an enamelled or chromo surface1 and consisting chiefly of china clay and size1 is generally used for printing the best half-tone reproductions4 ,for this purpose a paper with a suitable surface1 obtained by means other than those mentioned and not too costly1 is highly desirable1 since art paper has the reputation of being not at all permanent1 owing to the deleterious action of moisture1 and is somewhat brittle4 ,when used1 art paper1 if folded1 should have a proper paper hinge along the fold4 ,half-tones are occasionally printed on a kind of vegetable parchment1 a paper which should be more extensively used since it will sometimes1 but not always1 give as good a reproduction as art paper1 and the final result is more pleasing from the artistic point of view4 ,illustration3 ,g4 ,oliver1 del4 ,,relief ,,printing ,illustration3 ,little maid1 little maid1 ,whither goest thou8 ,down in the meadow ,to milk my cow4 ,fig4 #a4--;,a wood engraving1 by ,edmund ,evans1 from the original drawing by ,kate ,greenaway4 ,reproduced by permission of the publishers1 ,fredk4 ,warne ,co4 ,,relief ,,printing ,in order that illustrations may be incorporated in the text1 the blocks used must be in relief the same as the type2 a mixture of intaglio and relief is impossible1 for the whole surface must be level in order to be inked by the rollers1 which deposit the pigment evenly1 so that only one tone of colour--that of the ink--is possible4 ,up to quite recent times wood cuts and engravings were the only means available for text-illustrations1 so that this method may next be considered4,a ,footnote ,a3 ,see ,treviranus1 ,c4,l43 ,die ,anwendung des ,holtzschnitts zur bildlichen ,darstellung von ,pflanzen4 ,leipzig1 #ahee4 ,,wood ,,cuts ,,and ,,engravings4 ,the invention of illustrating by means of wood blocks followed closely on the heels of the use of moveable types for printing4 ,the ,chinese were the first1 as far as is known1 to use these methods of printing and illustration2 in the western world the first wood blocks date from the beginning of the fifteenth century4 ,all the earlier cuts were made1 commonly on pear wood1 on the longitudinal face of the wood1 in technical language on the plank1 and seemingly1 in many instances1 were made from drawings in ink4 ,by cutting on the plank1 the craftsmen were enabled to make large blocks1 but were prohibited from doing anything more than relatively simple and straightforward work4 ,such blocks are known as wood cuts2 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 date4 ,this is1 strictly speaking1 wood engraving1 an art which almost entirely1 if not quite1 superseded the older craft1 on account of its great possibilities2 indeed1 wood engravers imitated metal engraving so closely as to deceive many4 ,but such work was enormously laborious2 for instance1 in the case of a fishing net1 if the string were to be printed black1 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 relief4 ,but few artists would do this of their own free will1 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 lines1 shading1 etc41 had to be faithfully copied4 ,this point may be illustrated by the accompanying cut 7,fig4 #b71 which was made by my friend ,mr4 ,geoffrey ,oliver1 who at the time was totally uninstructed in the art and knew nothing of its literature4 ,it will be seen that he1 quite unconsciously1 treated his wood in the same way as an engraver would his metal2 the result1 of course1 is just the opposite to metal engraving since the printing of the wood block is the reverse to intaglio4 ,illustration3 ,fig4 #b4 ,in fact1 the cut illustrates the three fundamentals of wood engraving2 the white line made by cutting out the wood so that no impression will be obtained when printed2 the white space which is similarly obtained2 and the black space1 which is made by leaving the wood untouched4 ,it was1 however1 necessary to employ the black line1 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 sky4 ,in a word1 the little picture illustrates very nicely the legitimate use of wood in the graphic arts4 ,as already remarked1 the majority of the earlier wood cuts and engravings are reproductions of line drawings1 so that although we may admire and often marvel at the technical ability of the engraver1 the credit for what artistic merit such illustrations may possess must1 in the majority of cases1 go to the draughtsman4 ,the work of the earlier wood engravers may be conveniently studied in ,a ,lyttel ,booke of ,nonsense1 by ,r4 ,d41 ,london1 #aiab4 7,see also the relevant works cited under ,literature1 p4 #id74 ,bewick1 of course1 is an outstanding example of an artist who used wood engraving for illustrating natural history2 the methods he pursued may be studied in the tailpiece on p4 #aa1 which was printed from an electrotype of the original block4 ,wood engraving1 up to quite recent times1 was the method of reproducing text figures2 not only for scientific books and periodicals1 but also for general literature and journals4 ,much of this work is of outstanding excellence2 for scientific work the following may be studied3 ,duchartre3 ,elements de ,botanique4 ,paris1 #ahfg4 ,the drawings were made by ,riocreux and engraved by ,leblanc4 ,baillon3 ,histoire des ,plantes1 ,paris1 #ahhg4 ,this work contains some beautiful wood engravings1 reproductions of drawings by ,faguet4 ,bentham3 ,handbook of the ,british ,flora1 ,london1 #ahfe4 ,the engravings are from drawings by ,w4 ,h4 ,fitch4 ,deschanel3 ,natural ,philosophy1 ,london1 #ahij4 ,the engravings1 many of which are of excellent quality1 are by ,laplante1 ,rapine and others4 ,in many cases1 notably in the representation of the rays of light passing through lenses and also in the illustrations of snow crystals1 the use of the white line is admirably demonstrated4 ,kerner3 ,pflanzenleben1 ,leipzig1 #ahhh4 ,this contains some excellent engravings by ,winkler and others4 ,le ,maout et ,decaisne2 ,traite general de ,botanique1 ,paris1 #ahgf4 ,this work contains splendid examples by ,riocreux and ,steinheil 7see ,fig4 #h74 ,oliver3 ,first ,book of ,indian ,botany1 ,london1 #ahfi4 ,this contains some characteristic work of ,w4 ,h4 ,fitch4 ,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 although1 of course1 in the present instance1 the blocks are in relief 7,fig4 #a74 ,from the foregoing account it is obvious that the engraving even of a small illustration1 except it be in mere outline1 involves a considerable amount of labour2 in fact1 if the subject were large it was usual to cut it up into areas and distribute between several engravers1 the finished blocks finally being joined together to make the block of the whole picture4 ,hence it is not surprising to find that when the photo-mechanical processes were perfected1 the older methods of reproduction were ousted by the newer1 more especially since they are much less expensive2 these1 therefore1 may next be considered4 ,,the ,,half ,,tone ,,process4--,for the making of a relief block by photo-mechanical means1 the main difficulty is the proper rendition of the tones intermediate between black and white2 this has been solved1 at any rate in part1 by the discovery of the half-tone process4 ,if an ordinary photographic negative be highly magnified1 it will be seen that the high lights1 the low lights1 and the intermediate tones are made by the varying density of the reduced silver4 ,in the lighter parts the small black particles are surrounded by colourless areas1 whilst in the dark regions small colourless patches are surrounded by black areas owing to the closeness of the particles of silver 7,plate #e1 ,fig4 #b74 ,what is required1 therefore1 is a relief block which will print a number of dots of equal density but of unequal size4 ,vervasser illustrates the point in an ingenious way3 a plate1 covered with a number of cones1 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 them4 ,the section of such a plate would therefore shew a curve 7,fig4 #c72 now if the truncated cones be brought down to one level and a print taken from them1 the high lights would be represented by black dots surrounded by white areas and so on4 ,illustration3 ,fig4 #c ,this illustrates the principle which obtains in the making of half-tones in which the image is made up of a large number of dots varying in size but all equally dense1 so that when viewed from a suitable distance the dots are individually invisible but compose to give gradations of light and shade4 ,in other words1 the structure obtaining in a photographic negative is1 in a sense1 realised by optical chemical means1 although the dots in a half-tone block are much coarser than those in a negative 7,plate #e1 ,fig4 #c74 ,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 7,fig4 #d74 ,as a matter of fact1 each screen consists of two plates of glass similarly ruled and cemented face to face so that the lines intersect4 ,illustration3 ,fig4 #d ,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 reproduction2 this1 however1 is not the case2 if the screen be placed in a proper position relative to the negative and the size of the diaphragm of the camera1 the picture will be reproduced in a series of dots of varying size4 ,the optical and other reasons for this phenomenon must be sought elsewhere1,a but the following brief consideration will serve to illustrate what happens4 ,the rays of light which ultimately reach the sensitive plate are acted upon by two lenses1 that of the camera and the meshes of the screen1 each one of which acts as a lens on the principle of the pin-hole camera4 ,each mesh1 therefore1 brings the image of the diaphragm to a focus on the negative1 but the lens of the camera focusses the picture as a whole1 thus the amount of light falling on the different pin-holes will vary in intensity1 and hence the dots produced will vary in size1 for it is assumed1 with good reason1 that each dot is built up from its centre and radially expands according to the amount of light acting upon it4 ,footnote ,a3 ,see ,verfasser1 loc4 cit41 p4 #id4 ,it is obvious that the quality of the resulting picture will depend1 other things being equal1 upon the coarseness of the screen employed4 ,screens are ruled with lines varying from #ej to #djj to the inch3 the lower rulings give very coarse reproductions1 and are only used for posters1 whilst the higher rulings yield very fine impressions and are employed only for the best work4 ,it is hardly necessary to remark that the finer the screen the better must be the skill of the printer4 ,to illustrate the difference in the results obtained by the use of different screens1 the two figures on ,plate #f have been prepared2 both were made from the same negative1 but for the upper figure a #ajj-line screen was used1 and for the lower a #bjj-line screen4 ,it will be observed that there is more contrast in the former1 and more detail in the latter4 ,authors should therefore mention when sending in their original pictures the qualities they require in the reproduction2 it must1 however1 be remembered that the blocks made from the finer ruled screens will not print satisfactorily except on more or less highly glazed paper1 to the use of the art varieties of which there are objections on aesthetic and other grounds4 ,illustration3 ,,plate #f4 ,half ,tone reproduction of a photograph by ,mr4 ,w4 ,rowan4 ,part of a shingle beach shewing plants of ,sea ,blite 7,suaeda fruticosa7 and a ring plover's nest with four eggs4 ,before passing on it may be mentioned that screens with patterns other than that represented in ,fig4 #d are sometimes employed2 for instance1 the wavy-line screen gives the impression of coarse collotype4 ,the preparation of the blocks may now be briefly dealt with4 ,a negative of the picture1 using a screen suitable for the purpose1 is taken on a special dry gelatine plate 7process plates7 or on some other form of negative1 e4g41 wet collodion which is most commonly employed4 ,this negative requires very careful development in order to get the dots right4 ,from the negative a positive is made upon a copper or zinc plate1 suitably coated with a sensitive film4 ,the usual practice is to coat the polished metal plate with a mixture of water1 albumen1 fish glue1 ammonium bichromate1 chromic acid and ammonia2 the plate is then dried and1 when cooled1 exposed under the negative4 ,the action of the light on such a film1 the essentials of which are the albumen1 the glue or gelatine and a chromate1 has already been described4 ,the mixture becomes more or less insoluble in water1 according to the intensity of the light falling upon it4 ,the positive is now rinsed in water1 and is sometimes stained with an aniline dye in order to render the film more visible4 ,next it is developed in a stream of water until the surface of the metal is visible between the dots1 the last traces of the soluble gelatine being removed with warm water4 ,after drying1 the plate is evenly heated over a ,bunsen burner until the dots of gelatine mixture turn chocolate colour1 when the plate is allowed to cool gradually4 ,this is known as burning in4 ,the plate1 if necessary1 is now touched up and the back1 sides and margins varnished in order to protect them from the acid3 when the varnish is dry1 the plate is etched in a weak solution 7about #b-a_/b per cent47 of nitric acid if the metal be zinc2 if the plate be copper1 it is usually etched with a solution of iron perchloride4 ,on taking a proof1 there is almost certain to be a lack of contrast1 the plate is then fine etched1 by which means a considerable improvement can be made2 and1 by covering certain parts with an acid-resisting substance 7stopping out71 it is possible to fine etch locally4 ,incidentally it may be mentioned that machine etching1 by which a fine spray of the etching fluid is distributed over the plate1 has recently come into vogue1 for it is claimed that the results print better and are in other ways an improvement upon the older method4 ,the plate may now pass through the hands of an engraver1 who removes any blemishes1 as far as is possible1 improves the high lights1 and so on2 in fact1 a skilful engraver can improve the plate considerably4 ,after the plate is trimmed1 and the superfluous metal cut out by means of a routing machine1 it is firmly tacked to a wooden mount1 usually of oak1 but sometimes of mahogany1 especially if the plate is large4 ,in order to obtain the best results1 the printing1 in a typographical machine1 should be done on highly calendered paper--so-called art paper2 in fact1 this is absolutely essential if a fine screen has been used2 it is only the blocks made with the coarser screens that will give fair prints on ordinary paper4 ,for this reason reproductions made by the half-tone process are very generally treated as plates unless the glazed paper is used throughout the book4 ,the process is used principally for the reproduction of photographs1 and for pencil or wash drawings4 ,with regard to photographs1 it has already been mentioned that authors should send the negative or two or three prints differently toned1 in order that the operator can choose the one most likely to give the best result4 ,it is sometimes difficult in a photograph of a landscape to obtain a negative in which the particular feature it is desired to represent--e4g41 in photographs of vegetation--stands out with the requisite contrast4 ,this is due to the position of the sun at the time of exposure1 or to the use of ordinary plates4 ,the remedy for the first is to take the photograph when the proper light obtains2 with regard to the second1 the use of colour correct plates1 together with a colour screen in front of the lens1 will obviate the defect4 ,since for scientific purposes the correct interpretation of the various tones of the vegetation1 for example1 may not be essential1 variously coloured screens may be used in order to emphasise a particular feature4 ,for instance1 it will be noticed how well the bushes in ,plate #g stand out4 ,this effect was obtained by the use of a panchromatic plate in conjunction with a red colour screen4 ,illustration3 ,,plate #g4--;,half ,tone reproduction of a photograph taken by ,dr4 ,mees through a red screen4 ,with regard to drawings in wash1 charcoal or pencil1 in which there are half-tones2 these are better drawn on an enlarged scale1 especially if the author is not a skilled draughtsman1 for improper gradations in shading and other imperfections will not appear so noticeable in the reduced reproduction4 ,originals should all be made in one colour2 in the case of wash drawings1 diluted ,indian ink 7really ,chinese ink7 will give excellent results4 ,in making pencil drawings1 a fairly stout hand-made paper with not too much grain should be used4 ,if the drawing is to be of some size1 the paper may be damped and pasted by its edges on to the drawing board1 it will then be stretched quite flat and will not cockle when dry4 ,the outline of the object may first be sketched in lightly with a soft pencil and then the shading may be proceeded with4 ,to do this1 broad-pointed soft pencils1 #b ,b1 #c ,b1 or #d ,b1 should be used1 and it is better generally to work from the high lights to the shadows4 ,to avoid rubbing finished parts1 the work should proceed from the top of the board downwards1 especially in the case of large drawings4 ,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 softness1 and1 of course1 ,india rubber may be employed where it is desired to reduce the density of the shading4 ,when finished1 the edges of the various parts may appear woolly owing to the rubbing of the lead2 this may be cured by cleaning up the edges with a trimmed piece of ,india rubber1 but in so doing there is always a risk of rubbing out part of the shading1 especially if the outline be at all intricate4 ,if preferred1 all the shaded parts may be fixed by painting them over with a suitable solution1 gelatine for instance1 paying particular attention in following the correct outline4 ,when dry1 the application of soft india-rubber will soon clean up the blurred edges4 ,if charcoal be used the same procedure may be followed4 ,charcoal and pencil drawings should be fixed1 in order to prevent rubbing1 before sending to the block makers4 ,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 atomizer4 ,a very good fixative may be made by dissolving a little gelatine in hot water and applying it whilst hot by means of a broad1 flat camel hair brush1 or ordinary milk may be used in a similar way4 ,after the fixative has been put on1 the drawing should be pinned up by one corner--unless1 of course1 it was pinned up before the fixative was employed1 which is the best way when the fixative is an alcoholic solution--and allowed to dry2 it may then be placed under pressure in order to flatten it1 for fixed drawings generally shew a tendency to curl1 especially when the preparation used for fixing has only been applied to one surface of the paper4 ,in making drawings for reproduction by means of the half-tone process1 there are a few general points to which attention should be paid4 ,it should be remembered that there is not infrequently a tendency towards flatness in the reproduction2 it is therefore important that the originals should be plucky1 and1 on the whole1 it is better to exaggerate with regard to high light and shade1 especially if there is much modelling or perspective4 ,finally1 with regard to lighting1 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 lights1 shades and shadows referable to this main direction of illumination4 ,a high relief will thus be obtained1 and the effect will prove more satisfactory than if minor sources of illumination are unsuccessfully dealt with4 ,this is especially important in drawing complicated structures such as models of vascular tissues1 embryos1 etc4 ,in cases where many such figures are to occur on one page1 it is highly desirable that the lighting of each should be from the same direction4 ,the use of the half-tone block is now almost universal1 so that it is hardly necessary to mention examples1 more especially as they are hard to judge without seeing the original picture4 ,those in the present book are all of a high quality4 ,excellent examples will also be found in ,tansley's ,types of ,british ,vegetation 7,cambridge1 #aiaa7 and in the ,journal of the ,royal ,horticultural ,society4 ,proofs should be carefully compared with the originals1 particular attention being paid to the rendering of the tones2 as already remarked1 fine etching will clear up a block and will often prove a remedy to flatness4 ,an author will naturally consider whether a photograph is to be reproduced by means of photogravure1 collotype or half-tone4 ,it is impossible to lay down any laws on the subject1 but the following points should be considered4 ,if it is essential to have the reproduction in the text1 a half-tone block must be used2 it must1 however1 be remembered that the paper used for the letterpress may be very unsuited for the printing of half-tones4 ,on the other hand1 if it be immaterial where the picture is placed1 then the relative merits of photogravure1 collotype and kindred processes and half-tone must be weighed4 ,provided that expense need not be considered1 photogravure will1 in the majority of cases1 give the best results2 on the other hand1 if this process is too costly1 then the choice lies between collotype and half-tone4 ,the latter method will often give a result with more contrast as compared with collotype1 whilst collotype will give a truer interpretation of the tones4 ,as has already been remarked1 the best results with half-tone blocks only are to be obtained by the employment of a paper which seemingly has no lasting qualities2 it therefore follows that if the reproduction forms an important record1 the use of collotype is indicated1 since many varieties of good paper are available4 ,as a general rule photo-micrographs are best reproduced by collotype4 ,in order that the respective qualities of these three processes--photogravure1 collotype and half-tone--may be compared1 ,plates #h1 #i1 and #aj have been made from the same photograph1 a view taken by ,dr4 ,f4 ,f4 ,blackman of the ,bouche d',erquy1 a salt marsh in ,brittany1 which was selected chiefly on account of the large number of tones it contains4 ,illustration3 ,,plate #h4 ,photogravure ,illustration3 ,,plate #i4 ,collotype ,illustration3 ,,plate #aj4 ,half ,tone ,these three plates are not entirely comparable1 since the heavy shadows in the right hand bottom portion of the photogravure have been touched up by the engraver4 ,this was not intended by the author1 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 reproduced4 ,it also indicates that for critical work1 when an exact a facsimile as possible is required1 collotype should be used1 for the plate cannot be touched up4 ,with regard to the reproduction of drawings shaded by means of wash or pencil1 the same remarks apply1 with the addition that if it be possible to express what is desired by other means1 suitable for reproduction by line block1 these latter should be employed4 ,to illustrate this point1 ,figures #e1 #f1 and ,plate #aa have been inserted2 all illustrate the vascular skeleton of a fern 7,marattia fraxinea71 the first one is in outline and the second is shaded by lines of varying thickness2 both of these are reproduced by means of the line block1 whilst the third is a reproduction by half-tone of a pencil-shaded drawing4 ,in order to obtain a fair comparison1 the half-tone is reproduced as a plate1 owing to the fact that it would not print satisfactorily on the paper used for the letterpress4 ,illustration3 ,fig4 #e ,illustration3 ,fig4 #f ,illustration3 ,,plate #aa ,,the ,,half-,,tone ,,three ,,colour ,,process4--,this process is much used for colour reproductions of various subjects2 and1 in view of the fact that the best results can only be obtained by the best photography1 the object should1 if possible1 be sent to specialists for reproduction4 ,in many cases1 however1 this is impossible1 e4g41 landscapes and animal and plant portraits amidst their natural surroundings1 so that the scientist1 if unable to make a water colour drawing1 which will give by far the best result1 must make his own negatives4 ,the first thing to do is to purchase a set of colour-filters1 adapted to the colour-correct plates to be used1 from firms who specialize in these matters1 ,messrs4 ,paget or ,messrs4 ,wratten for instance1 and from them the inexperienced should obtain full information regarding exposure1 etc41 for it is essential that the exposure of the negatives should be correlated in order that all may have the same tone-value4 ,the colour-screens1 blue1 green and orange1 are made by dyeing gelatine with suitable stains2 the films are stuck on to perfectly plane glass and are mounted in frames4 ,in practice these screens are usually placed behind the lens1 in which case a special camera is necessary1 or they may be adapted to fit on to the front of the lens4 ,in either case the procedure is the same2 three negatives are taken one after the other through each colour filter1 the exposure being modified in order that the tones in each case may be of equal value4 ,there are thus obtained three negatives which1 of course1 yield positives which look very different one from the other4 ,these prints may be sent to the block makers1 but it is better1 on the whole1 to send the negatives with clear indications as to the colour of each4 ,from each negative there is made by contact a transparency1 and from these positives there are prepared a set of half-tone negatives from which are made the half-tone blocks4 ,the reproductions are made by superposed printing of the three blocks1 yellow being printed first1 then red1 and finally blue 7,plate #ab74 ,illustration3 ,,plate #ab4--,three ,colour ,half ,tone4 ,as indicated above1 it is hardly worth while to make negatives for this process unless the operator is a really skilful or at least an efficient photographer1 and even then the final product may prove unsatisfactory4 ,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 necessary4 ,examples3-- ,bateson3 ,mendel's ,principles of ,heredity1 ,cambridge1 #aiji4 ,church3 ,types of ,floral ,mechanism1 ,oxford1 #aijh4 ,seward3 ,darwin and ,modern ,science1 ,cambridge1 #aiji4 ,,photo-,,mechanical ,,line ,,blocks4--,the photo-mechanical line block1 commonly known as a zinco1 is in a sense the lineal descendant of the wood block4 ,as a means of reproduction the possibilities of line blocks are very great1 for not only is it possible to reproduce by their means all kinds of line drawings1 but also drawings in charcoal and crayon1 provided they be suitably executed on a proper grained surface4 ,in fact1 an artist or draughtsman who has a thorough knowledge of the process and its capabilities can obtain extraordinary results4 ,the process has the further advantage of being both quick and inexpensive1 a few hours only being required to make the finished product4 ,their mode of manufacture is the same in principle as for half-tone blocks2 in the case of the latter1 the method known as the enamel process was described2 in the present instance a different procedure may be dealt with4 ,a photograph of the drawing is taken on a negative1 the wet collodion process being generally followed1 although dry process plates may be used4 ,a highly polished zinc plate is sensitised with bichromate of potash and gelatine1 or by other means1 and1 when dry1 is exposed under the negative4 ,the exposed metal plate is then taken into the dark room and evenly1 but thinly1 coated with etching ink4 ,when the ink is dry1 the plate is developed in water2 the unexposed gelatine1 and with it1 the ink1 will come away1 its removal being helped by the judicious application of a dabber of wet cotton wool4 ,the plate may next be rolled over with an ink which will more stoutly resist the action of the acid than that used in the first inking1 but prior to this it is usual to soak the plate in a mixture of gallic acid1 phosphoric acid and gum4 ,this second rolling up must be carried out as if the plate were for lithographic reproduction2 and1 when dry1 powdered resin may be applied1 in order to make a better acid-resist1 as in the preparation of a lithographic stone4 ,the plate is now etched slightly in a weak solution of nitric acid2 it is then rinsed1 dabbed dry and placed upon a hot plate until the resin has stuck well to the ink4 ,when cool1 the margins1 sides and back are protected from the action of the acid by means of a varnish and the plate is given its first real etch1 which is a very slight one4 ,after rinsing and drying1 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 etching4 ,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 undercut4 ,the plate is then given its second etch1 and this is done with a stronger acid1 after which the sides of the lines are again protected with resinous material in the same way as before4 ,the third etch follows1 after which the metal is thoroughly cleansed from all the ink1 etc4 ,in order to smooth the shoulders of the lines1 the plate is given a finishing etch3 the cleaned plate is warmed and rolled up with hard etching ink2 the metal is then heated until the ink becomes glazed1 and1 when cool1 is placed in the acid bath for the requisite amount of time4 ,if necessary the plate1 after cleaning1 is touched up with a graver1 and the superfluous metal is cut away4 ,finally it is mounted on a block of wood1 and after the corners and sides have been trimmed square1 the block is ready for the press4 ,to illustrate the enormous improvement which may result from the block passing through the hands of a skilful engraver1 two line blocks of a wood engraving by ,riocreux 7see p4 #cf7 have been prepared4 ,fig4 #g is the impression given by the block as ordinarily turned out1 whilst ,fig4 #h is a precisely similar block which has been worked up by an engraver4 ,illustration3 ,fig4 #g ,illustration3 ,fig4 #h ,there are several other methods of making the blocks1 but the principles are the same as in the foregoing process4 ,in examining the proofs it must be remembered that deletions are not the only alterations that can be made in the finished block2 not only can lines be cut away1 or their character altered by removing part of the metal from them1 but additions can be made in reason4 ,for instance1 lines can be added across open spaces1 and if part of the printing surface has been accidentally removed in cutting away the superfluous metal1 the damage can be made good by building up with solder and working on this with the graver4 ,if1 however1 the additions required are at all extensive or complicated1 it is better to have a new block made4 ,inasmuch as scientific illustrations are to describe and explain definite facts1 the drawings must needs be materialistic rather than suggestive2 in other words1 a more or less conventional system must be employed4 ,in making their drawings for reproduction by line blocks1 authors have at their disposal the black line1 the white line1 the black space1 the white space1 the black dot and the white dot1 all of which may be combined in various ways4 ,no tones1 other than black and white1 are available2 if it be desired to represent half-tones1 they must be rendered by the above-mentioned means4 ,in the majority of cases the originals should be made with black ink on white ,bristol board or smooth white paper2 ordinary lead pencil drawings on smooth paper are useless1 and lead pencil1 black crayon or charcoal in combination with grained paper or board should not be employed unless the draughtsman has the requisite skill and knows exactly the limitations of the line block4 ,for all ordinary folk black ink and ,bristol board cannot be improved upon4 ,the drawing may be made first with a soft lead pencil1 using the camera lucida or other optical aids to correct delineation4 ,the pencil lines are then gone over with ink2 for this purpose a good black ink is necessary4 ,wolff's ,indian ink1 ,higgins' waterproof ink and ,steuber's waterproof drawing ink are highly satisfactory1 and there are many others4 ,with regard to pens1 a suitable implement is all-important2 ,gillott's lithographic pens and ,brandauer's ,no4 #eae are recommended4 ,for straight lines of an even thickness a ruling pen is very useful1 and these may be obtained fitted with an adjustment which enables the worker to rule a line of a definite thickness1 e4g41 4#e mm4 and so on4 ,all drawings should be made larger than it is intended the reproduction to be1 for slight inaccuracies1 ragged lines1 and other blemishes will thus appear less obvious4 ,this drawing on a large scale is often a stumbling block1 because the work appears too open and the draughtsman is tempted to put in too much2 this must be avoided1 else the crowded lines may join together in the reduced reproduction4 ,also it must be remembered not to draw too finely1 else the work in parts may disappear entirely in the reproduction4 ,in drawing on an enlarged scale a certain amount of exaggeration may be employed1 in order that when reduced the drawing may not be quite spiritless4 ,when representing a solid object1 such as a plant or an animal1 to shew the external morphology1 it is to be borne in mind that form is the main thing to represent1 and this can be expressed by outline drawing alone4 ,in fact1 more or less primitive methods must be employed1 and better models cannot be followed than the best wood cuts4 ,illustration3 ,fig4 #i4 ,the ,lesser ,celandine 7,ranunculus ,ficaria74 ,by ,r4 ,g4 ,hatton4 7,from ,hatton's ,craftsman's ,handbook74 ,illustration3 ,fig4 #aj4 ,the ,lesser ,celandine4 ,after ,fuchs4 7,from ,hatton's ,craftsman's ,handbook47 ,an examination of figures #aj and #ab will shew that ,fuchs,a attained his object by simple outline drawings2 he never employed local colour1 and shading he used very sparsely indeed1 and then only to give expression to the form of some thick part4 ,fuchs's celandine 7,fig4 #aj7 should be compared with the drawing of the same plant 7,fig4 #i7 by ,r4 ,g4 ,hatton4 ,footnote ,a3 ,the methods followed by the illustrators of the ,herbals may be conveniently studied in ,hatton's ,the ,craftsman's ,plant ,book1 ,london1 #aiji1 and ,arber's ,herbals1 ,cambridge1 #aiab4 ,illustration3 ,fig4 #aa4 ,the ,apple 7,pyrus ,malus74 ,after ,matthiolus4 7,from ,hatton's ,craftsman's ,handbook74 ,the methods of ,matthiolus 7,figs4 #aa and #ac7 were somewhat more advanced1 for he used shading not only to express form but also to give a certain amount of relief4 ,it will be noticed that he shaded by lines which followed the moulding of the parts4 ,the work of ,riocreux 7,fig4 #h7 should also be studied2 it will be observed that he managed to get a very high relief in his drawings by the simple means of straight or curved lines1 according to the shape of the part1 of varying thicknesses4 ,illustration3 ,fig4 #ab4 ,charlock 7,brassica ,sinapis74 ,after ,fuchs4 7,from ,hatton's ,craftsman's ,handbook7 ,there is no necessity for keeping all the lines of even thickness4 ,for instance1 provided the character of the form is not altered1 the outline on the shaded side may be made thicker than on the illuminated side2 also distance can be indicated by the use of thinner lines1 for these1 although really black1 will give the impression of greyness4 ,then again1 a line may be drawn with local increases and decreases in thickness1 as in ordinary writing1 and such lines drawn by a skilled hand can be made to express a marvellous amount of modelling4 ,illustration3 ,fig4 #ac4 ,sea ,lavender 7,statice ,limonium74 ,after ,matthiolus4 7,from ,hatton's ,craftsman's ,handbook47 ,the draughtsman1 however1 is not restricted to lines2 any marks which can be made with a pen and black ink may be employed1 provided they be sufficiently firm and large4 ,the accompanying figure 7#ad7 which is a reduction of an illustration in ,church's ,floral ,mechanisms1 illustrates the use of lines of varying lengths for shading4 ,illustration3 ,fig4 #ad4 ,viola odorata3 ,floral morphology4 ,a reduction of a figure in ,church's ,floral ,mechanisms4 ,in shading1 the effect of shadow may be obtained by increasing the thickness of the lines1 but they must not be drawn too closely together2 on the other hand1 the lighter parts can be represented by thinner lines placed further and further apart1 and the lightest parts by the white of the paper4 ,cross hatching may also be employed 7see ,fig4 #ae71 but the crossed lines must not be too close together1 for otherwise they will tend to thicken in the making of the block and so will print too black4 ,illustration3 ,fig4 #ae4 ,a ,seedling of ,abronia villosa4 ,for very delicate shading and tinting1 stipple may be employed1 but the dots must be quite definite1 sufficiently large to stand reduction1 and not too close together 7,figs4 #ah1 #bh;c1 and #cb74 ,a particularly good example of this method will be found in ,butler's paper on ,allomyces in the ,annals of ,botany1 #aiaa1 vol4 #be4 ,dots have also been employed in ,fig4 #bh;c 7p4 #fi74 ,with regard to local colour2 this may be indicated by shading1 by a white space1 or by a black space4 ,hitherto1 drawing with black ink on white paper alone has been considered1 but the reverse is equally available2 much can be expressed by drawing with white ink on black paper4 ,drawing in white upon a black ground is not frequently attempted1 but an excellent example by ,miss ,janet ,robertson is shewn in figure #af1 which is well worthy of study1 since it illustrates to a nicety some of the means at the disposal of the draughtsman for line blocks4 ,the black surface is best obtained by the use of a waterproof ,indian ink applied with a brush to a white surface1 the drawing being made with a dense white ink1 using a pen or a brush4 ,the white ink may be made by diluting any good opaque white water-colour paint1 or process white may be used4 ,the composition of this should be zinc oxide or baryta1 for these do not darken with age2 the author once used for this purpose a white pigment which proved excellent at the time2 the drawings1 however1 subsequently turned dark brown owing to the fact that the basis of the paint was apparently a compound of silver4 ,illustration3 ,fig4 #af4 ,neuropteris ,heterophylla4 ,a line reproduction of a drawing by ,miss ,janet ,robertson4 ,the top part of the drawing 7,fig4 #af71 shewing the general morphology of the plant1 was drawn with a brush charged with white ink upon a black ground4 ,in the simplest possible way relief has been obtained by representing the leaflets of the nearer fronds by white spaces1 whilst those further away are represented by white outlines4 ,an enlargement of a frond is shewn on the lower part of the picture1 and here the parts are represented in black on a white ground4 ,the leaflets are in black outline and the fruits are made to stand out1 as in the upper part1 by the use of local colour--in this instance black--their shape being indicated by the curve of the higher lights4 ,in brief1 a very effective drawing has been made by the simplest use of the white line1 the white space1 the black line and the black space4 ,illustration3 ,fig4 #ag4 ,fucus volubilis1 var4 ,flexuosus1 a seaweed4 7,from a drawing by ,miss ,baker47 ,this may be compared with figure #ag1 which was drawn by ,miss ,baker2 the method pursued is entirely different to the last1 it being a pure pen and ink drawing on white paper4 ,no local colour has been employed1 and the modelling has been expressed by the lines used for shading which have been made by short strokes with a fine pen4 ,the result is suggestive of an engraving but this was not intentional2 under no circumstances should an attempt be made to imitate in a relief block effects which can only be obtained by intaglio4 ,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 white2 to illustrate this figures #ah-bf have been inserted4 ,illustration3 ,fig4 #ah4 ,the ,larkspur 7,delphinium ajacis74 ,by ,r4 ,g4 ,hatton4 7,hatton1 ,craftsman's ,handbook47 ,illustration3 ,fig4 #ai4 ,hollyhock 7,althaea rosea74 ,by ,r4 ,g4 ,hatton4 7,hatton1 ,craftsman's ,handbook47 ,illustration3 ,fig4 #bj4 ,a ,liverwort 7,lepidozia reptans74 7,evans1 ,annals of ,botany1 #aiab1 vol4 #bf47 ,illustration3 ,fig4 #ba4 ,a ,seedling of ,bruguiera gymnorhiza1 a mangrove4 ,drawn by ,mrs4 ,f4 ,e4 ,fritsch4 7,tansley and ,fritsch1 ,new ,phytologist1 #aije1 vol4 #d47 ,illustration3 ,fig4 #bb ,a diagrammatic sketch by ,mrs4 ,f4 ,e4 ,fritsch of ,rhizophora conjugata1 a mangrove4 7,tansley and ,fritsch1 ,new ,phytologist1 #aije1 vol4 #d47 ,illustration3 ,fig4 #bc ,a shoot of ,acanthus ilicifolia1 a mangrove4 ,drawn by ,mrs4 ,f4 ,e4 ,fritsch4 7,tansley and ,fritsch1 ,new ,phytologist1 #aije1 vol4 #d47 ,illustration3 ,fig4 #bd ,a longitudinal section of a fossil seed1 ,conostoma oblongum4 ,drawn by ,dr4 ,e4 ,j4 ,salisbury4 7,oliver and ,salisbury1 ,annals of ,botany1 #aiaa1 vol4 #be47 ,illustration3 ,fig4 #be ,the ,meadowsweet 7,spiraea ulmaria71 shewing four years' growth4 7,yapp1 ,annals of ,botany1 #aiab1 vol4 #bf474 ,illustration3 ,fig4 #bf4 ,the ,chesil ,bank4 7,oliver1 ,new ,phytologist1 #aiab1 vol4 #aa47 ,,the ,,drawing ,,of ,,microscopic ,,details4 ,questions relating to the drawing of microscope sections may now be dealt with4 ,usually these are drawn in pencil and reproduced by means of lithography2 this is quite wrong1 for in addition to its being an unnecessary expense1 it is also an inconvenience to a reader1 since the figures are necessarily divorced from the letterpress4 ,there are very few histological details which cannot be represented by line blocks1 and with a proper co-operation between the author1 the block maker1 the printer and the publisher1 even the delicacies of karyokinesis could be reproduced in the text4 ,for demonstration purposes1 transverse sections of plant-structures may first be taken4 ,the walls of the various elements may be represented by lines of more or less equal breadth1 but in those cases where the walls are particularly thick1 e4g41 the elements of the wood1 the thickening may be represented by an additional line4 ,this is seen in ,fig4 #bg1 in which it will be noticed that the middle lamellae of the wood-elements are represented by black lines4 ,illustration3 ,fig4 #bg4 7,from ,butler's paper on ,gummosis of ,prunus and ,citrus4 ,annals of ,botany1 #aiaa1 ,vol4 #be74 ,this is a particularly good drawing1 but1 unfortunately1 it has been over reduced4 ,on the other hand1 the various tissues may be represented by lines of varying breadths1 the thickest walled cells having the same double contour as in the above1 but with the addition of local colour in the shape of diagonal shading4 ,this is not uncommonly found in papers dealing with the anatomy of plants by ,french authors2 it is illustrated in ,figure #bh a4 ,if preferred1 such thick-walled elements may be entirely represented by thick black lines as in ,figure #bh;b1 and when such cells are relatively few in number1 this method has much to recommend it since a greater relief is obtained4 ,illustration3 ,fig4 #bh a b c ,a transverse section to shew the vascular cylinder of the root of the spinach1 c is somewhat older than a and b4 ,finally1 an attempt may be made to draw in a more detailed fashion as in ,figure #bh;c4 ,here the thickness of the cells of the wood is represented by broad black lines1 the middle lamellae being left white4 ,the lines marking the boundaries of the other cells vary slightly in thickness1 but this is to a great extent masked by the representation of the cell contents1 which consist entirely of dots in the case of the protoplasm1 whilst the nuclei are represented by dark ovals--black relieved with small white areas4 ,by varying the size of the dots and their distance apart1 varying densities can be indicated4 ,it has been mentioned above that it is possible to reproduce fine detail by means of the line block2 this is illustrated in ,figs4 #bi and #cj4 ,illustration3 ,fig4 #bi ,fig4 #bi1 which illustrates a stage in the division of a nucleus1 was drawn with black crayon on a rough-grained piece of ,whatman's water-colour paper4 ,the cytologist will1 doubtless1 criticize its coarseness1 but it may be mentioned that the roughest paper at hand was designedly employed in order to illustrate the point raised4 ,that a finer grained paper will give more delicate results is shewn by ,fig4 #cj1 which is a reproduction of a drawing1 kindly lent by ,dr4 ,w4 ,g4 ,ridewood1 made with ordinary lead pencil on grained ,bristol board4 ,its delicacy is obvious1 and at first sight it could easily be mistaken for a lithograph4,a ,footnote ,a3 ,many similar examples will be found in ,ridewood's memoir ,on the ,cranial ,osteology of the ,clupeoid ,fishes1 ,proc4 ,zoo4 ,soc41 ,lond41 #aijd1 vol4 #aa1 p4 #ddh4 ,illustration3 ,fig4 #cj ,a half-tone can be put on to a line block during its manufacture4 ,all that the draughtsman has to do1 is to indicate by blue pencil lines those parts on which he requires the dots1 which give the half-tone1 to be placed1 and to select the pattern of the stipple he desires to be used4 ,the result may appear somewhat mechanical since the dots are regularly arranged1 but a drawing sometimes may be considerably improved by this means if used with judgment4 ,it is frequently employed in representing drapery1 and many examples may be found on those pages of newspapers devoted to ladies' dress 7,fig4 #ca2 see also ,fig4 #cb74 ,illustration3 ,fig4 #ca4 ,after a water-colour design by ,miss ,winifred ,pearse4 ,,the ,,drawing ,,of ,,diagrams ,,and ,,apparatus4 ,much valuable information may be conveyed by diagrams2 in fact1 these could be used more freely than they are4 ,illustration3 ,fig4 #cb ,the principles to be borne in mind are the same as for other ink drawings4 ,they should always be drawn upon an enlarged scale1 and with as little detail as possible1 which generally should be indicated in the most conventional ways--dots1 black spaces1 lines1 and so on 7,figures #cc and #cd74 ,the main thing to be aimed at is clearness1 so that it is often necessary to sacrifice true relative proportions in order to gain this end 7,fig4 #cd74 ,illustration3 ,fig4 #cc4 ,a diagram by ,mr4 ,e4 ,lee4 7,annals of ,botany1 #aiaa1 vol4 #be47 ,illustration3 ,fig4 #cd ,a ,diagram from the ,annals of ,botany1 #aiab1 ,vol4 #bf4 ,in certain cases it is possible to combine detail and diagram in one drawing2 this is shewn in ,fig4 #cb1 taken from ,dr4 ,ridewood's admirably illustrated memoir on the ,gills of ,lamellibranchiata 7,transactions of the ,royal ,society of ,london1 ,b4 vol4 #aie1 #aijc74 ,the shading employed was either done by the draughtsman 7at ch and in the cells with irregularly arranged dots71 or else was put on the block during its manufacture 7af74 ,if a lens be used1 the difference will at once be obvious4 ,the finished drawing should be bold and neat1 and all lettering should be very clear4 ,if several figures are included in one diagram they may be separated one from the other by ruled lines1 and in no case should one tier of figures--taking the frames as the boundaries--unevenly overlap another tier1 otherwise the diagram1 to use an expressive phrase1 will look like a pig with one ear4 ,under the heading of diagrams must be included the representation of apparatus4 ,there are two ways of drawing apparatus2 the objects may be drawn as a study in still life1 as1 for example1 in many of the figures illustrating ,deschanel's ,natural ,philosophy 7,london1 #ahij7 or they may be represented in a purely conventional fashion4 ,the latter is the better way1 and it is preferable to draw for the most part in section in order that all connections1 inlets1 outlets1 etc41 may be clearly shewn4 ,a study of a good example is infinitely better than a written description1 wherefore ,figure #ce has been inserted4 ,illustration3 ,fig4 #ce ,it will be observed that all glass vessels and tubing are represented in section1 and in the thermometers1 the fine capillary bores are represented by a single line in each case2 corks by diagonal shading2 wood by lines in imitation of its grain2 metal parts by vertical shading or dead black2 more or less still liquids by a series of lines broken below and continuous at the surface1 and gradually becoming closer and closer together towards the surface4 ,mercury1 on the other hand1 may be indicated by dead black relieved by a few white lines to represent its reflecting surface1 also its free surface may be drawn convex4 ,finally thumb screws may be shewn by a combination of black areas and vertical shading4 ,these conventionalities need not all be followed2 for instance1 rubber connexions may be indicated by broad black lines and wood by diagonal shading4 ,the drawing should be very bold and the different parts clearly and freely indicated by writing or printing4 ,,the ,,drawing ,,of ,,maps4 ,in the drawing of maps for reproduction by the line block process1 if an existing map serves the purpose1 a tracing may be made in ink on translucent linen4 ,if1 on the other hand1 the author has to make his own map1 the problem becomes more difficult4 ,for the obtaining of the data for map making information must be sought for elsewhere1 since we are only concerned in the preparation of the map for publication4 ,and as regards this1 but few general rules can be laid down since the character of maps is so diverse4 ,the amount of detail in the physical features represented depends to a great extent upon the scale4 ,thus streams of a greater breadth than1 say1 #aj feet1 may in large scale maps be represented by double lines1 whilst no stream less than #b feet in breadth will be shewn in low scale maps4 ,illustration3 ,fig4 #cf a ,contoured4 b ,spot-levels4 c ,layered4 ,these three figures illustrate in three different ways the varying levels of a piece of ground surveyed by ,prof4 ,f4 ,w4 ,oliver and ,mr4 ,a4 ,g4 ,tansley4 ,the indication of hills is always a problem2 the most satisfactory way is by the drawing of contours 7,figure #cf;a71 and this whenever possible should be followed1 since it is scientifically the most correct method1 inasmuch as when properly drawn the form of the hill is shewn exactly2 further1 contours obscure the detail to a much less extent than does shading1 and but little artistic talent is required to draw them4 ,if1 however1 contouring be impossible1 the various heights above the datum may be shewn by spot levels 7,figure #cf;b7 or the relative levels may be shewn by layers2 that is to say1 by a system of shading each kind of which indicates a certain level4 ,thus dots may be used for all parts not more than #ajj feet above sea level1 vertical lines for regions between #ajj and #bjj feet1 horizontal lines for parts between #bjj and #cjj feet1 and so on 7,figure #cf;c74 ,it is obvious that this method cannot be pursued if vegetation also is to be shewn4 ,the last choice is to represent the hill by shading in much the same way as many of us did when children2 the method referred to was known as herring bones or hairy caterpillars4 ,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 apart4 ,if geological strata are to be represented1 the accepted symbols should be used2 if the map is intended to represent the distribution of soils1 convenient signs may be employed1 e4g41 large dots for shingle or gravels1 small dots for sand1 black areas for clay1 and so on2 finally1 if the distribution of plants or of animals is to be shewn1 symbols again may be employed4 ,these1 however1 must be quite simple and as far as possible give an idea of the organism represented4 ,this1 in the case of animals1 may be a difficulty1 but1 with regard to plants1 simple signs are easily inserted which give a very good idea of the plant it is intended to represent4 ,many of the signs used by the ,ordnance ,survey are ready to hand1 and these can often be used to designate plant associations4 ,the delimitation of areas should always be clearly shewn1 and all names should be very clearly printed indeed1 and if they must be placed on a dark portion of the map1 they should have a good white border around them4 ,the north should always be indicated4 ,this may be done by drawing in its proper position a representation of a compass or merely an arrow pointing to the north4 ,unless otherwise stated1 the arrow is assumed to point to the magnetic north1 and if no north be actually shewn it is taken for granted by an intelligent reader that one of the vertical sides is a true north and south line1 with the north at the top4 ,finally1 under no circumstances should a scale be omitted--it is the first thing a reader should look for4 ,for a map to look well two things are all-important1 neatness and clearness2 both of these may nearly always be secured by drawing on a large scale1 bearing in mind what has been said about crowding the detail1 etc41 and carefully considering how much reduction the original can stand4 ,this last point is of vital importance1 for an over-reduced map is an abomination2 we have seen really good maps absolutely ruined by this stupid error4 ,the inexperienced author should study the methods pursued by ,prof4 ,yapp in ,figure #cg4 ,for comparison1 the simpler way adopted by ,mr4 ,wilson may be studied 7,annals of ,botany1 #aiaa1 ,vol4 #be74 ,illustration3 ,figure #cg4 ,a ,map of the ,fenland by ,prof4 ,yapp4 7,new ,phytologist1 #aijh1 ,vol4 #g7 ,,graphs ,,or ,,curves4 ,simple though it be1 the plotting of a curve for reproduction requires thought and care4 ,in the first instance1 the curve is drawn on squared paper1 and the question naturally arises--,to what extent are the squares to be represented8 ,if it be desired to reproduce all the lines1 say the paper is ruled in millimetres1 a half-tone may be employed1 or all these lines can be ruled over in black ink where the reproduction by line block is possible4 ,it is1 however1 seldom necessary to represent all the smallest squares2 it will generally be found that the centimetre squares are sufficient4 ,if the original be plotted on paper which is ruled in pale blue1 it can be reproduced by line block without re-drawing1 since the blue will photograph as white with the plates commonly used2 all the essential lines and curves must1 of course1 be in black4 ,if1 however1 the rulings of the squared paper are in red1 yellow1 or dark blue1 a tracing must be made4 ,the horizontal and vertical sides should be ruled with a broad black line1 but the internal intersecting lines should be much thinner4 ,the actual curve may be in a continuous line if one only be shewn on the graph2 if more are drawn1 then each must be different1 the obvious variations being the thick continuous line ---- the thin continuous line ----1 dashes either thick or thin ---- ---- ----1 dots 4 4 4 4 4 1 and finally combinations of dots and dashes ---- 4 ---- 4 ---- 4 ,owing to the difficulty which some experience in drawing freehand a continuous line1 the plot should be made twice the linear size of the intended reproduction4 ,a good rule to follow in drawing lines is to keep the eye fixed on the point where the line is to end1 the hand will then guide the pen in the right path1 especially after a little practice4 ,in many cases the ruler may be used1 not only for straight but also for curved lines1 for good curve rules may be purchased4 ,in order that the figure may look neat1 the lines should be of an even thickness throughout their length2 this is easily accomplished by means of a ruling pen4 ,it has been stated above that ,bristol board is the best material to use for the making of drawings for line blocks2 other materials may1 however1 be employed1 although they are not so nice to work upon4 ,for instance1 it may be necessary to reproduce a map2 this1 as has already been mentioned1 may be conveniently done by pinning over the map a sheet of pale blue tracing linen1 and tracing the map on this with ,indian ink4 ,the fact that the linen is blue does not matter1 for it will photograph as if it were white4 ,then again1 many subjects may be of so complicated a nature as to be beyond the skill of the author to draw4 ,in such a case a good plan is to take a photograph of the object and make a positive on smooth bromide paper1 which need only be developed sufficiently far to give a print which just shows the features4 ,the print1 when dry1 can then be worked on with fixed ,indian ink4 ,the finished drawing1 when quite dry1 may be immersed in any solution which will dissolve out the silver2 a solution of iodine in potassium iodide answers sufficiently well4 ,the print will turn very dark1 but it must be allowed to remain in the bath until all the silver has dissolved2 it is then removed1 rinsed under the tap and placed in an ordinary fixing bath of hyposulphite of soda4 ,all the colouration will be quickly removed so that the ink drawing will stand out well against the white paper4 ,all that it now requires is a thorough washing in water2 when dry it may be touched up and then placed under pressure in order to make it quite flat4,a ,footnote ,a3 ,the chief disadvantage of iodine solution is its slowness of action2 the following methods are much quicker4 7a7 ,to a solution of #d oz4 of hyposulphite of soda in one pint of water1 add a #aj per cent4 aqueous solution of potassium ferricyanide until the mixture is lemon coloured4 ,when the silver image has quite disappeared1 wash the print thoroughly in water4 ,since the mixture does not keep1 the ferricyanide solution should be added to the hyposulphite solution immediately before use4 7b7 ,mix #abe ccs4 of a #aj per cent4 alcoholic solution of iodine with #ba ccs4 of a #aj per cent4 aqueous solution of potassium cyanide1 add to the mixture #a litre of water4 ,when the image has disappeared1 which will be in less than a minute1 wash for five minutes in water and dry4 ,this method of drawing over photographic prints will often save a considerable amount of time4 ,for instance1 it may be desired to reproduce a consecutive series of drawings to illustrate the microscopic structure of the subject4 ,the ordinary way of doing this is to make camera lucida drawings of the sections1 which is a lengthy and tiresome process2 a photograph of each section will take much less time and will give quite as good results4 ,before sending any line drawings to press they should be carefully examined2 pencil marks may be rubbed out1 lines touched up1 unnecessary lines removed by painting them out with white or black ink according to the background1 and1 finally1 a frame ruled around1 if necessary4 ,the amount of reduction1 which should be marked clearly on the margin1 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 may1 moreover1 appear spiritless4 ,it must also be remembered that a reduction of1 say1 #a_/b linear means that the reproduction will be a quarter the area of the original4 ,the best way to indicate the reduction required is to draw a vertical or horizontal line1 parallel to a side or the base of the picture1 of the exact length2 or1 the line may be roughly drawn and its length indicated by figures thus ------------#b-a_/b--------- 4 ,the question arises as to when line drawings for reproduction by the zinc block should be employed4 ,the answer is1 ,whenever possible4 ,the advantages to a reader of having the illustrations in the text has already been commented upon4 ,it is about the only method commonly employed in which practically everything depends on the draughtsman2 the author thus exercises the greatest control4 ,finally the fact that it is very inexpensive will appeal to editors and publishers4 ,as a matter of curiosity1 the present writer picked out at random a recent volume of a scientific journal to examine the illustrations2 although there were a number of text figures1 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 text4 ,a more detailed inspection of the plates was therefore made1 with the result that nearly #bjj figures were found which with the minimum amount of alteration--merely drawing in ink instead of pencil in the majority of cases1 and leaving out unnecessary shading in the others--could have been reproduced by line blocks4 ,if this had been done1 a saving of over #bj per cent4 could have been effected on the plates4 ,some of this would1 of course1 have been absorbed in the making of zincos1 but not much1 since line blocks of excellent quality can be obtained for #b-a_/b;d4 and #c;d4 per square inch4 ,the above relates only to the most obvious examples2 the saving in plates would have been enormous if the authors had drawn for the line process4 ,,the ,,swelled ,,gelatine ,,process4 ,from the foregoing account of the line-block it may1 perhaps1 be thought that a drawing shewing the finest detail cannot be reproduced in the text by a relief block made by photo-chemical means4 ,this is not the case2 the swelled gelatine process is such that at its best the very finest work can be so reproduced4 ,the method is not extensively used1 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 block4 ,this1 however1 should not militate against its use1 for the increased cost is but very little1 and the longer time in making1 say two days1 should not be of any consequence in a monthly or quarterly periodical4 ,the great point in its favour is its great fidelity as compared with the ordinary photo-chemical relief blocks3 for instance1 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 thicken2 hence1 on printing1 the white spaces1 instead of being sharply cut and diamond-shaped1 are rounded4 ,this will not occur in a good block made by the swelled gelatine method4 ,further1 the process does not restrict the draughtsman to dead black ink2 the drawings may be made in pencil1 crayon1 or in ordinary writing ink3 it is even claimed that wash drawings and photographs can be reproduced satisfactorily by this method4 ,in the case of pencil drawings1 the best results will be given when the surface of the paper used by the draughtsman is slightly rough2 a pencil drawing on ,bristol board1 for example1 will not be so well reproduced as one on ordinary smooth drawing paper4 ,in brief1 the process is as follows3 a photographic negative of the drawing is made1 and under it is exposed a bichromate gelatine plate4 ,this plate is then developed in water4 ,as already described1 the gelatine will swell up in proportion to the amount of light to which it was exposed4 ,the positive thus obtained will be in relief1 the high lights being at a higher level than the shadows4 ,a wax mould of the gelatine positive is then taken1 covered with a thin layer of plumbago and electrically covered with copper4 ,the casting so obtained is built up with metal and then mounted on wood in the same way as a zinco or a half-tone4 ,the capabilities of the process may be judged by a study of ,fig4 #ch1 which is an extremely faithful reproduction of a lithograph1 by ,s4 ,prout1 by the swelled gelatine process4 ,illustration3 ,fig4 #ch4 ,a ,lithograph by ,s4 ,prout reproduced by the swelled gelatine process4 ,illustration ,,cost ,,relative ,,cost ,,of ,,blocks ,,and ,,plates ,the question of cost is one of very great difficulty2 in all probability no two firms will agree in their quotations for different kinds of work1 and the reason for this lies in the large number of factors involved1 many of which are very difficult to compute exactly4 ,with respect to line engravings1 etching1 mezzotint1 wood cuts and wood engravings1 it is impossible to give any idea of the cost4 ,it depends entirely on the complexity of the subject and the artist employed4 ,as regards lithographic processes for reproduction in one colour the cost varies with the nature of the work4 ,if an artist be commissioned to make an autolithograph1 the fee would be agreed upon beforehand4 ,photolithography and collotype1 on the other hand1 are processes which do not require the hand of an artist1 and these methods of reproduction are relatively inexpensive4 ,the price quoted by the lithographer or collotyper is for printing so many copies1 hence the relative cost per copy depends upon the run and on the quality of the paper used4 ,lithography is cheaper than collotype2 but if several illustrations are sent at the same time to be reproduced by collotype1 the cost for each would be less than if sent separately4 ,in chromolithography a separate stone is necessary for each colour1 hence the cost depends upon the number of stones used1 and as several may be necessary to obtain a first-rate reproduction1 it is obvious that the process may prove very expensive4 ,turning to photomechanical processes1 the prices vary according to the grade of work required--the best possible1 good1 and1 lastly1 cheap work4 ,by best possible is meant the best that can be made under existing conditions1 the price being immaterial2 in good work the cost will be a limiting but not a preponderating factor1 hence the work will be open to criticism2 finally1 in cheap work1 the price is all important1 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 original4 ,it is obvious that in the last two cases the quality of the work will depend upon the agreed price1 whilst in the first case the cost will depend on the amount of time and skill required4 ,it is obvious1 therefore1 that a comparison of cost cannot be made between these grades2 it is1 however1 possible to draw up a scale of relative cost of the processes under consideration for work of the same grade4 ,in the table given below1 ,a represents the best possible work1 ,b indicates good work1 and ,c stands for cheap work4 ,since the line block is the least expensive it is taken as the unit of price2 that is to say1 if a line block costs #c;d4 per square inch the cost of half tone1 three colour half tone and photogravure would be #g-a_/d;d41 #cs41 and #as4 #b-a_/b;d4 respectively4 ,a ,b ,c ,line #a #a #a ,half tone and swelled gelatine #b-a_/b #b-a_/d #b ,half tone three colour 7three plates required7 #i #ab #aj-a_/b ,photogravure #d-a_/b #d-c_/d #e ,it must not be thought that if the area of a block is #c square inches1 the cost will1 therefore1 be #i;d4 ,there is1 for obvious reasons1 a minimum size at which the block or plate is charged although it may be smaller4 ,these minima vary2 in general terms they may be taken as #ab inches for line1 half tone and swelled gelatine blocks1 and #bj inches for half tone three colour blocks and photogravure plates4 ,the measurements are the areas of the etched surface1 the actual plate or block may be larger1 but for this margin no charge is made4 ,with regard to cost of printing1 nothing need be said about blocks which are set up with the type1 namely line1 swelled gelatine and coarse half tone blocks4 ,the price of printing fine half tones and three colour blocks depends upon the quality of the paper used and the fineness of the work4 ,photogravure plates must be hand printed 7photogravure printing on rotary machines is not considered here71 and skill is required2 for ordinary printing on good plate paper the price would be #ajs4 to #abs4 #f;d4 per hundred copies1 whilst for ,india printing the cost would be about #bes4 for the same number4 ,,literature ,barnes3 ,illustrating ,botanical ,papers1 ,botanical ,gazette1 ,vol4 #dc1 #aijg4 ,bock3 ,zincography1 ,london1 #aiaj4 ,cumming3 ,handbook of ,lithography1 ,london1 #aijd4 ,cundall3 ,a ,brief ,history of ,wood-,engraving from its ,invention1 ,london1 #ahie4 ,gamble3 ,line ,photo-engraving1 ,london1 n4d4 ,hamerton3 ,drawing and ,engraving1 ,london1 #ahib4 ,etching and ,etchers1 ,london1 #ahhj4 ,the ,graphic ,arts1 ,london1 #ahhb4 ,pennell3 ,lithography and ,lithographers1 ,london4 ,richmond3 ,grammar of ,lithography1 ,london1 #aiji4 ,robertson3 ,the ,art of ,etching1 ,london1 #ahhe4 ,verfasser3 ,the ,half-tone ,process1 ,london1 n4d4 ,wilkinson3 ,photo-mechanical ,processes1 ,london1 n4d4 99 99 99 99 99 ,transcriber's ,note ,some extraneous ,headings on otherwise blank pages have been removed4 ,each ,footnote has been indented and placed beneath the paragraph to which it refers4 ,the ,plates1 which were on un-numbered pages1 and some of the ,figures1 have been moved to 7usually7 below the paragraphs which first refer to them4 page #ce3 'revelant' corrected to 'relevant' 444 ,see also the relevant works cited under ,literature page #ij3 ,the ,table of ,costings does not appear to make sense1 but has been left as in the original4 ,hyphenation is not consistent in this book4