August, IQll. 



KNOWLEDGE. 



323 



and Lincolnshire for a century there was nothing to hinder it 

 following the coast line to Scotland. 



These observations have received immediate point by tlie 

 publication in the new lumiber of the Annals of Scottish 

 Xiitiiral History l.\o. 79. July. 1911, page 1321 of a short 

 paper by Misses E. \'. Baxter and L. J. Rintoul announcing 

 that thev had secured a single specimen of the Nightingale on 

 the Isle of May, Firth of Forth, on 9th May, 1911. This is an 

 addition to the avi-fauna of Scotland, and to the rarities and 

 valuable records which careful and continuous watching of 

 the Isle of May has yielded to the writers .above-named. 

 Following recent nomenclature they call the bird the Southern 

 Nightingale [Liiscinia mcgarhynchos nicgarliynclios = 

 Daiilicis tiiscinia of Saunders and other authors!. 



^Our readers are invited to send in any observations that 

 they may be able to make upon the distribution of the 

 Nightingale.] 



XKE BLACK GAME VERMIN ?— The answer to this 

 question, like many others, depends largely upon the point of 

 view and upon personal predilections, and sportsmen may 

 probably not agree with the judgment given in the recently 

 pubhshed " Forest Survey of Glen Mor " (1911), by Lord Lovat 

 and Captain Stirling of Keir. This work contains recom- 

 mendations for the treatment of grouse and low game 

 shooting from the point of view of the forester and timber- 

 grower, and makes the proposal to reduce Black Game from 

 the status of game birds to that of forest vermin. With this 

 finding, all who have had experience of the depredations of the 

 species will, we believe, be found ready to agree, with but 

 little reluctance. 



BIRDS BREEDING IN THE LONDON ZOOLOGICAL 

 G.ARDENS. — This has been a good season and about one 

 hundred and fifty had already bred by the beginning of July, 

 although, for foreign species, the season was not more than 

 half over then. The expectations and prospects were that this 

 number would be considerably augmented. The Wigeon does 

 not commonly breed in confinement, but of this nati%e British 

 species there were fifteen well-grown ducklings, and another 

 brood was looked for. Amongst the young Gulls were three 

 interesting hybrids, the produce of the Lesser Black- B;icked 

 and the Common Gull. 



ABUNDANCE OF THE COMMON SWIFT 

 iCYPSELL'S APUS). — It is far from easy to compare the 

 numbers of any of our commonly seen birds, season with 

 season, with any approach to accuracy. In any summer the 

 Common Swift is an abundant bird in the neighbourhood of 

 London, but this year it seems to be present in larger numbers 

 than usual, judging by the swarms which are now disporting 

 themselves in the district on the Middlesex and Hertfordshire 

 borders. In the neighbourhood of Bushey, for instance, a 

 glance around any morning or evening shows some dozens 

 within sight in the air. To attempt to estimate the numbers 

 would be futile ; but it may be worth remarking that, one day 

 in the month of May three years ago, 190S, the writer spent a 

 considerable time in attempting to count the numbers of a large 

 gathering of Swifts, hawking over the surface of the Brent 

 Reservoir, Middlesex, and approximately set them down as 

 some seven hundred or eight hundred birds, 



BIRDS IN THE ELEVENTH EDITION OF THE 

 '•ENCYCLOPAEDIA BRITANNICA" 119111.— This work 

 contains reprints of the series of articles contributed by the 

 late Professor A. Newton to the ninth edition with some 

 small alterations. These articles are assuredly classics 

 in ornithological literature, but it is to be regretted that the 

 new edition does not contain the supplementary matter ^^■hich 

 Professor Newton himself included in republishing them in his 

 great " Dictionary of Birds" (1S93-6). This leaves the last- 

 named work, and not the new edition of the '" Encyclopaedia" 

 as the final and more complete authority on the birds included. 

 The " Encyclopaedia," however, contains fresh ornithological 

 writings in such articles as those on the general subject 

 " Bird," and on " Egg," " Feather." and so on. 



PHOT(3GRAPiIY. 



By C. E. Kenneth Mees, D.Sc. 



TRI-COLOK PRINTING INKS.— To the Process Photo- 

 gram for July, Mr. A. J. Bull contributes an excellent article 

 on the rendering of greens in three-colour work, in which he 

 directs attention to the fact that the difficulties mot in repro- 

 ducing greens by the three-colour process, are mainly due to 

 the fact that even the best blue inks used for that process 

 have but a low reflecting power for green light. In a totally 

 different article, that by Sir Harry Johnston on the art of 

 painting, in the Westminster Gazette, we find another 

 indictment of three-colour printing inks from the point of 

 view of the artist. He writes : — " Fortunately for painters, a 

 stereotyped reproduction in colour is hampered at the present 

 day by the miserable quality of the inks and pigments used by 

 all colour printers (except here and there in Germany, Austria, 

 and France)." This would seem to imply that Sir Harry 

 Johnston considers that the printers are to blame for the poor 

 quality of the inks and pigments that they select, but it would 

 be interesting to know on what grounds he makes exception in 

 favour of certain printers in Germany, .\ustria, and France. 

 It may be true that there are printers in those countries who 

 produce better results than those produced in England or the 

 United States, — the present w-riter does not possess the 

 necessary knowledge to gi\e an opinion upon the subject, but 

 he doubts very gravely whether, if the results produced are 

 superior, the effect is to be ascribed to the use of better inks. 

 Colour-printing inks are chiefly made in large quantities by 

 big firms, and any ink that is on the market can be obtained 

 by any printer who desires it. nor does the price of an ink 

 necessarily increase with its suitability for three-colour work. 



The real difficulty in the obtaining of more suitable inks for 

 the three-colour process lies in the wide separation between 

 the user of the inks and the original producer of the colour. 

 The user of the ink is the printer, but the colour is largely 

 chosen for him by the photo-engraver who makes the blocks, 

 and he, in his turn, is limited by the inks that he can obtain 

 from the maker, who is again limited by the lakes which the 

 dye works can supply. It is not to be expected that these 

 various commercial undertakings will all fully understand the 

 theory of the three-colour process, the only one of them who 

 actually requires the knowledge in e\ery-day work being the 

 block-maker, and hence, while most photo-engravers now 

 understand what inks they require, ink makers, as a rule, will 

 tell you frankly that they supply any colour of ink for which 

 they can obtain satisfactory lakes, and leave the choice of the 

 inks to the engraver. A visit some years ago to a great dye 

 works containing a section devoted to the preparation of lakes 

 for thiee-colour printing opened the writer's eyes to the fact 

 that the scientific chemists in charge of that section, had not 

 the least knowledge of the theory of the three-colour process, 

 and had not taken any steps to attempt to obtain permanent 

 colours of the right shade, the colours which the firm 

 reconmiended for the production of three-colour printing inks 

 being entirely unsuited to the purpose, and being selected 

 simply for their printing qualities, with \'ery little reference to 

 theoretical requirements as to colour. It is not too much to 

 say that there are no inks in existence which are both permanent 

 and of the right shade for three-colour printing, and the reason 

 for this is undoubtedly that the dye works have not yet produced 

 permanent lakes of the right shade. There is, of course, no 

 difficulty with the yellow ink, but the red ink always reflects 

 far too little blue, while the blue ink reflects only a small pro- 

 portion of the required amount of green. There are dyes 

 which are nearly of the right shade : some of the acid rhoda- 

 mines, for instance, are nearly the right shade of magenta, and 

 fast green blue shade, or patent blue would make a satisfactory 

 blue ink, but apparently the lakes which can be produced from 

 these dyes are not fast to light, so that for improvement in 

 colour-printing, as in so many other things, we must look to the 

 scientific chemist at the base rather than to the ink-maker or 

 printer who are dependent upon him for their materials. 



THE DEVELOPMENT OF QUANTITIES 

 OF N E G A r I \' E S . — When a large number of exposed 



