556 



NA TURE 



[October 4, 1900 



The additions to the Zoological Society's Gardens during the 

 past week include two Macaque Monkeys {Macacus cynotnolgus) 

 from India, presented respectively by Mrs. Woods and Mrs. 

 Sassoon; a Plantain Squirrel {Sciurus plantani) from Java, 

 a Vulpine Phalanger {Trichosurus vulpecula) from Australia, 

 presented by Mrs. A. Jeffrey ; a Ground Hornbill (Bucorvus 

 abyssinicus), a Bell's Cinixys {Cinixys belliana) from West 

 Africa, presented by Mr. Henry Strachan ; a Peregrine Falcon 

 {Fako peregrinus), European, presented by Mr. W. R. Bryden ; 

 a Brazilian Tapir (Tapirus americanus), two Snowy Egrets 

 {Ardea candidissima), six Ring-necked Lizards {Tropidurus 

 iorquattis), three Surinam Lizards {Ameiva siirinamensis), a 



Lizard {Crocodilurus lacertinus), two Tuberculated Iguanas 



{Iguana tiiberculata), six Giant Toads (Bufo marinus) from 

 Para, presented by Captain A. Pam ; a Vivacious Snake 

 {Tarbophis fallax), European, presented by Mr. W. H. St. 

 Quintin ; a Spix's Macaw [Cyanopsiltacus spixi) from Brazil, a 

 Large Grieved Tortoise {Podocnemis expansa) from the 

 Amazons, six Florida Tortoises {Tesludo polyphemus) from 

 North America, four Elegant Snakes ( Tropidonotus ordinahis 

 infernalis), four Couch's Snakes ( Tropidonotus ordinatus couchi) 

 from California, deposited ; a Bristly Ground Squirrel {Xerus 

 setosus) from South Africa, a Pink-headed Duck (Rkodonessa 

 caryophyllacea) from India, purchased. 



OUR ASTRONOMICAL COLUMN 



Ephemeris for Observations of Eros : — 



THE ROYAL PHOTOGRAPHIC SOCIETY'S 

 EXHIBITION. 



T^HE Royal Photographic Society hold their annual exhibition 

 -*■ this year in the New Gallery, Regent Street, instead of, 

 as heretofore, at the Water Colour Society's Gallery in Pall 

 Mall. The result of the change to the larger galleries is 

 certainly a matter for congratulation, because the very restricted 

 accommodation of previous years crowded out professional and 

 trade work, and gave very little space indeed for the exhibition 

 of scientific and technical photography. This year, if any 

 branch of photography is not represented, it is because of other 

 difficulties than want of space. The only notable omission 

 that occurs to us is that of cinematography, and this is accounted 

 for by the very stringent regulations now enforced making a 

 practical demonstration impossible. 



The pictorial section occupies about as much of the walls 

 as usual, and the greater part of the remaining space is taken up 

 by professional and trade work, and apparatus exhibits, many 

 of which, however, are not entirely devoid of scientific interest. 

 But upstairs, in the gallery that runs round the central hall, 

 there will be found a very excellent collection of " scientific, 

 technical and photomechanical exhibits." 



The Royal Observatory, Greenwich, contribute some of their 

 most recent work with the 30-inch reflector, the 26-inch 

 Thompson photographic refractor and other instruments. The 

 photograph of the great nebula in Orion, taken last December, 

 appears to be especially noteworthy. Two plates of the planet 

 Eros are shown. A photograph of \ Ursse Majoris, taken with 

 the 28-inch equatorial, the object-glass being corrected for 

 photography by the separation of the lenses and reversal of the 

 crown lens, as proposed by Sir G. G. Stokes, testifies to the 

 value of this method of correction. Examples of work with the 

 occulting shutter and several recent eclipse photographs will be 



NO. 1 6 14, VOL. 62] 



examined with interest. Among several other astronomical 

 photographs may be mentioned a paper enlargement of very 

 considerable dimensions of the transit of Venus in 1882, by 

 Prof. David P. Todd, and a series of photographs by the Rev. 

 John M. Bacon illustrating his balloon ascent to search for the 

 Leonids last November. 



There are several contributions of photomicrographs. As 

 examples of skill in this direction, the series by Mr. E. M. 

 Nelson, of diatoms, exhibited by the Royal Microscopical 

 Society, will probably attract the most attention. The natural 

 history and biological photographs of all kinds are too numerous 

 to refer to in detail. As notable illustrations of the value of a 

 series of photographs illustrating biological changes, the sixteen 

 lantern slides, by Mr. Martin F. Woodward, from his photo- 

 micrographs, showing the fertilisation and segmentation of the 

 egg of Ascaris megalocephala, and a frame of photographs, by 

 Mr. Edgar Scamell, showing the different stages in the growth 

 of a nasturtium, will well repay careful study. The photographs 

 in the latter series are so numerous that they would almost serve 

 to illustrate the growth of the plant as a "living picture" by 

 means of a cinematograph. It is very usual to slow down a 

 rapid movement that its details may be recognised, and there is 

 doubtless much to be learnt from the representation in a few 

 seconds of changes that naturally require days or even weeks for 

 their completion. 



The applications of photography in many other directions are 

 well illustrated. The automatic recording of the variations of 

 scientific instruments, spectroscopic work, surveying, mining, 

 engineering, the production of metal reliefs, are a few of the 

 subjects that occur to us. Dr. W. J. Russell shows prints to 

 illustrate the photographic activity of the radiations from " the 

 metals radium and polonium," and also from uranium salts, 

 which he finds do not lose any of their activity by keeping them 

 for three years in the dark. 



Photography itself, as distinguished from its applications, has 

 received considerable attention , and we would point out that if 

 exhibits of this character could be kept together in future exhi- 

 bitions, it would much facilitate their study. A print from the 

 enlargement (four thousand diameters), by Dr. Neuhauss, of a 

 section of a film of a Lippmann interference photograph, copies 

 of which have already been seen here, is exhibited by the doctor 

 himself, and shows very clearly that the silver is deposited in 

 layers, as the theory of the process indicates. Several examples 

 of the Lippmann process may be seen in another part of the 

 exhibition. An interesting demonstration of the possible range 

 of exposure is given by the Kodak Company. They show seven 

 negatives exposed under the same conditions, but for periods of 

 from one to fifty, all of which were developed for the same 

 length of time in the same developer. The longer the exposure 

 the denser the negative, but the prints from them are scarcely 

 distinguishable from one another. They show clearly that a 

 small variation in exposure, or even none at all, will serve for 

 very different subjects if negatives of various densities are not 

 objected to. 



Mr. Thomas Manly, the inventor of the " Ozotype " process 

 of pigment printing, shows some examples of his method, one of 

 which was exposed and washed thirteen months before the pig- 

 ment was applied to it, proving that the power of the exposed 

 bichromated paper to render gelatine insoluble and so fix the 

 pigment does not sensibly change by keeping it. The process 

 which in this country has hitherto been associated with Prof. 

 Joly's name is illustrated by the Colour-photo Company of 

 Chicago, and called the " McDonough-Joly process," referring 

 to Mr. McDonough, who worked out the method in America 

 simultaneously with Dr. Joly. They show that there is still 

 room for improvement in the ruling of the triple coloured lines, 

 and also in the nearer approximation of the photographic plate 

 and the coloured screen. By looking at various angles across 

 the ruling, the colour of the different parts of many of the 

 pictures alternate between green, red and blue. This, we take 

 it, is due to the distance between the colour screen and the photo- 

 graphic plate. Mr. Sanger Shepherd shows some striking 

 examples of his triple film three-colour photographs. 



The most notable novelty in apparatus is the " panoram 

 kodak," for which the Kodak Company have been awarded a 

 medal. All forms of projection have their advantages and their 

 disadvantages. By adopting the cylindric or panoramic per- 

 spective, many subjects are possible for photography that could 

 not be rendered by the plane perspective given by the ordinary 

 fixed lens and plate. The arrangements necessary for a rotating 



