I 28 



KNOWLEDGE & SCIENTIFIC NEWS. 



[June, 1904. 



photographs. The photographs are taken with olijectives of a 

 focal length below that of the range of distinct vision, which in 

 normal sighted people is about ten-and-aquarter inches. 

 Such a photograph viewed in the ordinary way wonid appear 

 to 1)0 out of perspective and its parts out of proportion, thougli 

 .some of this impression could l)e to some extent removed or 

 remedied by magnifying the photograph. 



The accomp.inying figure indicates a method Ii\- which the 



Single l-ens Stereoscope, with Photograph.*;. 



ej'e can obtain a virtual distance-image magnified of the 

 photographs. The apparatus will, in the case of normal 

 vision, bring the different parts of the photograph under the 

 same visual angles as those obtaining at the moment of photo- 

 graphic exposure. ,\n achromatic magnifying lens is u.sed, 

 the focal distance of which is similar to that of the objective 

 used in photographing the object, and which is free from dis- 

 tortion for objects situated at i ,', inches from the nearest lens 



Fig. 3 (Single Lens Stereoscopy). 



surface. The lens (fig. /,) is fiee roni astigmation but not from 

 curvature of field. Therefore when using it the accommoda- 

 tion of the eye nnist be altiirc^d accoi'ding as the central part 

 or the m.irginal part of the photogr;i])hic print isunderinspec- 

 tion ; and the nature of the eye accouunodadon will v.iry for 

 short-sighted, long-sighted, and old-sighted people. Hut if all 

 the directions arc carefully followed, an eye ot normal vision 

 will j)erceive through tlu'lens, not the photograph as it appears 



to the unaided eye, but a far distant im.ige of it, free from dis- 

 tortion, and under the same conditions of apparent size, dis- 

 tinctness, perspective, light and sh.ide as those under wliich 

 the objects themselves would be .seen with the short photo- 

 graphic objective that has been mentioned. Consei|uently 

 the small photograph thus conveys to the eye a much more 

 natural effect than a landscape photograph can possibly do; 

 and unconsciously the vision forins in the mind a correct per- 

 ception of relief and dist.mces. Thus although the stereo- 

 scopic effect is not of the s.ime kind as that produced in ordi- 

 nary stereoscopes, the effect of solidity- is strongly evident 

 and perceptible. A.(.i. 



"Osprey" Plvimes, Real 

 and "Artificial." 



By W. P. PvcRArx, A.L.S., F.Z.S,, \c. 



Without doubt the most beautiful of feather orna- 

 ments is that commonly known as the " Osprey " plume. 

 Mow this name came to he used is a mystery, for the 

 feathers in question are not obtained from the ( Isprey, wliich 

 is a bird of prey, but from various species of Herons, those 

 known as " Efjrets " furnishing the most hif^hly prized 

 varieties. It is from the French form of this word l^gret, 

 that the term " aigrettes," often used instead of " O.sprey," 

 is derived. Naturally, the possibilities of these plumes 

 as head-dresses, both for men and women, have been 

 widely appreciated. Only in the Army, however, have 

 they been worn by men in this country, and the practice 

 has now been happily abolished. To induce our country- 

 women to follow this lead, the most strenuous efforts ha\e 

 been made within recent years to spread a knowledge of 

 the consequences which follow from the encouragement 

 of the traffic created by their demands. Though at last 

 there seems some prospect of success attending these 

 efforts, unless progress towards tliis end is more rapid, the 

 extermination of the hapless victims is inevitable. 

 This in itself would be an end much to be deplored, but 

 the nameless suffering and pain, which accompanies this 

 extinction, makes the "passing of the Egret" a pitifully 

 sad story. 



To many women the broad outlines at least of this 

 matter are already well known, and, as a result, numbers 

 have decided to leave such ornaments severely alone. 

 ( )thers, unable to break the spell wielded by these seduc- 

 tive plumes, have compromised, by forswearing what 

 they believe to be real "Ospreys," and wearing, instead, 

 what they fondly imagine to be an artificial product. 



In purchasing " Ospreys," at least in most milliner's 

 shops, whene\er scruples are manifested, the assistant 

 professes to ha\e doubts about the genuineness of tlie 

 plume, retires to the Manager, and returns, assuring the 

 anxious customer that a mistake has been made, that, 

 after all, the plume is artificial. This fact, long known 

 to the authorities at the British Museum, was shame- 

 lessly admitted, only a few days ago, by the Manager of 

 a large shop in London. " But ladies," he remarked, 

 " arc hard to please, . . . Their consciences have to 

 he soothed, and the assistant, rather than lose valuable 

 custom, readily sells the article as artificial ! " 



In the wholesale trade the word artificial appears to 

 ha\ e been used in a technical sense, long before the agita- 

 tion against the wearing of "Ospreys" began. Inferior 

 " ( )sprey " plumes and feathers of birds other than Egrets 

 or their allies, which have been disguised to simulate 

 " Ospreys," ofe known by the wholesale buyers as 

 '' iiiiififKih." 



