212 



NA TURE 



[June 29, 1893 



production of immunity or in healing the disease is the time 

 which elapses between the infection and the protective inocula- 

 tion, that the action of the latter is the more rapid and the more 

 successful the sooner it follows upon the former, it is at once 

 apparent where, at any rate, some of the difficulties lie in its 

 successful application to human beings. Whereas the exact 

 moment is known when theexperimental infection in the animal 

 lakes place, in the human subject days or weeks may pass 

 between the infection and the declaration of the disease. 



THE CENTENARY OF GILBERT WHITE. 



''PHE wonted tranquillity of the little Hampshire village of 

 -'■ Selborne was disturbed on Saturday by the invasion of a 

 band of pilgrims who came to look upon the shrine of Gilbert 

 White, and by the sight obtained a renewed love of nature. 

 Drawn by a feeling of regard, members of the Selborne Society, 

 and other disciples of White, congregated from all parts of the 

 country, and paid homage to their master. Never within the 

 memory of the oldest inhabitant had so many people been 

 gathered together at Selborne, and we doubt not that the vil- 

 lagers failed to realise what attraction there could be in a man 

 whose characteristics, according to an old woman who remem- 

 bered him, were that "he would walk aboutthe lanes tap-tapping 

 at the trees, and stooping every now and then to wipe the dust 

 off his shoes." But one thing marred the enjoyment of Satur- 

 day's meeting. A band of gipsies, with a terrible barrel-organ, and 

 all the paraphernalia of a country fair, had installed themselves 

 not a stone's-throw from the house in which Gilbert White 

 lived his peaceful life. And, worst of all, they possessed a 

 steam-syren, the shriek and screech of which penetrated every- 

 where, even to the high Hangers, in which the Selborne 

 naturalist supposed that swallows hibernated. 



The Earl of Selborne presided at luncheon, and, in propos- 

 ing " The Memory of Gilbert White," dwelt upon the sterling 

 qualities of ihe man, and the remarkable character of his books 

 dealing with the natural history and antiquities of Selborne. 

 White's life was devoted to observing and recording natural 

 productions and phenomena. He was gifted with shrewdness 

 of disceinment, and that one essential qualification of a true 

 man of science — the power of faithfully chronicling all and 

 every observation. It was thought by some that the naturalist 

 whose centenary they were commemorating had nothing else to do 

 but wander about, and observe the habits of bird?, beasts, fishes, 

 and insects ; but that was a great mistake. He had to perform 

 "the daily round, the common task " that falls to the lot of all, 

 and diligently did he fulfil his duties. 



Mr. Darwin proposed " Prosperity to the Selborne Society 

 and its branches." In responding, Mr. Otter, one of the 

 founders of the society, dwelt upon the fact that their object 

 was to inculcate and foster a love of nature, and to wage war 

 in defence of her beauties. To them the ruthless field-naturalist 

 and the sporting collector of specimens were enemies. 



Mr. Wakefield followed with a description of the good work 

 done by the Thames Valley branch in preserving "beauty- 

 spots " from jerry-builders and their kindred. 



The Earl of Stamford, in proposing "Prosperity to the 

 Hampshire Field Club," the members of which joined the London 

 parly at Selborne, remarked that he had found reason to believe 

 that one of the figures shown in the quarto edition of White's 

 book is a likeness of the author himself, hence it could no 

 longer be said that no portrait of him was in existence. Mr. 

 R. II. White, however, was of the opinion that the evidence 

 was not of a positive character. 



The question of a memorial to White was touched by the 

 Earl of Selborne, but he thought that the best plan would be 

 to " Look not on the picture, but the book," and leave that to 

 be handed down to the end of time, for nothing more was 

 needel to perpetuate the memory of the man. With this 

 sentiment we by no means agree. A monument is not erected 

 merely to prevent a man's name and deeds from sinking to 

 oblivion. It should show to the people that he was one whom 

 men delight to honour. We are apt to be far too prosaic in 

 these matters, and to consider the raising of images and other 

 memorials as more or less unnecessary conventionalities. This 

 conviction has grown upon us because we have seen statues 

 erected to comparatively obscure individuals time without 



number, while the works of men of science are unrecognised. 

 It does not .'ay much for the naturalists of this country if the 

 centenary of Gilbert White is allowed to pass without some 

 tangible illustration being given of their regard for the father 

 of them all. 



INTERFERENCE BANDS AND 

 APPLICA TIONS> 



THEIR 



T 



HE formation of the interference bands, known as Newton's 

 rings, when two slightly curved glass plates are pressed into 

 contact, was illustrated by an acoustical analogue. A high- 

 pressure flame B (Fig. i) is sensitive to sounds which reach it in 

 the direction EB, but is insensitive to similar sounds which 

 reach it in the nearly perpendicular direction AB. A isa "bird- 

 call," giving a pure sound (inaudible) of wave-length (\) equal 

 to about I cm. ; C and D are reflectors of perforated zinc. If 

 C acts alone, the flame is visibly excited by the waves reflected 

 from it, though by far the greater part of the energy is trans- 

 mitted. If D, held parallel to C, be then brought into action, 

 the result depends upon the interval between the two partial 

 reflectors. The reflected sounds may co-operate, in which ca:;e 

 the flame flares vigorously ; or they may interfere, so that the 

 flame recovers, and behaves as if no sonnd at all were falling 

 upon it. The first effect occurs when the reflectors are close 

 together, or are separated by any multiple of § ^ 2. t.; the 



second when the interval is midway between those of the above- 

 mentioned series, that is, when it coincides with an odd multiple 

 of J sj 2. \. The factor ^ 2 depends upon the obliquity of 

 the reflection. 



The coloured rings, as usually formed between glass plates, 

 lose a good deal of their richness by contamination with white 

 light reflected from the exterior surfaces. The reflection from 

 the hindermost surface is easily got rid of by employing an 

 opaque glass, but the reflection from the first surface is less easy 

 to deal with. One plan, used in the lecture, depends upon the 

 use of slightly wedge-shaped glasses (2') so combined that the 

 exterior surfaces are parallel to one another, but inclined to the 

 interior operative surfaces. In this arrangement the false light 

 is thrown somewhat to one side, and can be stopped by a screen 

 suitably held at the place where the image of the electric arc 

 is formed. ■ 



The formation of colour and the ultimate disappearance of 

 the bands as the interval between the surfaces increases, dependi 

 upon the mixed character of white light. For each colour the 

 bands are upon a scale proportional to the wave-length for that 

 colour. If we wish to observe the bands when the interval is 



1 Abitract of a lecture delivered at the Royal Institution, on Fridaji 

 March 24, 1893, by Lord Rayleigh. 



NO. 1235, VOL. 48] 



