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HARDWICKE'S SCIENCE-GOSSIP. 



attention was drawn to a white object hanging on to 

 one of the bushes which — contrary to general opinion 

 — can be found on these barren rocks. I thought it 

 was a cocoon of some kind, but found it was a hermit- 

 crab, and on looking around I found several more on 

 the bush. They had climbed from I ft. to 3 ft. from 

 the ground, and seemed to be feeding on the leaves 

 or berries ; and so many more were crawling about 

 below, that their shells, knocking against the stones, 

 made a pattering noise like hail. The sea was quite 

 two hundred yards off, and the sand and stones must 

 have made the journey inland a laborious one for the 

 crabs. It was so curious to see these uncouth crea- 

 tures " up a tree," that I wondered if this was a well- 

 known habit of theirs. — S. F. Clark, M.B., Surgeon- 

 Captain, Medical Staff (Aden, Arabia). 



The Vole Plague. — This creature, which is at 

 present devastating whole districts in Scotland, gene- 

 rally described as a "field-mouse," is nearly con- 

 nected with the water-rat, and allied to the beaver. 

 The fact that they are water-loving animals may 

 perhaps suggest some method of destroying them. 

 They always suffer severely during the long-con- 

 tinued droughts, and they delight in ditches. The 

 wet seasons are thought to have had something to do 

 with their enormous increase. It appears inconceivable 

 that their superabundance can be entirely due to the 

 destruction of their natural enemies. It may be 

 stated that the vole, or short-tailed field-mouse, is 

 found in the colder extremes of three northern con- 

 tinents, while the true field-mouse affects the warmer 

 regions. In Greenland there are voles and no true 

 mice ; in the Tropics there are true mice and no 

 voles ; and there are none in South America, South 

 Africa, or Australia. There is no other mammal in 

 Europe, Asia or America so numerous as the vole, 

 and so prone to petty depredations. Its evil doings 

 have been reported to several Governments besides 

 our own, and in Germany, where this rodent had 

 suddenly increased enormously in numbers, it was 

 officially condemned end executed — in one year— to 

 the number of 1,000,000 or 2,000,000. 



Photographing Flying Bullets. — The "Ama- 

 teur Photographer " contains some details of the ex- 

 periments which Mr. G. V. Boys has been making in 

 photographing flying bullets by the aid of an electric 

 spark. These experiments, it will be remembered, 

 were briefly touched upon by Captain Abney in his 

 presidential address at the Camera Club Conference. 

 The spark, it is said, is generated by the discharge of 

 a Leyden jar, there being in the conductor from it 

 two breaks, which together the electric fluid has not 

 pressure sufficient to jump. But when the bullet or 

 flying object makes contact with one, the spark 

 is instantly emitted from the other. As then the 

 duration of this spark may be even less than the one- 

 millionth of a second, it is far and away in excess of 

 the speed of the bullet, which consequently appears 

 to be stationary, and a very precise view is accom- 

 plished by the camera. This view records the form 

 of the bullet, its direction and inclination, the balling 

 up of the air in front of it, the long-drawn-out vacuum, 

 and the various other vortices and contortions of the 

 surrounding atmosphere through which it is passing. 

 Photographs of actual experiments were then enlarged 

 into gigantic pictures on the screen, and made per- 

 fectly clear in all their singular details^to the audience. 

 Some of the most remarkable were those which 

 showed the passage of a bullet through a sheet of 

 plate glass. In one the head of the bullet was seen 

 protruding, carrying what seemed to be a dark cloud 

 of lead vapour, caused by fusion in the impact, and 



another showed the storm of dust from the smashed 

 up glass ; while others gave views of the strains set 

 up in the glass plate around the clean perforation the 

 bullet had made. Clean perforations of this nature 

 have long been known, but the reason is rendered 

 additionally clear in that the speed of the bullet ex- 

 ceeds the speed at which cracks in the glass can 

 progress. The result, consequently, is that the round 

 portion of glass in front of the bullet is locally pounded 

 into powder before the exterior portions have time to 

 start into motion. Some notice was also taken of 

 the effects of the dust and vapour envelopes of the 

 bullet in the transmission of sound, and also how, by 

 a series of differently-inclined diagonal perforations 

 through the bullet, and the capacity of light being 

 seen through them, the effects of rotation might be 

 observed, and details of the differences of spin effected 

 between that given by the barrel and those produced 

 in the rapid passage of the missile through the air. 



Stockport Naturalists at the Isle of Man. 

 — A number of the members of the Stockport Society 

 of Naturalists during Whit week spent an enjoyable 

 time at the Isle of Man. On arriving at Douglas, 

 where they were met by the President, Mr. P. 

 Kendal, they took train to Port Erin, where they 

 took part in the opening of a Biological Institute, a 

 ceremony which was performed by the Lieutenant- 

 Governor of the Island. They took up residence at 

 Port Erin, and Sunday, Monday, and Tuesday were 

 spent in proceeding with their study of geology, etc., 

 in the island. Much interest was centred in the 

 dredging-vessels which were stationed at Port Erin. 



Kingfishers and the Mayfly. — A correspon- 

 dent in the " Field " asks, Do kingfishers hawk flies 

 or butterflies? I picked up the other day, outside 

 my dining-room window — which is a bay, and can be 

 seen through from side to side — a kingfisher quite 

 dead, with a white butterfly also dead close to it. 

 The bird had no wound of any kind, nor was its 

 plumage hurt. It seems to me it must have flown 

 against the plate-glass, and killed itself by concussion. 

 The butterfly had one wing damaged. I am the 

 more sorry, for, beyond losing the beautiful bird, it 

 was one of a pair which had a nest in the bank of a 

 stream near my house, which my son has since dis- 

 covered had been rifled. We had noticed these birds 

 frequently passing by the house in going to and fro 

 from watercourses in my meadows to the main stream. 

 I cannot help also mentioning the most wonderful 

 mayfly appearance I have ever known. It began 

 last Friday afternoon, and continued up to yesterday. 

 I approach my premises by a bridge across the stream 

 called the Bourne or Burn, an affluent of the Wey, 

 and on Sunday and Monday, in its immediate vicinity, 

 the air was positively clouded with these flies. Every 

 small spray of leaves had flies on it ; they lay about 

 on the ground, and over the stream itself there were 

 swarms. Without exaggeration, I may describe them 

 as being in thousands. I never saw such a sight, and 

 I have been a fisherman off and on for fifty years. 

 Alas ! our stream has no trout to partake of this 

 aldermanic banquet. Yesterday I saw several of the 

 flies at least a mile away from the stream, but there 

 was a high wind. 



Strange Site for a Robin's Nest. — The en- 

 closed cutting is from the "Bradford Observer," 

 May 16th. I can vouch for its authenticity, as the 

 Bowling Club is only a few hundred yards from my 

 residence : — A few weeks ago a pair of robins built 

 themselves a nest in the letter-box of the Manningham 

 Bowling Club. The box is in a door leading into the 



