December, 1910. 



KNOWLEDGE. 



483 



that no animal shams death so successfully, or keeps it up 

 for a longer time than these small insects. Much of my 

 earlier work had to be repeated owing to my failure to realize 

 this. .Afterwards I started a mortuary incubator, kept at the 

 most favourable conditions of temperature and moisture, and 

 only concluded that my specimen was dead after giving 

 it plenty of time to recover in this elysium." In breeding this 

 species I have frequently removed numbers which I took to 

 be dead, but after keeping them for a short time in a tempera- 

 ture of SO F.. quite 90 per cent. ha\e conmienced to run 

 about again. 



THE ECONOMIC ST.ATUS OF WILD BIRDS.— 

 There has been quite a flood of letters in the press recently, 

 with reference to the vexed question of the economic status 

 of wild birds, and. like previous outbreaks of this character, 

 the main issues have largely been lost sight of. What the 

 majority of farmers and fruit growers, small holders, and so 

 on, contend is that certain birds are practically wholly 

 injurious, eg,, the sparrow, wood pigeon, and bullfinch, and 

 therefore should not be afforded any protection ; whilst others, 

 to a large extent beneficial, have unduly increased in numbers 

 of recent years and now constitute a pest, e.g., the rook, 

 starling, blackbird, thrush, and others, and these also should 

 not receive protection for a time. 



Whatever town-dwellers, bird-lovers, collectors, and so on 

 think to the contrary, in actual farm practice ample evidence is 

 forthcoming in support of these contentions. Further, post 

 mortem examinations of the crops and stomachs show that, 

 although during part of the year some of these birds do destroy 

 a certain number of injurious insects or their larvae, during the 

 greater proportion they feed upon fruit buds, grain and vegetable 

 matter, very much to the farmer's detriment. No one wishes 

 to see our avian fauna ruthlessly destroyed, but to contend 

 that no species are injurious is the best possible way to induce 

 the farmer to indiscriminately kill all he can. A right control 

 is reall>- what is most desirable. . 



ENEMIES OF RATS. — The recent outbreak of plague in 

 Suffolk once again brings into prominence the question of the 

 extermination of the rat. There can be little doubt but that 

 the increase of these pests is due, to a large extent, to the ruth- 

 less destruction of their natural enemies. The kestrel, owl, 

 stoat and weasel annually destroy a considerable number of 

 rats, but. owing to the prejudice that exists with reference to 

 them amongst gamekeepers, they are killed in large numbers. 

 It is very difficult to convince these gentlemen that owls are 

 practically harmless to game, and that the rat does far more 

 harm than kestrels, stoats and weasels. In France and 

 Germany these natural enemies are much more highly valued, 

 and consequentlv protected, much to the advantage of the 

 agriculturalist and game preserver. The publicity which at 

 present is being given to the damage caused by the rat and the 

 danger it is as a carrier of plague-infected fleas, will no doubt 

 cause the thoughtless to consider whether it would not be 

 better to encourage its natural enemies as the lesser of the two 



HOUSE FLIES AND THE PUBLIC HEALTH.— A 

 large number of readers of '" Knowledge " have written me 

 with reference to this most important matter, one that 

 concerns the economic biologist, the medical profession, 

 departments of Public Health, and the public generally. I 

 cannot now deal with the various suggestions and queries 

 beyond stating that I welcome them and fully appreciate their 

 importance, and will endeavour to deal with some of them 

 next month. There is just one point upon which I should 

 like to say a few words, and that is that the statement that 

 flies " as carriers of the germs of such diseases as typhoid 

 fever, tuberculosis, infantile diarrhoea, and so forth, are a 

 potential danger " is not lacking scientific corroboration. 

 There is an abundance of evidence, some of which I 

 will deal with later, to prove this beyond all doubt, and I 

 must confess some surprise that anyone should have doubts 

 about it. 



GEOLOGY. 



By Ru.ssei.l F. Gwinnell, B.Sc, A.R.C.S., F.G.S. 



GEOLOGY FOR THE LAYMAN.- Every November 

 a series of lectures, free to the public, is delivered under the 

 auspices of the British Museum (Natural History! by a 

 graduate in medicine of a Scottish University. These 

 " Su-incy Lectures on Geology" were this year given bv 

 Dr. T. J. Jehu. M.A., F.R.S.E.. who dealt with " The Coasts 

 of Great Britain and Ireland." Among the matters dealt 

 with in the twelve lectures were raised beaches and submerged 

 forests, waves and winds, erosion and accretion, sands and 

 sand-dunes, and the fauna and flora of the coast-line. The 

 lectures were well illustrated by lantern slides. 



Considerable attention appears to have been devoted to 

 geological subjects in the new (11th) edition of the Encyclo- 

 paedia Britannica, the publication of which is announced by 

 the University of Cambridge. Including Mineralogy and 

 Petrology the geological articles number nearly one thousand, 

 while the main article. " Geology," contributed by Sir 

 Archibald Geikie, alone runs to fifty thousand words, Mr. 

 H. B. Woodward is responsible for the general arrangement 

 of the articles, and Messrs. F. W. Rudler and L. J. Spencer, 

 and Dr. J. S. Flett, are associated with the mineralogical and 

 petrological branches. 



THE MAKING AND READING OF MAPS.— Three 

 lectures delivered under the auspices of the Royal Geographi- 

 cal Society by its map-curator, Mr. E. .A. Reeves, F.R.A.S.. 

 F.R.G.S.. appear in book-form under the title " Maps and 

 Map-making " vpublished by the Royal Geographical Society, 

 1910). The history and development of surveying instruments 

 is dealt with, followed by a summary of the principles and 

 methods of geographical surveying, and a description of the 

 operations and processes of map-construction. 



Almost simultaneously there has appeared " -A study in the 

 Geography of the Surrey Hills," by Miss Ellen Smith, under 

 the somewhat clumsv title, " The Reigate Sheet of the One 

 Inch Ordnance Survey " (A. and C. Black. 1910). This 

 little book may be regarded as an instalment of the scheme 

 proposed by Dr. H. R. Mill for the regional description of the 

 United Kingdom, and initiated by his own description of the 

 .Arundel Sheet. Miss Smith deals first with the geology of 

 this " Surrey highland " district, and afterwards with topo- 

 graphy, vegetation, economic resources and industries. The 

 study of communications, place-names and the position of 

 farms and towns completes an interesting volume. A series of 

 folding maps issued with the book includes two on geology. 

 One hopes to see volumes on a similar plan dealing with other 

 areas which are of special interest. 



A large relief-map or model of the Ingleborough district, 

 which was recently constructed by Mr. J. F. Stockhouse, 

 F.R.G.S.. and published uncoloured, has been taken in hand by 

 the Geological Survey of England and Wales. The outcome is 

 the production of a geologically coloured edition and a 

 descriptive memoir. This memoir, like a previous one 

 on the model of the Isle of Purbeck, is written by Mr. Aubrey 

 Strahan, M.,A., F.R.S. Such models, with accompanying 

 memoirs, are likely to be very useful in the teaching of geology 

 in its relation to geography. 



J.AP.ANESE GEOLOGY. — .Among the " natural resources " 

 of Japan, illustrated at the recent Japan-British Exhibition at 

 Shepherd's Bush, few branches were better dealt with than 

 those of Geology and Mining. The Geologists' .Association (of 

 London) visited these collections shortly before the close of 

 the Exhibition. 



.As a supplement to these exhibits, the Japanese Government 

 publication, ■'.'\7i;n'H^ in Japan. Past and Present" (1909) is 

 useful. We learn that the history of the exploitation of 

 mineral wealth goes back into the remote past. Pre-historic 

 ornaments of micaceous iron ore and psilomelane may not 

 indicate any knowledge of metallurgical processes, but actual 

 records of the manufacture of swords and metallic mirrors date 

 from 660 B.C. Eight hundred years later, an annual tribute of 



