June 8, 1893] 



NATURE 



the narrow tube, and the position of the thread of mercury 

 •s then read off on a scale. In one of the instruments con- 

 structed, which has a reservoir of 5 cc. capacity, a change of 

 level of I mm. at 20 atmospheres corresponds to a change 

 of pressure amounting to I in 2500, so that it may safely be 

 said that at 50 atmospheres the same change of level indicates 

 a change in pressure of one-fiftieth of an atmosphere. But 

 this amount of sensitiveness may be increased by making the 

 reservoir longer, and since it is possible to take readings to 

 O'l mm., the instrument may be said to indicate differences as 

 small as l in 25,000. The variation in height of the mercury 

 must of course be allowed for, and the tube and reservoir 

 accurately gauged before the instrument is set up. After use at 

 a high pressure it can be opened to the air, when the compressed 

 gas will escape in bubbles through the wide tube. It is found 

 that the instrument is easily made strong enough to work with 

 safety at 100 atmospheres. 



A REPORT on "The Hawks and Owls of the United States,'' 

 with special reference to the economic status of the various 

 species, has been prepared by Dr. A. K. Fisher for the U.S. 

 Department of Agriculture. Of the seventy-three species and 

 sub-species described only six prove to be injurious, and three 

 of those are extremely rare. The contents of about 2700 

 stomachs of hawks and owls were examined, and omitting the 

 six species that feed largely on poultry and game, 56 per cent, 

 contained mice and other small mammals, 27 per cent, insects, 

 and only 3 J per cent, poultry or game birds. This result shows 

 that a class of birds commonly looked upon as enemies to the 

 farmer really rank among his best friends. The report contains 

 twenty-five colouredjplates. 



At a meeting of the Norfolk and Norwich Naturalists' Soci- 

 ety, held on May 30, a resolution with regard to the Wild Birds 

 Protection Bill now before the House of Lords was unanim- 

 ously passed, and the president requested to forward the same to 

 the Earl of Kimberley, one of the Vice-presidents, asking his 

 cooperation with its objects. The result of the proposed amend- 

 ments would be that the County Council should be empowered 

 to order the protection of certain specified districts easily 

 defined, rather than the eggs of specified species, which, in 

 many instances, so closely resemble those of other species (as 

 for instance, those of Ihe Teal and Gargany Teal, and the 

 Ruff and_ Redshank) that their identification would be so difficult 

 to establish as to render a conviction practically impossible. 



In the fourth annual report of the Missouri Botanical 

 Garden, which has just been published, Mr. W. Trelease gives 

 the results of further studies of yuccas and their pollination. 

 Mr. Albert S. Hitchcock also contributes a description of plants 

 collected in the Bahamas, Jamaica, and Grand Cayman. 



Messrs. Blackie and Son have added another to their already 

 large number of science text-books. " Chemistry'for All," by W. 

 Jerome Harrison and R. J. Bailey, is a tersely-written account 

 of the chemistry of common things, in which equations, 

 formula;, chemical symbols, and arithmetical calculations are 

 eschewed. There is little new in the book, either in the 

 text or illustrations. 



Messrs. Macmillak and Co. have just published a fine 

 work by Mr. G. W. Caldwell Hutchinson, entitled "Some 

 Hints on Learning to Draw." A few excellent, though brief, 

 remarks on elementary anatomy precede the description of 

 drawing the human figure, but artists do not yet seem to realise 

 the equal importance of knowing something about the elements 

 of physical science before conceiving pictures of natural 

 phenomena. 



Messrs. Gauthier-Villars have issued two small volumes 

 by M. p. Minel on "L'Electricitt- Industrielle." One deals 

 NO. 1232, VOL. 48] 



with potential lines of force and electro-magnetic units, and in 

 the other, magnetic circuits and induction machines are con- 

 sidered. The object of the author has been to bring together 

 the theoretical principles necessary to the proper understanding 

 of dynamo-electric machinery and electric lighting. 



A USEFUL little book by M. Henri Coupin on " L' Aquarium 

 d'Eau Douce " has recently been published by Messrs. Bailliere. 

 It is well illustrated, and should be interesting to young natural- 

 ists. The author describes how to capture, preserve, and study 

 some of the common types of plants and animals found in fresh 

 water. 



A translation of Dr. Migula's " Introduction to Practical 

 Bacteriology," by M. and H. J. Campbell, has just been pub- 

 lished by Messrs. Swan Sonnenschein and Co. The German ^ * 

 edition was reviewed in these columns on June 30, 1892. 



The Geological and Natural History'Survey of Minnesota 

 have issued their twentieth annual report. Among other papers 

 contained in the report is one by Mr. N. H. Winchell on " The 

 Crystalline Rocks, some preliminary considerations as to their 

 Structure and Origin," and Dr. A. C. Lawson gives the results 

 of a survey of the raised beaches of the north shore of Lake 

 Superior. 



A USEFUL syllabus of an elementary course of botany has 

 been received from the author, J. Bentley Philip. It is pub- 

 lished by James G. Bisset, of Aberdeen. 



Prof. IIerdman writes to us : — " During the Whitsuntide 

 vacation the Liverpool Marine Biology Committee spent two days 

 in dredging from Port Erin, and the rest of the time in work on 

 the shore and in the Biological station. On one day the 

 weather was sufficiently fine to allow of the steamer working 

 on the seventy fathom depression which lies to the west of the 

 Isle of Man, half way to the Irish coast. The bottom there is 

 a fine stiff grey-blue mud or clay, which, it has been suggested, 

 may be of glacial origin. We searched very carefully through 

 dredgefuls of this unpleasantly tenaceous cold mud in the hope 

 of finding some stones or shells which might settle the matter, 

 but in vain. The animals on this ground include the Crustaceans 

 Calocaris macandrewea and Pasiphaa sivado, a Polynoid {Pan- 

 thalis oerstedi) in enormous muddy tubes and Lipobranchius 

 jeffreyiii, Echinoderms ^»;//;z'ar« c/iiajiiaxii Brissopsis lyrijera 

 (in quantity), Virgularia mirahilis, and the Molluscs Isocardia cor 

 and Rissoa abyssicola. On a previous trip, shortly before this, 

 one of our party obtained fifteen living specimens of Isocardia 

 cor on this ground. The rest of the dredging on the two days 

 was carried on nearer Port Erin, along the west side of the 

 Isle of Man, at depths of twelve to forty-six fathoms. Among 

 the more noteworthy forms obtained were the Echinoderms 

 Thyone raphanus and EchinocardUim Jlavescens, a calcareous 

 sponge Ule glabra (found before at Guernsey), the Ascidians 

 Eugyra glutinans, Polycarpa comata, and a considerable number 

 of the rare Forbesella tessellata (which present such variations 

 in shape, general appearance, colour and texture, along with 

 identity in anatomical characters, as to enable me to say that 

 Forbes's Cynthia tessellata and C. limaci}ia are undoubtedly one 

 and the same species), and the moUusca Oscanius membran- 

 aceus, Coryphella landsburgi, and Cyclostrema millepunctatum, 

 Friele, which is new to British seas. One of our reporters 

 on Mollusca (Dr. Chaster) tells me that Canon Norman, who 

 has seen our specimens of the Cyclostrema, and compared them 

 with one of Herr Friele's type specimens in his collection, writes 

 that the species has only been taken by the Norwegian North- 

 Atlantic Expedition at Stat. 192 (Lat. 69°46' N., Long. 16° 15'E.), 

 off the northern part of Norway, at a depth of 649 fathoms. 

 Anomalocera patter sonii was very conspicuous in the surface 

 nettings, and additional specimens of the new l.ichomolgus (L. 



