July 8, 1909] 



NATURE 



45 



preliminary account to the botanical section (No. 7) of 

 Travaux de la SocUte imp^riale des Naturalistes de St. 

 Pi'tcrsbourg (vol. xx.wii., part iii.). Three vertical zones 

 of distribution are distinguished. The littoral zone is 

 narrow, as there is no appreciable ebb and flow ; Ralfsia 

 verrucosa, Corallina virgata, Rivularia polyotis, are the 

 chief forms in certain bays, and in others species of Ulva 

 and Enteromorpha are the most general. The second zone 

 comprises depths from two to eight fathoms, where 

 Cystoseira barbata is everywhere the dominant species. 

 A third zone ranges from ten to thirty fathoms ; Folysi- 

 phonia elongata is the chief formation down to twenty- 

 five fathoms, then Zanardiuia collaris is dominant, and 

 lower Antithamnion pjumula. 



A SERIES of short papers by Dr. J. N. Rose relating 

 to .xerophytic plants of the unrelated but morphologically 

 similar families of the Crassulacese and Cactaceae is col- 

 lected in vol. xii., part ix., of Contributions from the 

 United States National Herbarium. A Mexican plant, 

 formerly described from barren specimens as an Echeveria, 

 is made the type of a new genus, Thompsonella. Another 

 plant from Vera Cruz restores the species Echeveria carni- 

 color. Three new species of the same genus are recorded 

 from Guatemala. The re-discovery of the Cuban species 

 of tree cactus, Cercus nudifloriis, is interesting; other new 

 species are an arboreal Pereskia, a remarkably spiny 

 Echinocereus, and a Nopalea. Dr. Rose also describes 

 a leguminous tree resembling a Cercidium, but sufficiently 

 distinct to be placed in a new genus, Conzattia. The 

 photographs illustrating the habit of these plants are 

 admirable. 



The scenery of the Greater Antilles forms the subject 

 of an interesting paper read by Sir H. H. Johnston at the 

 Royal Geographical Society, and published in the June 

 number of the Geographical Journal. The subject provides 

 ample scope for the author's well-known powers of 

 observation and description. Reference is made to the 

 striking character of the royal palms, Oreodoxa regia, in 

 Cuba, an avenue of which " looks like a column of white 

 marble pillars crowned with a gerbe of glossy green 

 fronds." The palmetto, Sabal palmetto, and two other 

 palms with fan-shaped leaves, Thrinax and Coccothrinax, 

 are prominent in the landscape of the plains and foot- 

 hills. Tall cacti contribute largely to the scenery of eastern 

 Cuba, especially on sandy flats. In the island of Haiti 

 the agaves aroused the author's admiration. With regard 

 to Jamaica, the author presents a sketch of the vegetation 

 in January ; he also offers a word of advice in the matter 

 of retaining such natural beauty spots as Fern Gully. 



We have received revised editions of two useful little 

 manuals: — (i) "Observing and Forecasting the Weather," 

 by Mr. D. W. Horner; and (2) " Some Facts about the 

 Weather," by Mr. W. Marriott. The first is intended for 

 those who may wish to obtain some knowledge of the 

 weather without the use of instruments. For such persons 

 the work contains much useful information ; the chapters 

 on clouds and optical phenomena, from which successful 

 forecasts may often be drawn, are especially interesting, 

 as are also the sections on old weather proverbs and the 

 popular fallacy of the moon's influence. The work is 

 accompanied by some good typical illustrations. The 

 second pamphlet gives " some of the results which have 

 been obtained from present-day systematic meteorological 

 observations in the British Isles," and is of special interest 

 to those possessing instruments for an ordinary climato- 

 logical station. It contains useful information referring 

 to each of the meteorological elements, the use of synoptic 

 XO. 2071, VOL. 81] 



charts, and particulars of average and extreme values ; it 

 also deals with special subjects, e.g. electrical phenomena 

 and the investigation of the upper air, and contains many 

 useful illustrations. The work will be acceptable to many 

 who may wish to obtain accurate general weather know- 

 ledge without reference to more pretentious instructions and 

 text-books. 



The Electrical Review for June 18 contains a list of th° 

 electric tramways, railways, and power companies of the 

 United Kingdom. We note that the following towns head 

 the list of those having electric tramways : — Manchester 

 105, Glasgow 95, London 86, Liverpool 59, Bradford 55, 

 and Leeds 54 miles of track. The leading electric railways 

 are : — the Liverpool and Southport with 35, the Newcastle 

 and Tyneside with 30, the Metropolitan with 26, and the 

 Metropolitan District with 24 miles of double track. The 

 greatest power companies are : — the Newcastle-on-Tyne 

 with a station capacity of 47,000 kilowatts, and the 

 Durham Collieries with 11,000 kilowatts. One of the 

 points which a study of the list brings out is the great 

 popularity of electric traction in the northern towns as 

 compared with the indifference in the south. 



By means of quotations from the " Atomistic " of 1862 

 and the " Weltleben " of 1881 of Robert Grassmann, Dr. 

 F. Kuntze shows in the Physikalische Zeitschrift for 

 June 15 that more than forty years ago the brothers 

 Hermann and Robert Grassmann had worked out the 

 details of an electronic theory to which the electronic 

 theories of the present day bear some resemblance. Accord- 

 ing to the Grassmann theory, the smallest ajther particle 

 consists of a pair of entities to which symbols + E and 

 — E are assigned. The pairs repel each other according to 

 the inverse fourth-power law. When glass is rubbed with 

 silk the -l-E is attracted to the glass, the — E to the silk, 

 and the two bodies become electrified. Light is due to 

 the oscillations of the pairs as pairs, electricity to the 

 oscillation of the constituents of each pair. Heat is the 

 oscillation of matter and the aether pair together. Matter 

 in the same way consists of pairs of elements, and chemical 

 combination of two substances is the attraction of the 

 positive matter element by the negative part of the aether 

 pair, and the negative matter element by the positive part 

 of the sether pair. The positive and negative parts of a 

 pair are supposed to keep apart owing to the motion of 

 each round the other, as in a binary star. 



An interesting article on the mechanical testing of cast 

 iron appears in the Bulletin de la Society d' Encouragement 

 pour I Industrie nationale for May. The author, M. Ch. 

 Fremont, deals first with the historical aspect of his sub- 

 ject, giving drawings of early apparatus, and then proceeds 

 to describe special machines of his own with which he has 

 made many tests on small specimens for the determination 

 of the coefficient of elasticity, the elastic limit, and the 

 breaking strength. The results and plotted diagrams are 

 given, and from these the author arrives at the follow- 

 ing conclusions : — the testing under static bending of cast- 

 iron samples of greatly differing strengths shows that the 

 coefficient of elasticity varies considerably, from simple to 

 triple proportion ; the capacity for elastic bending of cast 

 iron is inversely proportional to its strength ; the elastic 

 limit under static bending varies very greatly, being from 

 0-45 to o-8o of the breaking strength. 



Most of the engineering and shipbuilding periodicals for 

 the week ending June 26 contain reference to the new rules 

 which are on the point of being issued by Lloyd's Register 

 of British and Foreign Shipping. The revised rules are 

 framed to include vessels up to about 6S0 feet in length, 



