November 20, 1902] 



NA 'J URE 



65 



in a recent letter to the Times. He points out that the door on 

 the left of the traveller with his face towards the engine, with its 

 hinge forward, is safe ; but the door on the right, with latch 

 forward, is very unsafe to open even slightly. The wind 

 rushing by at hurricane speed gets into the opening, snatches 

 the door wide open, thereby pulling the unwary passenger with 

 his hand on the latch out on the line. If the door is six feet by 

 three and the wind is exerting an average pressure of twenty 

 pounds to the square foot, the force on the open door is as much 

 as three cwts. 



A recent issue of the Scientific American contains a de- 

 scription of the multiplex system of page-printing telegraphy 

 described by the late Prof. II. A. Rowland. In this system, 

 alternating currents are used for transmitting the signals, which 

 are made up by suppressing different combinations of two half- 

 waves in a series of eleven half-waves. The transmitting instru- 

 ment has a typewriter keyboard, and four operators work over 

 the same line ; the messages sent by the different operators are 

 separated by a commutator, which rotates in a quarter of a 

 second and allows each operator to use the line for one-quarter 

 of this period. In this way, with duplexing, 1920 signals or 

 320 words can be sent over one line in a minute. The receiving 

 instrument prints the message on a sheet of paper, spacing it 

 out into words and lines so that it appears like an ordinary type- 

 written sheet. It is said that the system has been successfully 

 operated under the Government in America over a distance of 

 550 miles. 



The paper on " Electric Tramways" read by Messrs. C. and 

 B. Hopkinson and E. Talbot before the Institution of Civil 

 Engineers last week derives especial interest from the fact that 

 it is based on the experience gained by the authors in the con- 

 struction of the tramways at Leeds and Newcastle-on-Tyne. 

 The chief points considered were the generation and trans- 

 mission of power, the construction of rolling stock, and the 

 vexed question of earth returns and electrolysis. It is interest- 

 ing to note that the authors find that with seventy or more cars 

 the load is so nearly constant that the steam consumption per 

 unit is practically the same as for a constant load. In such a 

 case, therefore, batteries are only needed as a stand-by or for 

 night work. As regards electrolysis, it is stated that experi- 

 ments showed that, except in special circumstances, the 

 7-volt Board of Trade limit might be exceeded many times 

 without risk of damage to gas and water pipes, but if high 

 •conductivity stiata existed at certain parts, there might be con- 

 siderable damage caused by the leakage currents even below 

 the 7-volt limit. 



The Report for the year ended December 31, 1900, of the 

 Meteorological Service of Canada, compiled by the director, 

 Mr. R. F. Slupart, has now reached us. The report consistsof 

 an introduction in which the Canadian observing stations are 

 classified and the weather conditions summarised for each 

 month of 190). This is followed by separate parts, containing 

 monthly and annual summaries for the chief stations ; meteor- 

 ological summaries for telegraph reporting stations ; bi-hourly 

 and hourly temperatures and barometric pressure during 1900 ; 

 mean, maximum and minimum temperatures ; rainfall and 

 snowfall in 1900 ; and amount of bright sunshine registered in 

 each month. 



A striking instance of the value of the work performed by 

 meteorological observatories to those engaged in agriculture is 

 contained in the last report of the chief of the U.S. Weather 

 Bureau. On the morning of February 23, 1901, the following 

 special warning was telegraphed from Washington to Jackson- 

 ville, Florida, with instructions to give it the widest possible 

 distribution throughout the State. " Temperature will fall to- 



NO. I725, VOL. 67] 



night to a minimum of between 20/ and 25 at Jacksonville, and 

 to freezing as far south as Tampa, with frost extending somewhat 

 south of the latitude of Jupiter." Frost occurred as predicted, 

 and the minimum temperature at Tampa was 32 . More than 500 

 telegrams were sent from the Weather Bureau office at Jackson- 

 ville, and the railroads of the State energetically cooperated in 

 disseminating the warnings. Fruit and vegetable growers 

 estimated the value of orange bloom, vegetables and strawberries 

 known to have been saved, as a result of the warnings, at more 

 than a hundred thousand dollars. 



In part iv. of vol. lxxii. of the Zeitsc/11 ift fiir wissenschaftliche 

 Zoologie, Herr K. Hesse brings to a conclusion his valuable 

 account of recent researches on the visual organs of inverte- 

 brates. 



The latest issue of Gegenbaur's Morphologisch.es Jahrbuch 

 (vol. xxx. part iv.) contains a " symposium " on the morphology 

 of the cloaca and certain of the reproductive organs of the 

 amniote vertebrates. 



In the Emu for October, Mr. A. W. Milligan gives an 

 illustration and description of the nesting-mound of one of the 

 megapodes, the mallee (Lifoa ocellata). It appears that in hot 

 weather the birds remove the top of the heap so as to form a 

 saucer-like depression, which is again filled up when the 

 weather becomes rainy. The author was fortunate enough to 

 see the cock-bird performing the latter operation. A feature of 

 this number of the Emu is the beautiful plate of the eggs and 

 nest of the chestnut backed quail. 



The evidence as to the origin of the paired limbs of verte- 

 brates forms the subject of an article by Prof. B. Dean in the 

 October number of the American Naturalist. This evidence, 

 it is urged, is strongly in favour of the view that paired limbs 

 have been developed from skin-folds running along the sides of 

 the body, as exemplified in the earliest and most primitive 

 sharks. In the same issue, Prof. D. S. Jordan discusses the 

 coloration of fishes, and concludes that, as in other vertebrates, 

 some colour-types in this group serve for protection, others act 

 as recognition-marks, while others, again, have been developed 

 for sexual attraction. 



We have received the prospectus, together with an advance 

 copy of the preface, of the long-expected work on the mammals 

 of Egypt commenced by the late Dr. John Anderson and com- 

 pleted by Mr. W. E. de Winton, which promises to be of the 

 highest value to naturalists. For many years before his death, 

 Dr. Anderson had been assiduously collecting Egyptian 

 mammals ; but, even with the assistance of others, the series 

 of specimens available to the authors, although very large, was 

 not in all respects complete. Mrs. Anderson, who made all 

 arrangements for the publication of the work and has super- 

 vised its contents, has herself contributed the preface. The 

 price of the work, which is uniform with Dr. Anderson's 

 " Reptiles of Egypt," has been fixed at seven guineas net. 



The Illustrirte Zeitung of September 18 contains a good 

 figure of the aye-aye of Madagascar, taken from a specimen 

 living in the Zoological Garden of Berlin. It is, however, quite 

 incorrect when Dr. Heck, who writes the accompanying lelter- 

 press, claims that this is the only figure of this animal ever drawn 

 from life. Prof. Owen's celebrated memoir on Chiromys 

 madagascariensis, published in the fifth volume of our Zoological 

 Society's Transactions in 1862, contains an excellent figure of 

 this animal, taken from the specimen living in the Regent's Park 

 Gardens in October, 1862, and drawn by the celebrated artist 

 Joseph Wolf. There have been at various timts/<?«>- examples 

 of the aye-aye living in the Zoological Society's Gardens, and 

 its anatomy and osteology were elaborately desciibed from them 



