July i, 1897] 



NA TURE 



205 



{Proposed to present Mr. Millar with a testimonial in recog- 

 nition of his services, and towards this purpose 40/. has been 

 already received. The Rev. Robert Harley, F. R. S., of 

 *' Rosslyn," Westbourne Road, Forest Hill, S.E., has kindly 

 undertaken to receive contributions, which it is hoped will 

 be '■'numerous rather than large,'" the object being to show 

 Mr. Millar how widely his work has been appreciated. 



It is somewhat remarkable that, although the conception of 

 the centre of gravity was evidently known to Archimedes, those 

 of his writings which have been handed down to us nowhere 

 contain either a definition or a proof of the existence of that 

 point. This gap has been attributed to his having treated the 

 subject in a lost work on balances, quoted by Pappus. . An im- 

 portant contribution to our historical information has now been 

 made by Dr. Giovanni Vailati {Atti della R. Accademia delle 

 Scienze di Torino, xxxii.), who has found fresh material in an 

 Arabic translation of an unknown work by Hero, of Alex- 

 andria, in the library of Leyden. This work was brought over in 

 the seventeenth century by Golius, then Professor of Mathematics 

 and of Oriental Languages in the University of Leyden, and 

 attention has recently been directed to it by Carra de Vaux. In 

 it Hero makes numerous references to Archimedes' lost manu- 

 script, from which Dr. Vailati has been enabled to build up, 

 with a fair degree of certainty, the arguments by which 

 Archimedes proved the existence of the centre of gravity. 



Dr. F. Campanile and Dr. E. Stromei {Rendiconti 

 delV Accadeviia delle Scienze di Napoli, iii. 4) describe some 

 further experiments on the phenomena of phosphorescence 

 observed by them in Crookes and Geissler tubes. This phe- 

 nomenon consists in the production of phosphorescence and 

 Rcintgen rays on the walls of a (Teissier tube opposite two 

 plates of tinfoil which were attached to a Ruhmkorff coil or to 

 an electrostatic machine, connected with a spinterometer.— A 

 somewhat different line of investigation has been taken up by 

 Prof. Battelli {Nuovo Ciinento, v., March 1897), who has studied 

 the variations' in the photographic action both inside and outside 

 a vacuum tube, and their dependency on the form and dimen- 

 sions of the tube, the form of the electrodes, the intensity of 

 the current, and the degree of rarefaction. — In a subsequent 

 number of the Nuovo Ciinento, Signor P. G. Melani dis- 

 cusses the influence of magnetism on discharges in vacuum 

 tubes, and describes a number of experiments carried out in 

 Prof. Battelli's laboratory at Pisa. 



Along with a fine series of reptiles lately presented to the 

 Zoological Society's collections, Mr. F. W. Urich has sent from 

 Trinidad a nest of the "Sauba" or Parasol Ant, (Ecodoma 

 cephaloies, the extraordinary habits of which are well known to 

 naturalists. The colony has been placed in a glass case in the 

 Zoological Society's Insect House, where the workers may be 

 seen every day cutting out bits of leaves from a plant that has 

 been provided for their use, and conveying them into their sub. 

 terranean dwellings. 



A NEW Tortoise House, placed near the Reptile House, has 

 just been completed in the Zoological Society's Gardens, and 

 the various specimens of the Testudinata will shortly be removed 

 there from their present quarters on the further side of the canal, 

 so that the whole of the reptile collection will be together. The 

 most remarkable of the tortoises are two fine adult specimens of 

 the Giant Tortoise of the Aldabra Islands in the Indian Ocean, 

 which were presented to the Society by Rear-Admiral Kennedy 

 in 1894. There are also three other examples of the same, or 

 of a nearly-allied species, which have been recently received 

 "on deposit " from the Hon. Walter Rothschild. 



Authorities on Indian birds seem to be unanimous in the 

 opinion that the common little Cotton-Teal or Goose-Teal, 

 Nettopm: coromaudelianus, is unable to stand and walk like 



NO. 1444. VOL. 56] 



other ducks, but invariably flutters along in a strange scuflling 

 manner, like a wounded bird. At a recent meeting of the 

 Asiatic Society of Bengal, Mr. F. Finn gave reasons for doubt- 

 ing the accuracy of this statement. He has had many oppor- 

 tunities of observing Cotton-Teal in confinement, and after 

 watching the gait and movements of numerous specimens, he 

 asserts that the inability to walk, attributed to the species by 

 many observers, is not in reality natural to it, but merely the 

 result of fright, weakness, or injury. 



Science Gossip for June reproduces from the Journal of 

 Malacology some very interesting sciagraphs of shells by Mr. 

 W. M. Webb, which seem to show that the Rontgen rays are of 

 practical value for studying their interior structure. In a paper 

 read before the Natural History Society of Buda-Pesth, Dr. J. 

 Istvanffy states that, in the case of living plants, the Rontgen 

 rays penetrate only the woody tissue. In a leaf of Camellia 

 exposed to them, the veins appeared white. All other tissues, 

 whether containing chlorophyll or not, are impenetrable to 

 them. 



We are glad to see that the Gleaner, of Kingston, Jamaica, 

 is urging the appointment of a geologist to examine the new 

 sections which will be exposed during the construction of a 

 new road now being made over the mountains. The palaeont- 

 ology of Jamaica has been very little studied. There is a very 

 poor collection of fossils in the local museum. It is a little 

 better with mineralogy, but so slight has besn the interest taken 

 in all branches of geological science that there are both fossils 

 and minerals from local sources in the museum, about which 

 there is absolutely nothing known ; all trace of their origin and 

 other circumstances having been lost. What is really wanted 

 is a Government geologist, to devote himself exclusively to 

 geological observations ; and if the appointment of such an 

 officer cannot be entertained at present, the least that should 

 be done is to commission a geologist to map the sections which 

 the road-builders will expose, and save whatever vestiges of 

 vanished ages may be obtained. The facts thus accumulated 

 would be of the greatest value when a survey of the country 

 comes to be made. 



Messrs. Ginn and Co. will shortly publish the first number 

 of the Zoological Bulletin, a companion serial to the Journal of 

 Morphology, and designed for shorter contributions in animal 

 morphology and general biology. The Bulletin will differ from 

 its German prototypes chiefly in excluding, at least for the 

 present, bibliographical lists. Its contents will consist wholly 

 of scientific communications. The editorial work will be directed 

 by Profs. C. O. Whitman and W. M. Wheeler. 



In connection with the excursion of the Geologists' Association 

 to Edinburgh, from Monday, July 26, to Saturday, July 31, the 

 four following papers will be read at a meeting of the Association 

 at University College, London, to-morrow, July 2, at 8 o'clock : 

 — " Outline of the Geological History of the Rocks around 

 Edinburgh," by Mr. J. G. Goodchild ; " Excursions from 

 Bathgate to Linlithgow, and from St. Monans to Elie," by Prof. 

 JamesGeikie, F.R.S. ; " Fish Remains in the Abden Bone-bed," 

 by Dr. R. H. Traquair, F.R.S. ; "The Stirling District," by 

 Mr. H. W. Monckton. 



The Report of the Government Observatory, Colaba, Bombay, 

 for the year ended March 31 last, presents two special points 

 of interest : (i) The introduction of a Dines' pressure tube 

 anemometer, the vane of which is erected about 3 feet 

 above the cups of the Robinson anemometer, and about 6 feet 

 from it. A comparison of the results of the two instruments 

 during the short period of the erection of the new anemometer 

 shows that the average velocity recorded by the old instrument 

 is 42 per cent, more than the average velocity given by the 



