fuly 3, 1884] 



NA TURE 



efficient test of its sanitary condition ; and by what means can and L. ru/a) belonging to the rapacious species which live on othe 

 the high death-rate of children be reduced ? insects. 



The Pavlovsk Observatory has been, since 1SS2, in possession 

 of two subterranean lines, each one kilometre long, and situated, 

 one of them in the direction of the magnetic meridian, and the 

 other perpendicular to it ; and Dr. Wild communicates to the St. 

 Petersburg Academy of Sciences (Bulletin, vol. xxix. No. 2) 

 the following interesting results of his observations on terrestrial 

 currents (the method of observation has already been described 

 in the Memoirs of the Academy, vol. xxxi.): — The terrestrial 

 current altogether does not manifest itself as a current which 

 would (low for a time in one direction and then would slowly 

 change it, but in the shape of more or less strong alternate cur- 

 rents, which rapidly change their direction. The east and west 

 force is generally stronger than that of north and south. The 

 ol. nervations on the regulation days do not show any diurnal 

 periodicity, neither in the force of the current nor in the number 

 of oscillations ; but the average of the twenty-four regulation 

 days of the year (September 1882 to September 1883) disclose 

 such a periodicity, however feeble, namely, a maximum between 

 4 and 5 a.m. and a minimum at S p.m. for the meridional line, 

 ,1- also a maximum at S a.m. and a minimum at I p.m. for the 

 other line. As soon as the force of the terrestrial current is on 

 the increase, the magnetical instruments display perturbations 

 which usually increase with the force of the terrestrial currents, 

 without being, however, proportionate to them. If, according 

 to Sir C'r. B. Airy, the north and south current be compared with 

 the variations of declination, and the other current with horizontal 

 intensity, both perturbations are often very equal, but those "1 

 the currents precede those of the terrestrial magnetism by 

 at least five minutes. This retardation may explain the want of 

 proportion between the variations of the current and those 

 of the terrestrial magnetism, which proportion is the more 

 wanting as the variations of the current are frequent and alter- 

 nate. From these alternations Dr. Will concludes that "ter- 

 restrial currents are always the primary cause of magnetic per- 

 turbations, but not of periodical variations of the magnetic 

 elements." 



Some forty years ago Dr. Joule raised the question whether 

 a body that is magnetised undergoes any change in its tempera- 

 lure ; but the question has not yet received a definite solution, 

 the rise of temperature which accompanies magnetisation being 

 ied by some to induction currents, and not directly to mag- 

 netism. While recognising the influence of the former, Mr. 

 Borgman has tried to show that there is also a change of tem- 

 perature due to magnetisation and demagnetisation, and that the 

 amount of heat thus disengaged is proportionate to the squares 

 of the temporary magnetism. M. Bachmetieft", having made, at 

 the University of Zurich, an extensive series of experiments, the 

 first part of which is now published in the Journal of the Russian 

 Chemical Society (vol. xvi. fasc. 3), arrives at the conclusion that 

 magnetism, by itself, produces variations of temperature in mag- 

 netised bodies, and that this "magnetic heat " is equal to the 

 product of the magnetic moment by the magnetising force 

 multiplied by a constant ; it increases also, within a certain 

 limit, with the frequency of the interruptions of the magnetising 

 current, and increases still more when the direction of the current 

 is alternately changed. Its amount is not equal throughout the 

 length of an iron cylinder, reaching its maximum about its 

 middle and decreasing towards its ends. Its cause must be 

 searched for in purely mechanical forces, and it depends upon 

 the speed of rotation of the molecular magnets. 



About the middle of June the inhabitants of Moscow were 

 puzzled to see immense masses of insects, taken at first for 

 locusts, flying east in thick clouds over the city. It appears 

 now that the insects were dragon-flies (Libellula qundrimaculata 



Count Uvaroff continues his archaeological explorations in 

 the Government of Smolensk, and recently he has found very 

 interesting remains of rude pots containing ashes and bones 

 which are supposed to be burial remains of the Krivitchi, who 

 had the custom, according to the Xestorian annals, of thus burying 

 their dead. 



Dr. CHAVANNE, who is travelling on the Congo for the 

 Brussels National Institute of Geography, has established a 

 meteorological observatory at Bo:aa. Mr. Stanley has trans- 

 ferred the site of his station of Vivi to a table-land some 1500 

 metres to the north ; and a railway from the new station to the 

 Congo is in course of construction. A new station, called 

 Sette-Cana, has also been established at the mouth of the small 

 River Sette. Numerous small wooden houses are being made in 

 Belgium to be transported to the new Vivi. A sanatorium has 

 been constructed at Boma. 



A telegram from Krasnovotlsk gives the true history of the 

 Uzboi, the ancient bed of the Amu Daria. For 250 versts, 

 from Sarykamish to Bola Ishem, there is no stream, this locality 

 presenting a series of desiccated marshes and lakes. At Akkal 

 there is no channel. This part of the Uzboi, which evidently 

 formed an estuary of the Caspian and partially fed the Saryka- 

 mish lake, has been silted up from the sea. The project for 

 uniting the Amu Daria with the Caspian requires several hundred 

 versts of canals. 



M. Jaubert has organised in the Great Tower of the Troca- 

 dero Palace a repetition of the experiments tried by Pascal in 

 the Tour Saint Jacques, on the diminution of barometric pressure 

 with increase of altitude. He is also arranging a Foucault pen- 

 dulum which will oscillate in the same condition as in the 

 Pantheon, with a contrivance for making its vibration perpetual. 



• The additions to the Zoological Society's Gardens during the 

 past week include an Indian Wild Dog (Canis primarvus) from 

 India, presented by Mr. T. A. Bulkeley ; a Brush-tailed Kan- 

 garoo (Petrogale penicilla'a S ) from New South Wales, presented 

 by Mr. J. Abrahams ; a White-collared Mangabey (Cercocebas 

 collaris 6 ) from West Africa, presented by Mrs. Du Heaume ; 

 a Black-eared Marmoset (Hapale penicillata ? ) from South-East 

 Brazil, presented by Mrs. C. Spencer Stanhope ; a Guianan 

 Tree Porcupine (Sphingurus iusidiosus), a Rough Fox (Cam's 

 nulls) from British Guiana, presented by Mr. G. H. Ilawtayne, 

 C.M.Z.S. ; a Laughing Kingfisher (Dacelo giganteus) from 

 Australia, presented by Mrs. W. Moir ; two Chaplain Crows 

 (Corzus capellanus) from Persia, presented by Mr. B. T. Ffinch ; 

 a European Pond Tortoise (Emys europcea), two Spotted Sala- 

 manders (SalamanJra maculosa), European, presented by Mr. 

 J. Satcherd ; two Algerian Tropidosaures (Tropidosaura al & ira), 

 three Rapid Spine-foot Lizards (Acanlhodactylus vulgaris) from 

 North Africa, presented by Mr. W. C. Tait, C.M.Z.S. ; an 

 Adorned Ceratophyrs (Ceratophyrs omata) from South America, 

 presented by Capt. Hairby ; an Orange-winged Amazon (Chry- 

 sotis amazonica) from South America, a St. Thomas's Conure 

 (Conurus xantholrmus) from St. Thomas, W.I., a Yellow 

 Conure (Conurus solstitialis) from Guiana, two Passerine Parrots 

 (Psittacula passer iua) from British Guiana, deposited ; a Bengal 

 Vulture (Gyps bengalensis) from India, two Coscoroba Swans 

 (Cygnus co coroba) from Chili, three Turquoisine Parrakeets 

 (Euphcma fulchella) from New South Wales, purchased ; two 

 Black Guillemots (Uria gty/le) from Ireland, received in ex- 

 change; a Hog Deer (Cervus porcinus S ), four Himalayan 

 Monauls (Lophophorus impeyanus), five Chilian Pintails (Da/i'.a 

 spiiticauda), five Summer Ducks (CEx sponsa), bred in the 

 Gardens. 



