264 



NATURE 



\_7uly 4, 1878 



M. J, S. POLIAKOW, of the Russian Geographical Society, is 

 about to commence his researches in the government of Vladi- 

 mir and in Lithuania into the remains of the stone period. This 

 expedition is in continuation of the labours of M. Poliakow, 

 commenced more than ten years agoi by the discovery of imple- 

 ments of stone in the plane of the river Irkout (1867). Later, 

 in 1871, he found implements of the same kind in the govern- 

 ment of Olonets, on the banks of Lakes Lago, Kenozero, &c. ; 

 in 1874 he found them also on the banks of the lakes of the 

 upper basin of the Volga ; and lastly, the journey which he 

 undertook in 1876, in the valley of the Obi, convinced 

 him not only of the existence of remains of the stone 

 period in Western Siberia, but led him to seek the explana- 

 tion of many stone implements among the implements of 

 peoples possessing only a low degree of culture, as among the 

 Ostiaks. This series of journeys has enabled M. Poliakow to 

 form a very considerable collection of implements in stone and 

 of curious data on the natural history of that epoch. Now, new 

 discoveries have been made by other travellers in the districts of 

 Moiu-om, Vladimir, and in Esthonia, on the banks of Lake 

 Bourtnek, where a tumulus has been discovered containing re- 

 mains of objects connected with cookery. All these discoveries 

 have led M. Paliakow to request the Society to send him into 

 the government of Vladimir and into Esthonia, to study upon 

 the spot these new remains. What attracts the attention of M. 

 Poliakow is that there are, among other things, proofs that, 

 during the stone period, there existed in the small fresh-water 

 lakes a species of seal recalling, by its dimensions and charac- 

 teristics, the seal of Greenland and the Caspian. Another remark- 

 able fact is the discovery made, alongwith the instruments of stone 

 in the district of Mourom, remains of the mammoth. After having 

 investigated the materials referred to, M. Poliakow proposes to 

 visit Stockholm, Copenhagen, and other cities, to inspect the 

 pre-historic museums, with a view to complete the materials he 

 possesses for studying the stone period. 



Dr. Schomburgk, in his Report on the Botanic Garden 

 and Government Plantations of South Australia for 1877, gives 

 an account of an interesting experiment he made with some 

 Arctic wheat. He received a sample of wheat taken from a 

 quantity left by the American Arctic Expedition ship Polaris 

 in 187 1, which had been abandoned in north latitude 81° 16'. 

 This wheat had been left on the beach exposed to the snow and 

 a temperature of 72° to 104° of frost for five years, and was 

 found in a heap by Dr. Ninnis, of H.M. ship Discovery, on the 

 return of the last Arctic Expedition to England. Dr. Schom- 

 burgk received i,CKX) grains, of which he sowed about 300. From 

 the 300 grains about sixty germinated. The plants grew healthy 

 and reached to the height of from three to four feet. It is a 

 bearded wheat, and ripened in the commencement of January. 

 The ears contained about thirty grains each, which were but 

 small, though round and plump. The birds unfortunately 

 destroyed the greater part before it came to maturity, but the 

 interesting fact proves the assertion that the grain of the cereals 

 possesses a vitality not surpassed by any other seed. 



The additions to the Zoological Society's Gardens during 

 the past week include a Japanese Wolf (Cams hodophylax) from 

 Japan, presented by Mr. H. Hey wood Jones ; a Rhesus Monkey 

 (Macacus ErythrcBus^ from India, presented by Mrs. Walcot ; a 

 Brown Capuchin {Cebus fatuellus), a Crested Curassow (Crax 

 elector) from Venezuela, presented by Mr. A. Warmington ; a 

 Mona Monkey {Cercopithecus mono) from West Africa, pre- 

 sented by Capt. C. F. Filliter; a Green Monkey {Ceixopithecus 

 callitrichus) from West Africa, presented by Mrs. George 

 Yeomens ; a Common Marmoset (Hapak Jacchus) from South 

 East Brazil, a Pinche Monkey {Midas cedipus) from New 

 Granada, presented by Mr. Edward Clayton ; a Bonnet Monkey 



{Macacus radiatus) from India, presented by Mr. Allen Forbes ; 

 a Short-Tailed Capromy {Capromys brachyurus) from Jamaica 

 presented by the Hon. J. Burford Hancock ; a Pine Marte, 

 {Maries ahielum) from Ireland, presented by Mr. Robert Walter; 

 six Goldfinches {Carduelis elegans) British Isles, a Common 

 Chameleon {Chamceleon vulgaris^ from North Africa, presented 

 by Mr. C. F. Johnson ; four Cunningham's Skinks {Egernia 

 curminghamii) from Australia, presented by Mr. D. C. Pearson ; 

 a Garden's Night Heron {Nycticorax gardent), a Common Boa 

 {Boa conslrictor) from South America, purchased ; a Green- 

 necked Peafowl {Pavo spicifer) bred in the Gardens. 



A NEW GALVANOMETER FOR LECTURE 

 PURPOSES 



A' 



LL who have had the experience of attempting to exhibit to 

 a large audience the simple phenomena of dynamical elec- 

 tricity will bear testimony to the difficulty of rendering apparent 

 over the whole of a lecture-theatre the movements of a galva- 

 nometer needle. When the galvanometer lies flat upon the 

 table and the movements of the needle itself, or of the index 

 attached to it are observed, the number of observers must be 

 confined to those near at hand. Even the mirror galvanometer, 

 indispensable as it is for delicate experiments, is open to the 

 objection that a popular audience does not immediately appre- 

 ciate the significance of the motions of the wandering spot of 

 light. The devices for projecting the moving needle upon the 

 screen have, up to the present time, been so large and incon- 

 venient as to militate against their use for popular demonstration. 

 These facts led the writer some months ago to attempt to con- 

 struct an instrument for projection upon the screen that should 

 be within the size of an ordinary magic-lantern slide. The early 

 attempts to do this were unpromising, and possessed little 

 sensitivity even for considerable currents. In the latest form of 

 the instrument, however, this defect has been overcome, and the 

 galvanometer has in several trials before large popular audiences, 

 as well as in the teaching of the lecture-room, shown itself to 



answer with complete satisfaction the purposes for which it was 

 designed. 



In the most improved foi;m, the galvanometer consists of a 

 mahogany block the size and thickness of an ordinary magic 

 lantern slider, which serves as a frame to contain the working 

 parts. The coil of wire is wound upon a flat bobbin of brass or 

 ivory, its ends being brought to a pair of terminals at the extremity 

 of the slider. Within the coil the magnetised needle is suspended 

 delicately by a horizontal axis between two adjustable screws. 

 Attached at right angles to the needle is a light index of thin 

 brass or of aluminium. The scale, which is transparent, is 

 reduced by photography upon a glass plate. The arrangements 

 are therefore on a small scale like those of a Becquerel's vertical 

 galvanometer inverted. When no current passes, the index arm 

 hangs downward, the centre of gravity being adjusted very little 

 below the centre of suspension so as to secure the greater degree 

 of sensitivity. But to correct for the dip when the plane of the 

 instrument is nearly in the meridian a small compensating magnet 

 may be placed upon the table below. Thus the slightest move- 

 ment of the needle is at once made visible by the motion of the 

 magnified image of the scale and index; and will be quite apparent 

 even without lowering the lights of the room. 



As the instrument may be constructed with either a short-coil 

 or a long-coil, it can be applied.to a variety of experimental uses. 

 And its portability and simplicity exceed those of any galvano- 

 meter hitherto employed for purposes of demonstration. 



SiLVANUs P. Thompson 



