May 3, 1877] 



NATURE 



19 



more like that produced by a coil will be exhibited. The latter 

 form of discharge appears to the unassisted eve as an unbroken 

 column of light, but with a negative glow and dark space. A 

 revolving mirror, however, resolves the column into a regular 

 array of stricc, having a rapid proper motion towards the positive 

 terminal. 



With a view to examining the transition from the stratified 

 to the unstratified form as closely as possible, a Iloltz machine 

 was employed, wiih a battery of one or more jars. The outside 

 of this battery and ore terminal of the tube were connected with 

 the earth ; and the inside and the other terminal were alter- 

 nately connected with the positive conductor of the machine, so 

 that the battery was alternately charged and discharged through 

 the tube. The amount of charge was regulated partly by the 

 distance through which the conductors of the machine weie 

 separated, and partly by the number of revolutions of the machine 

 during which the charging took place. 



The first object proposed was to ascertain whether a jar could 

 be charged with so small a quantity of electricity as of itself to 

 give a stratified discharge in a tube. 



A number of tubes tried with various amounts of battery 

 charge, but with the same surface, showed that, as the charge 

 was increased, the head of the positive column advanced towards 

 the negative terminal, the dark sp.ace became narrower, and the 

 glow contracted in dimensions ; and when the head of the 

 column drew very near to tlie negative terminal, the glow, 

 instead of covering the whole surface of the terminal, formed a 

 .small drop at the point. On still further increasing the charge, 

 the drop withdrew to the hilt of the terminal ; and finally, when 

 it had completely retreated into the hill, the continuous or true 

 jar-discharge took place. 



With a view to testing experimentally how far the effects here 

 described were due to quantity, and how far to tension, the size 

 of the jar was altered, all other circumstances remaining the same. 

 It was then found that the maximum charge compatible with 

 stratification ^^•as greater -h ith a large than with a small jar. 



As a further experiment in this direction, a series of jars were 

 arranged in cascade, and it was found that the greater the number 

 of jars so arranged the smaller the charge necessary to ensure a 

 true jar-discharge. A charge insufficient to destroy stratificaticn 

 with onejar was sufficient to destroy them when more than onewas 

 used in cascade. These results point to tension rather than to 

 qu.intity as the determining cause of the character of the 

 discharge. 



The duration of the stratified discharges observed throughout 

 these experiments was exceedingly short, indistinguishable, in 

 fact, from that of the true jar-discharge. When viewed in a 

 revolving mirror they showed no srgn whatever of prolonged 

 duration, ar,d we may thence conclude that, so far as our present 

 instrumental arrangements extend, there is no inferior limit to 

 the duration of discharge necessary for the prcduclion of strice. 



A conif arisen of the results here obtained with those detailed 

 in Part ii. of these researches, shows that the phenomena pro- 

 duced by suitable disposition ol the Leyden battery coincide with 

 those produced by the induction-coil. With the coil it was 

 found that (i) for a given electromotive lorce the column of 

 strias was shorter the larger the battery surface or strength of 

 current used ; (2) that the prober motion, when directed as 

 usual towards the positive terminal, was n ore rapid the greater 

 the electromotive force employed. With the LeyfJen battery it 

 was found that (i) in order to maintain the same length of 

 column with an increased surface the charge must be increased 

 in a larger proportion than the surface ; and (2) it was noticed 

 that the striK which when the tensif n Avas low were distinct and 

 well separated, became mere blurred as the tension rose, until 

 they sometimes were blended into an apparently unbroken 

 column of light. The presence, however, ol the negative glow 

 still showed that the true jar-discharge had not yet been reached. 



Geological Society, April 11. — Prof. P. Maitin Duncan, 

 F.R.S., piesident, in the chair. — John Robert Campbell, James 

 Carter, Wrlliam Radcliffe Ellis, William Hamilton Merritt, 

 William Morgans, and Edmund Albert Parsick, were elected 

 fellows of the societ)'. The following communications were 

 read : — On sardworn stones from New Zealand, by John D. 

 Enys, I'^.G.S. The author exhibited sjiecimens of sandworn 

 pebbles from near Wellington, in New Zealard, and described 

 their mode of occurrence. — The Bone- caves of Cresswell Crags, 

 third paper, by the Rev. J. Magens Mello, F.G.S. In this 

 paper the author gave an account of the continued exploration of 

 these caves, and of the completion of the examination of the 



Robin Hood Cave, noticed in his previous communications. 

 Five deposits could be distinguished in the Robin Flood Cave, 

 namely, when all present : — I. Stalagmite, 2 feet. 2. Breccia, 

 with bones and flint implements, i foot 6 inches. 3. Cave- 

 earth, with bones and implements, i foot 9 inches. 4. Mottled 

 bed, with bones and implements, 2 feet. 5. Red sand, with b^nes 

 and quartzite implements, 3 feet. The most important discoveries 

 were made in the cave-earth, and chief among these was a frag- 

 merit of bone, having on it a well-executed outline of the head 

 and neck of a horse, the first recnrded discovery of any such 

 work of art in this country. As the result of the exploration of 

 these caverns, the author said it is evident that during the 

 Pleistocene period, Derbyshire and the adjoining counties were 

 inhabited by a very numerous and diver^sified fauna, the vast 

 forests and pastures which extended far to the east and south offer- 

 ing a congenial home to the mammoth, the woolly rhinoceros, the 

 hippopot.imus, the Irish elk, the reindeer, the bison, and the horse, 

 whilst among them the h)rena, the glutton, the be.nr, the lion, 

 the wolf, the fox, and the great sabre-toothed ]\lachairodus, 

 roained in search of prey ; and that with these and other 

 animals man lived and waged a more or less precarious struggle, 

 amidst the vicissitudes of a varying climate, sheltering himself in 

 the numerous caves of the district, which were already the 

 haunts of the hya;naand its com.panions. — On the mammal-fauna 

 of the Caves of Creswell Crags, by Prof. W. Boyd Dawkins, 

 F.K. S. In this paper the author gave anaccount of the remains 

 found in the caves explored by the Rev. J. M. Mello. He 

 stated that the recent explorations had proved that the Robin 

 Hood Cave was inhabited by hya'nas, not only during the depo- 

 sition of the cave-earth and breccia, but also during th.at of the 

 red-sand clay underlying it, which had .also furnished traces of 

 the existence of man. After noticing the conditions of the fossil 

 bones found in the caves, the author proceeded to remark upon 

 the general results of the explorations with regard to their 

 Pleistocene fauna, and concluded that there is no evidence from 

 these or other caves in this country to prove that their faunas .are 

 either pre- or inter-glacial, and that we have no proof of the 

 existence of pre- or inter-glacial man in Britain. 



Zoological Society, April 17. — Mr. Osbert .Salvin, F.R.S., 

 in the chair. — The secretary exhibited and made remarks on 

 some young Anacondas which had been produced dead by the 

 larfje female Anaconda purchased on February 15. — The .secre- 

 tary exhibited some photographs of the young gorilla, now living 

 in the Berlin Aquarium, and made sc-me remarks on what, it 

 now seemed certain, was an example of this ape, which was 

 formerly living in one of Wombwell's travelling menageries, and 

 was after its death transferred to the late Mr. C. Waterton's col- 

 lection. — A letter was read from Mr. W. A. Willes, in which he 

 gave an account of the success whicli had attended the endeavours 

 of the Acclimatisation Society at Christchurch to introduce 

 salmon into New Zealand from the Uni'ed States. — A com- 

 munication was read from' Mr. W. A. Forbes, F.Z.S., con- 

 taining a description of the peculiar organ knov.-n as the Bursa 

 /"«/';;«>■ in birds, and of its variations and modifications in the 

 different genera of the class which he had had an opportunity of 

 examining. — A communicaticn was read from M. L. 'I'ac- 

 zanowski, in which he gave a list of the birds collected in North- 

 western Peru in 1876 by Messrs. Jelski and Holzmann. 

 Amongst several new and interesting forms described was a new- 

 genus and species of Fringiilidae proposed to be called Gimtho- 

 spiza raimondii. — A communication was read from the Rev. R. 

 Boog Watson, containing some notes on the Madeiran Mollusc 

 identified by the Rev. R. T. Lowe as Achalina Jolliculus. — A 

 communication was read from Mr. E. P. Ramsay containing the 

 concluding portion of his list of birds met with in Norlh- 

 Eastern Queensland, chiefly at Rockingham Bay. — A communi- 

 cation was read from Dr. Otto Finsch, containing a preliminary 

 account of the birds collected during his recent journey in the 

 North-Eastern part of Turkestan — A communication was read 

 from Prof. Owen, containing the description of a new species of 

 extinct kangaroo of the genus Sthcviiius, which he proposed to 

 call Sth. minor, together with some remarks on the relation of 

 this genus to Dorcofiis. — Mr. Edgar A. Smith read a paper con- 

 taining descriptions ol new species of South-American Hdicida 

 in the British Museum. — The Marquis of ;Tweedda]e, F.R.S., 

 gave descriptions of four new species of birds from the Indian 

 region. These he proposed to name as follows : — Tric/wstoma 

 Uiuoprocta, Chyysococfyx livibori^i, and Fomatorhiuns nusfaii 

 (from Tenasscrim), and Brackypteryx /iKxloiii (hoxn .Sumatra). — 

 Mr. Oslert Salvin exhibited and pointed out the character of a 



