626 



NATURE 



[April 29, 1880 



College) have been appointed Demonstrators in the Cavendish 

 Laboratory of Experimental Physics. 



The University Commissioners have at last put forward a 

 Statute by which students in " Letters" are to have a Doctorate, 

 so that to Divinity, Law, and Medicine, two new faculties are 

 now added, namely, Letters and Science. The University is 

 also to have power to accept as an affiliated college any college 

 in the British dominions, educating principally adult students, 

 and to allow their qualified students three terms of residence 

 towards those required to obtain a Cambridge degree. 



The Woodwardian Professor gives notice that as he is 

 prevented by illness from returning to Cambridge at present, 

 Mr. Roberts, D.Sc. [Lond], will lecture for him during the 

 present term. 



The returns already received for the Technological Examina- 

 tions of the City and Guilds Institute show that over 1, 100 

 candidates will present themselves for examination at eighty 

 centres. This is a very large increase on last year, when only 

 202 were examined. The examinations are to be held on the 

 evening of May 12, concurrently with the examination of the 

 Science and Art Department on that evening. 



SCIENTIFIC SERIALS 



The Quarterly Journal of Microscopical Science, April. — 

 W. T. Thiselton Dyer, M.A., Assistant-Director, Kew, on the 

 coffee-leaf disease of Ceylon (six plate-). — J. I . Siddall, on 

 Shepheardella, an undescribed type of marine rhiz poda (on the 

 plates Shepheardia), with two plates. The nucleu in this form 

 seems to be unlike anything a- yet described among the rhizopods. 

 The author also figures and describes Lieberkuehnia wageneri 

 from Tenby. This rhizopod is only "a native of Berlin" 

 in a very peculiar sense. Claparede's words are, " Mousn'avons 

 rencontre qu'une seule fois ce rhizopode, a Berlin dans une 

 petite bouteillequi renfermait del'eau de provenance inconnue." 

 The present memoir throws no new li^ht on it- probable affinity to 

 Pamphagus mutabilis. — A. Sedgwick, on the dcel >p uent of the 

 kidney in its relation to the wolffian body in the chicU (with two 

 plates). — F. M. Balfour, notes on the development of the 

 Araneina (with three plates). — Dr. L. Waldstein, a contribution 

 to the biology of bacteria.— Prof. Schafer, some teachings of 

 development. — Prof. T. Jeffery Parker, on the histology of 

 Hydra fusca. — Prof. Giard, on the Orthonectida, a new class of 

 the phylum of the worms (with a plate). — Note- and memoranda. 



American Journal of Science, March. — On a chart of the 

 magnetic declination in the United States, constructed by J. E. 

 Ililgard. — The old river-beds of California, by J. Le Conte. — 

 Age of the Green Mountains, by J. D. Dana. — On a new action 

 of .the magnet on electric currents, by E. H. Hall.— Measures 

 of the polar and equatorial diameter of Mars, made at Princeton, 

 New Jersey, U.S., by C. A. Young. — On the use of the sine- 

 formula for the diurnal variation of temperature, by B. A. 

 Gould. — On the chemical composition of the Uianinite from 

 Branchville, Conn., by W. J. Comstock. — On the mean free 

 path of a molecule, by N. D. C. Hodges. — On the western limit- 

 of the Taconic system, by S. W. Ford. — Principal characters of 

 American Jurassic dinosaurs, by O. C. Marsh. Part iii. 



The American Entomologist, No. 3, new series, March, 1880, 

 contains a multitude of useful notes on que-ti n concerning 

 entomology, amongst which may be noticed trappin ■ the Carpet 

 Beetle (Anthrenus scrophularnz). — The Ailamhus silkworm. — 

 Insects injuring the black locu-t. — The insect tnies of our 

 small fruits, by A. S. Fuller. — The relation be ^ • insects and 

 plants, and the consensus in animil and vegeta li . by L. F. 

 Ward.— Birds b. insects, by the late E. Perris, t -d. — Two 



days collecting in the Mammoth Cave, with u utions to a 



study of its fauna, by H. G. Hubbard, the latter especially inter- 

 esting, giving a list of all the animals hitbert 1 f.und in this 

 celebrated cave, highly illustrated by excellent w 10 cuts, with a 

 description of a very curious new form of p • udo-scorpion, 

 described by Dr. Hagen as Chthonius packard>. It will be a 

 great advantage if the editors of this periodic <1 n in future a 

 resume f the contents of each number. We a' equested to 



notice that it is now published by the Hub Pub g Company 



of Neiv York, 323 Pearl Street. 



Journrf of the Franklin Institute, March. The Edison 



metric light (continued), by Mr. Outerbridg I ummittee's 



report on the Goodwin mowing-machine. — Saws (continued), by 

 Dr. Gnmshaw. —Apparatus for illustrating the aberration of 

 light, by Prof. Tobin.— On the acid products of combustion of 

 coal, by M. Vincotte (translation). — Mica, by Mr. Rand. — A 

 new lecture experiment ; the cupelling of gold and silver. 



SOCIETIES AND ACADEMIES 

 London 



Royal Society, April 8.—" On the Sensitive State of Vacuum 

 Discharges. Part II." By William Spottiswoode, D.C.L., 

 LL.D., Pres.R.S., and J. Fletcher Moulton, late Fellow of 

 Christ's College, Cambridge. 



This paper forms a sequel to that published under the same 

 title in the Phil. Trans., 1879. It describes a continua- 

 tion of the research into the nature and laws of \hz disruptive 

 discharge, or electric spark. The methods of the earlier paper 

 have been extended, and others adapted to the new circumstances 

 have been devised, in order to carry the investigation into high 

 vacua. In particular, independent sources of electricity have 

 been used for effecting the discharge, whether in the sensitive or 

 in the non-sensitive state ; and the results have been confirma- 

 tory of the conclusions derived from the more limited means 

 formerly described. Further, the effects of various tubes con- 

 taining discharges in the sensitive state upon a tube containing a 

 discharge in the non sensitive state have been observed and 

 compared ; and the tube so used as a test has been called the 

 standard tube, and the method of its use the standard tube 

 method. By this means, principally, the laws of the discharge 

 in comparatively moderate vacua have been extended to high 

 vacua. 



In the higher vacua, the phenomena of molecular streams, and 

 the phosphorescence consequent on them, that have been studied 

 ana described by Mr. Crookes, present themselves. These 

 derive great importance for the purpo-es of the present paper 

 from the fact that in high vacua the ordinary luminous discharge 

 becomes so feeble in appearance that it is often difficult to 

 observe. Under these circumstances the phosphorescence, which, 

 like the ordinary luminous effects, may exist either in a sensitive 

 or in a non-sensitive state, forms the best index of what is going 

 on within the tube. Much information as to the nature and 

 procedure of the discharge may be derived from the mode of 

 interference of one molecular stream with another, from the 

 direction and character of shadows cast by these streams, and by 

 a form of interference which has here been called that of virtual 

 shadows. 



The conditions of pressure and of electrical violence, under 

 which phosphorescence is produced, have been carefully studied ; 

 and it has been found that, with a suitable adjustment of the 

 discharge, the phenomena are not confined to high vacua, but 

 can be obtained under pressures much exceeding those of ordi- 

 nary vacuum tubes. The phenomena of these molecular streams 

 have also been compared with those exhibited by the projection 

 of finely divided solid conducting matter when heaped Up over 

 the negative terminal, with the view of ascertaining the nature of 

 the phenomenon and its position in the discharge. 



At the close of the paper the authors have discussed some of 

 the general conclusions which they think may be fairly drawn 

 from their pre-ent researches. First, as to the relative order of 

 magnitude of the time-quantities entering into the discharge ; 

 e.g., the times occupied by the discharge of pjsitive or negative 

 electricity, or of molecular streams, in leaving a terminal ; the 

 time occupied by the same elements in passing along the tube, 

 &c. Secondly, as to the durational character of the negative as 

 compared with the positive discharge, which appears to increase 

 with the degree of exhaustion. Thirdly, as to the mode of for- 

 mation of the positive column ; and fourthly, as to the relation 

 of the molecular streams to the discharge proper. 



But for the details of these conclusions the reader must be 

 referred to the paper itself. 



April 15. — "Description of some Remains of the Gigantic 

 Land-lizard (Megataniaprisca, Owen) from Au-tralia. Part II.," 

 by Prof. Owen. C.B., F.R.S.— Referring to a former Part 

 (Phil. Trans. 1858, p. 43), the author gives, in the present, 

 descriptions of subsequently received fossils of Me^alaniaprisca, 

 advancing the knowledge of that species of large extinct lizard. 

 Characters of the dorsal, sacral, and caudal vertebrae, with those 

 of a considerable portion of the skull, are detailed. So much of 

 the upper jaw as is preserved shows the species to have had that 

 part sheathed with horn as in the tortoise. Upon the head were 



