■ifte 24, 1875] 



NATURE 



157 



es a belief in the homological identity of organisation 

 veen very distant groups of the animal kingdom, a belief 



,.„;oh all recent embryological research has only tended to 



confirm. 



{To be continued.) 



SCIENTIFIC SERIALS 



American Journal of Science and Arts, June. — The original 

 articles in this number are : — Results of dredging expeditions of 

 the New England Coast in 1874, by A, E. Verrill. More 

 than 100 species new to the launa of southern New Eng- 

 land were secured. Most of these are northern species, 

 but many are undescribed. A table giving nature of bottom 

 and temperature at the surface and bottom of the sea is 

 given. — Mr. Fontaine's paper on the Primordial Strata of Vir- 

 ginia is continued and concluded. At the end is given a 

 comparison with the metamorphic crystalline rocks of the Blue 

 Ridge. — On the occurrence of the Brown Hematite deposits of 

 the Great Valley, by Frederick Prime, jun. — Note on some new 

 points in the elementary stratification of the Primordial and 

 Canadian rock of south central Wisconsin, by Roland Irving. 

 The order for the Lower Silurian strata of Wisconsin has been 

 generally accepted as (beginning from below) i. Potsdam sand- 

 stone ; 2. Lower magnesian limestone ; 3. The St. Peter's sand- 

 stone ; 4. The blue and buff limestones ; 5. The Galena lime- 

 stone ; 6. The Cincinnati group. The succession as now made 

 out is (beginning from below) i. The Lower or Potsdam sand- 

 stone ; 2. The Mendota limestone ; 3. The Madison sandstone ; 



4. The main body of limestone ; 5. The St. Peter's sandstone. 

 A table of correlation is given with the Mississippi Bluffs and 

 the Minnesota River. — On the application of the horizontal pen- 

 dulum to the measurement of minute changes in the dimensions 

 of solid bodies, by Prof. O. N. Rood. — On diabantite (a chlorite), 

 by G. W. Hawes. — Re-discovery of double star H.I. 41, by 



5. W. Burnham. It is about 46' north of the well-known double 

 star »|/' Draconis, and is easily found without an equatorial 

 mounting. — On the distnbution of electrical discharges from 

 circular discs, by C. J. Bell. — Examination of gases from the 

 meteorite of Feb. 12, 1875, by A. \V. Wright.— On limonite 

 with the colour and transparency of golhite, by Prof. Mallet. — 

 Under the head "Scientific Intelligence," the original notes 

 are : — On the surface geology of Ohio ; On the Prototaxites of 

 Dawson ; On the Crustaceans of the caves of Kentucky and 

 Indiana, together with several reviews. 



Fourth and Fifth Annual Reports of the Wellington College 

 Natural History Society, Dec. 1872 to Dec. 1874. — We are 

 gratified to see that this Society is in a much more hopeful con- 

 dition than it was when we noticed its last Report, the tone of 

 which was almost despairing. The attendance has been very 

 much better, and the interest taken in the Society by the boys is 

 evidently increasing. Judging from the lists a fair amount of 

 field-work in natural history has been done, and the Society is 

 gradually forming good collections. But, as the preface to one 

 of the Reports hints, there is still much room for improvement in 

 the subjects and character of the papers read at the meetings. 

 Except in the case of lectures by outsiders, the majority of the 

 papers are the result of reading and not of observation or experi- 

 ment, and not many of them can strictly be called scientific. 

 Now, however useful such exercises as these may be to the boys, 

 this is scarcely the sort of work one looks for from members of a 

 Natural History Society, We think this Society might well take 

 a leaf out of the Rugby Society's Report, and go in much more 

 extensively for organised field-work, encouraging the boys to use 

 their eyes and their hands on nature as well as on books, and to 

 bring forward papers embodying the results of their observations, 

 papers of a character similar to the interesting one of the presi- 

 dent, the Rev. C. W. Penny, on " Natural History in the 

 Christmas Holidays." Not only would the members thus reap 

 much benefit, both in the way of discipline and instruction, but 

 M'e are sure a greater interest in the Society would be created in 

 the School. The Society has evidently got a good second start, 

 and we trust that the next Report will show as great an advance 

 on the two under notice as these do on the previous one. 



Riga Society of Naturalists.— Hos. 8 and 9 of this Society's 

 publications contain three papers of importance, besides meteoro- 

 logical reports and notes of smaller interest. The more im- 

 portant papers are : On some theories of earthquakes, by Prof. 



Schweder.— On the changes in the Dlina estuary, by M. Gott- 

 fried. — On the fauna of Spitzbergen, by Prof. Nordenskjbld, 

 showing that this fauna consists of 15 species of quadrupeds, 23 

 of birds, 23 of fishes, 64 of insects, 100 of CrustaceJE, and 130 

 of sea molhiscs. — There is also an obituary notice of the late 

 Dr. Ernst Nauck, who died at Riga on Jan. 26 last. 



SOCIETIES AND ACADEMIES 



London 



Royal Society, June 10.— "Experiments on Stratification 

 in Electrical Discharges through Rarefied Gases," by William 

 Spottiswoode, M.A., Treas. R.S. 



In the stratified discharges through rarefied gases produced by 

 an induction-coil working with an ordinary contact-breaker, the 

 striae are often unsteady in position, and apparently irregular in 

 their distribution. Observations made with a revolving mirror, 

 which the author hopes to describe on another occasion, have 

 led him to conclude that an irregular distribution of strise does 

 not properly appertain to stratification, but that its appearance is 

 due to certain peculiarities in the current, largely dependent 

 upon instrumental causes. 



The beautiful and steady effects obtained by Mr. Gassiot with 

 his Leclanche battery, and also more recently by Mr. De la Rue 

 with his chloride-of-silver battery, have abundantly shown the 

 possibility of stratification free from the defects above men- 

 tioned ; but it must be admitted that the means employed by 

 those gentlemen are almost gigantic. The present experiments 

 were undertaken by the author with the view of ascertaining, 

 first, how far it was possible to approach towards similar results 

 with instruments already at his command ; and secondly, whether 

 these would afford other modes of attack, beside the battery, on 

 the great problem of stratified discharges. 



The induction-coil used was an "18-inch" by Apps, worked 

 occasionally by six large chlcride-of-silver cells, kindly lent the 

 the author by Mr. De la Rue, but more usually by ten or by twenty 

 Leclanche cells of the smallest size ordinarily made by the Silver- 

 town Company. He has also, in connection with the same coil, 

 120 of the latter cells, connected in twenties for quantity, and 

 forming six cells of twenty times the surface of the former. These 

 work the coil with the ordinary contact-breaker very well, giving 

 ii-inch sparks whenever required. A "switch" affords the 

 means of throwing any of the three batteries in circuit at 

 pleasure. 



Having reason to think that the defects in question were 

 mainly due to irregularity in the ordinary contact-breaker, he 

 constructed one with a steel rod as vibrator, having a small 

 independent electromagnet for maintaining its action. The 

 details of construction of this contact-breaker are described. 



With a contact-breaker of this kind in good action, several 

 phenomena were noticeable ; but first and foremost was the fact 

 that in a large number of tubes (especially hydrocarbons), the 

 striae, instead of being sharp and flaky in form, irregular in dis- 

 tribution and fluttering position, were soft and rounded in out- 

 line, equidistant in their intervals, steady in proportion to the 

 regularity of the contact-breaker. These results are, the author 

 thinks, attributable more to the regularity than to the rapidity of 

 the vibrations. And this view is supported by the fact that, 

 although the contact-breaker may change its note (as occasionally 

 happens), and in so doing may cause a temporary disturbance in 

 the stratification, yet the new note may produce as steady a set of 

 striae as the first. And not only so, but frequently there is heard, 

 simultaneously with a pure note from the vibrator, a strident 

 sound, indicating that contacts of two separate periods are being 

 made, and yet, when the strident sound is regular, the stria: are 

 steady. On the other hand, to any sudden alteration in the 

 action of the break (generally implied by an alteration in the 

 sound) there always corresponds an alteration in the striae. 



The author then attempts to show the extreme dehcacy in 

 action of this kind of contact-breaker, or "high break," as it 

 may be called. 



The discharges described above are usually (although not 

 always) those produced by breaking contact ; but it often 

 happens, and that most frequently when the strident noise is 

 heard, that the current produced by making contact is strong 

 enough to cause a visible discharge. This happens with the 

 ordinary as with the high break ; but in the latter case the double 

 current presents the very remarkable peculiarity, that the striae of 

 one current are so arranged as to fit exactly into the intervals of 



