33<^ 



NATURE 



\Feb. 6, 1879 



Second, its mountains trend east and west, from the Pyrenees 

 to the Carpathians and the Caucasus beyond, near its southern 

 border ; and they had glaciers of their own, which must have 

 begun their operations, and poured down the northward flanks, 

 while the plains were still covered with forest on the retreat from 

 the cTeat ice-wave coming from the north. Attacked both on 

 front and rear, much of the forest must have perished then and 

 there. Third, across the line of retreat of those which may 

 have flanked the mountain-ranges, or were stationed south of 

 them, stretched the Mediterranean, an impassable barrier. Some 

 hardy trees may have eked out their existence on the northern 

 shore of the Mediterranean and the Atlantic coast. But we 

 doubt not, taxodium and sequoias, magnolias and liquidam- 

 bars, and even hickories and the like were among the missing. 

 Escape by the east, and rehabilitation from that quarter until a 

 very late period, was apparently prevented by the prolongation 

 of the Mediterranean to the Caspian, and thence to the Siberian 

 ocean," 



Prof, Gray shows that on the American continent on the other 

 hand the trees, when touched in the north by the incoming 

 refrigeration, had only to move their southern border southward, 

 along an open way, as far as the exigency required ; and there 

 was no impediment to their due return. The still greater rich- 

 ness of north-east Asia in arboreal vegetation may find an 

 explanation in the prevalence of particularly favourable con- 

 ditions, both anteglacial and recent, 



" The case of the Pacific forest is remarkable and paradoxical. 

 It is, as we know, the sole refuge of the most characteristic and 

 wide-spread type of miocene coniferse, the sequoias ; it is rich 

 in coniferous types beyond any country except Japan ; in its 

 gold-bearing gravels are indications that it possessed, seem- 

 ingly down to the very beginning of the glacial period, magno- 

 lias and beeches, a true chestnut, liquidambar, elms, and other 

 trees now wholly wanting to that side of the continent, though 

 common both to Japan and to Atlantic North America, Any 

 attempted explanation of this extreme paucity of the usually 

 major constituents of forest, along with a great development of 

 the minor, or coniferous, element, would take us quite too far, 

 and would bring us to mere conjectures." 



Prof. Gray concludes his interesting lecture by saying : — 

 " I have done all that I could hope to do in one lecture if I 

 have distinctly shown that the races of trees, like the races of 

 men, have come down to us through a prehistoric (or pre- 

 natural-historic) period ; and that the explanation of the present 

 condition is to be sought in the past, and traced in vestiges, and 

 remains, and survivals ; that for the vegetable kingdom also 

 there is a veritable archaeology." 



UNIVERSITY AND EDUCATIONAL 

 INTELLIGENCE 



The Cambridge Smith's Prizes have been awarded to Micaiah 

 John MuUer Hill, B.A., St. Peter's College, and Arnold Joseph 

 Wallis, B.A., Trinity College, bracketed equal. These gentle- 

 men were also bracketed equal as fourth wranglers in 1879. 



A University for ladies will be opened shortly in Odessa. 

 It will have three faculties — History and Literature, Mathe- 

 matics, and Natural Science. The programme will be the same 

 as in the other Russian Universities for male students, with a 

 few changes. Greek will not be obligatory in the Historico- 

 Literary Faculty ; there will be in the same faculty a Chair of 

 Political Economy and Statistics. Pedagogy and hygiene will 

 be obligatory in all faculties. 



SCIENTIFIC SERIALS 



Annalen der Physik und Chemie, No. 12, 1878. — In an in- 

 augural dissertation here given, Herr Nahrwold studies atmo- 

 spheric electricity ; his method of experiment having been to 

 electrify air in a cylindrical vessel fitted with a (mercury) dropping 

 collector. His first attempts, with points, convinced him that only 

 the dust, not the air, could be thus electrified ; he then successfully 

 used a fine platinum wire kept glowing with a battery (the air 

 having been first freed from dust), and a condenser or galvanic 

 element connected with the circuit. Interesting data are furnished 

 with regard to the charge of the air, the ratio of this to the 

 source of electricity used, and the decrease of the charge. Some 

 ot the observations seem to throw doubt on Thomson's conclusions 

 as to the distribution of electricity in the upper regions of the 



atmosphere. — Herr Wiedemann offers a theory on the nature of 

 spectra, deduced from the kinetic theory of gases. Line-spectra 

 are attributed to oscillatory motions of atoms, isolated at high 

 temperatures ; band spectra of elements and spectra of compounds 

 to vibrations of atoms in the molecule, or of the ether-envelopes. 

 — A quantitative verification of the electrodynamic law, regard- 

 ing the reciprocal action of closed circuits, for the case in which 

 the circuit suffers deformation, is furnished by Herr Niemoller. — 

 Herr Korteweg discusses the velocity of propagation of sound in 

 elastic tubes, and Herr Riihlmann gives formulas for measure- 

 ment of ocean depths with the manometer. —There are several 

 notes on crystallography. 



SOCIETIES AND ACADEMIES 

 London 



Royal Society, January 23. — " Researches on Lactin," by 

 Edmund J. Mills, D.Sc, F.R.S., "Young" Professor of Tech- 

 nical Chemistry in Anderson's College, Glasgow, and James 

 Hogarth. 



The authors have investigated lactin with the aid of polarised 

 light, their object being to gain further insight into the chemical 

 nature of that compound. Their conclusions are as follows : — 



1. The initial specific rotation of lactin is <)2°'6t,. 



2. The permanent specific rotation of lactin is 59°' 17- 



3. The change of rotation of a solution of lactin can be ex- 

 pressed by a mathematical equation. 



4. When the specific rotation 64'''8 is reached, the law of 

 change must be expressed by a different equation. 



5. The initial solubility of lactin is one part lactin in 10*64 

 parts water, 



6. The permanent solubility is one part lactin in 3*23 parts 

 water. 



" Researches 'on Chemical Equivalence," Part II, Hydric 

 Chloride and Sulphate. By Edmund J. Mills, D.Sc, F,R,S., 

 and James Hogarth, 



While carrying out their researches on lactin, it struck the 

 authors that use might be made of it to compare the dynamical 

 equivalents of acid bodies. They accordingly selected hydric 

 chloride and hydric sulphate for the measurements in question. 



The results show that though 2HCI may be the "equivalent" 

 of H2SO4 in weight for saturation (i.e., in the ordinary sense), 

 it certainly is not the equivalent in the dynamical sense. They 

 also render it highly probable that HCl is equal dynamically to 

 H2SO4, Ostwald, by a method based on the alteration of 

 the specific volume of solutions, has shown that the ratio 



^ = I'g-?, a result which their numbers, though not as 



HsS04 ^^ 



perfect as the authors could wish, nevertheless strongly confirm, 



" Limestone as an Index of Geological Time," by T. Mellard 

 Reade, C.E. 



January 30. — " On Certain Means of Measuring and Regu- 

 lating Electric Currents." By C. William Siemens, D.C.L., 

 F.R.S. 



The dynamo-electro machine furnishes us with a means of pro- 

 ducing electric currents of great magnitude, and it has become a 

 matter of importance to measure and regulate the proportionate 

 amount of current that shall be permitted to flow through any 

 branch circuit, especially in such applications as the distribution 

 of light and mechanical force. 



On June 19 last, upon the occasion of the soirh of the Presi- 

 dent of the Royal Society, was exhibited a first conception of an 

 arrangement for regulating such currents, which the author has 

 since worked out into a practical form. At the same time a 

 method has been realised by which currents passing through 

 a circuit, or branch circuit, are measiured, and graphically 

 recorded. 



It is well known that when an electric current passes through 

 a conductor heat is generated, which, according to Joule, is pro- 

 portionate in amount to the resistance of the conductor, and to 

 the square of the current which passes through it in a unit of 

 time, and advantage has been taken of this well-established law 

 of electro-dynamics, in order to limit and determine the amount 

 of current passing through a circuit. 



The paper refers to three instruments, in the first of which 

 one end of a thin strip of metal is attached to a screw, by which 

 its tension can be regulated ; it then passes upwards over an 

 elevated insulated pulley, and down again to the end of a short 



