;8o 



NATURE 



\Feb. 14, 1889 



variety of small animals. With regard to the geology of the 

 Selkirks, earlier than the Glacial formation, no rocks later than 

 the Palaeozoic seem to be met with in the central range. In the 

 higher ranges, greenish quartzites and micaceous schists are the 

 commonest rocks. The summit of Mount Bonney and the 

 southern and south-western arites of Mount Sir Donald consist of 

 a beautiful white, smooth quartzite, speckled in the former case 

 with deep brown spots, " probably iron or manganese oxides." 

 Associated with these harder rocks are a number of remarkable 

 silky-looking schists (phylites of Prof. Bonney), the result of 

 great squeezing in the movements which upheaved the ranges. 

 Roughly speaking, then, the configuration of this district, with 

 its complexity of valleys, is due to the disintegration and de- 

 nudation of the softer schists and the permanence of the harder 

 quartzites in mountain-ridges. With regard to age, the rocks 

 range from true Archjean to late Palaeozoic, possibly a little later. 

 The presence of very old schists and gneisses would seem, then, 

 to show that though the range called the Rockies, on the 

 Canadian Pacific Railway route, is the water-parting, the 

 Selkirks are geologically the true continuation of the Rocky 

 Mountains of Montana, and the backbone of the continent. 



The Russian Geographical Society has received the following 

 news from Captain Grombchevski, who was sent out to explore 

 the Khanate of Kunjut in the highlands between India and 

 Afghanistan, and for a time was supposed to have been lost. 

 After having left Marghelan in Russian Turkistan, M. Gromb- 

 chevski crossed the highlands of Alai, and, vid the Pamir lakes, 

 Great Kara-kul, and Rang-kul, he reached the sources of the 

 Amu-daria (the Murghab). Thence he proceeded to the 

 Ak-baital River, and on August 16 he crossed the high ridge 

 on the frontier of Afghanistan. On the southern slope of this 

 ridge the Expedition was overtaken by a violent snow-storm, 

 during which M. Grombchevski's Cossacks succeeded in getting 

 hold of two inhabitants of Turm, from whom they learned that 

 the Expedition was surrounded by Afghan troops, who had been 

 sent out to take them prisoners. In consequence, M. Gromb- 

 chevski, notwithstanding the snow-storm which was still raging, 

 crossed the mountains again and returned to the Pamir, whence he 

 immediately went across the Hindu-kush through a mountain 

 pass which leads to Kunjut. The journey was so difficult that 

 the Expedition lost one-half of its horses and part of its luggage. 

 Circumstances did not permit M. Grombchevski to stay at Kunjut. 

 He re-crossed the Hindu-kush, and entered East Turkistan at 

 the sources of the Raskem-daria, one of the affluents of the 

 Yarkand River. He followed its course, hoping to reach 

 Karakorum, but was soon compelled to abandon his scheme, and 

 only explored the nephrite mines on the banks of the river. 

 After having surveyed part of the Raskem and Yarkand Rivers, 

 the Expedition returned to Little Kara-kul Lake on the Pamir, 

 and reached Kashgar on November 13. Three weeks later they 

 were at Osh, bringing in a mass of interesting information and 

 numbers of photographic views of the explored region. 



The last volume of the Izvestia of the Caucasus branch of the 

 Russian Geographical Society contains a variety of interesting 

 short articles and notes. V. Massalsky's sketches of the regions 

 of Kars and Batum are especially valuable to botanists. M. 

 Konshin gives a most interesting geological and geographical 

 sketch of the Transcaspian region ; and two obituary articles 

 (with portraits) devoted to Abich and Von Koschkul contain 

 excellent reviews of their work in the Caucasus. The appendix 

 contains a note on the study of the Caucasian languages, and 

 various papers relating to Persia, Asia Minor, and Afghanistan. 

 The most important of the latter is a report on the work done 

 by the Russian Commissioners of the Afghan Boundary Com- 

 mission, with a map of the region (13 miles to the inch) brought 

 up to date in 1888. A short paper on the economic conditions 

 of the Russian Transcaspian dominions, and a condensed trans- 

 lation from a "Guide to Armenia," by Bishop Srvandziantz, 

 are also worthy of notice. 



ELECTRICAL NOTES. 

 Hallwachs {Ann. IVicd., vol. xxxiv. p. 731, 1888) is continu- 

 ing his researches on the connection between light and electricity. 

 He has found that if the light of an arc lamp falls on clean 

 plates of zinc, brass, and aluminium, they are always charged 

 positively, the zinc to a potential of over I volt, the brass to 

 I volt, and the aluminium to 0-5 volt. The plates become 

 fatigued by constant illumination. 



Sir William Thomson gave the Friday evening lecture on 

 February 8 at the Royal Institution, on " Electrostatic Measure- 

 ment," and described voltmeters and their functions ; but the 

 most interesting part of his discourse was his approving and 

 eulogistic reference to Hertz's work, his own measurement of 

 "z'," which brings it very close to 3 x 10'" centimetres per 

 second, and his long-deferred conversion to Maxwell's electro- 

 magnetic theory of light, which he thought had sprung from 

 Maxwell's inner consciousness. 



HiMSTEDT {^Ann. Wied., vol. xxxv. p. 126), using a condenser, 

 has determined the value of v to be 3*0093 x lo^**. 



Nahrwold {Ann. Wied., vol. xxxv. p. 107) has shown that 

 platinum rendered incandescent in a closed space is electrified 

 negatively, the air being positive, but the same effect is not to 

 be obtained with hydrogen, or any other pure gas. 



Magnetic elements, Pare Saint-Maur, Paris :— 



January i, 1889. 1888. 



Declination 15° 47''4 - 4'*7 



Dip 65° I5'7 - I'-o 



H 0-19508 -h 0-00028 



V 0-42275 -f 0*0003 



T 0-46559 -t- 0*00039 



E. G. Acheson in New York {Electrical World, January 19) 

 has repeated many of Prof. Oliver Lodge's experiments on the 

 " alternative " path in discharging Leyden jars, but has deduced 

 from them different conclusions. He has avoided the errors due 

 to charging which vitiated Prof. Lodge's early experiments. 

 This is done by using one jar instead of two, and separating the 

 charging system entirely from the discharging. He shows that 

 the effects are due entirely to " extra currents " in the alternative 

 wire dependent on the geometrical form of the current, and 

 modified a little by the electro-magnetic inertia of iron. He has 

 photographed the sparks, and obtains clear traces of oscillation 

 when self-induction is present. His results have little or no 

 bearing on the form of lightning protectors. 



Wesendonck {Ann. Wied. vol. xxxv. p. 450) has made the 

 curious observation that if in a long vacuum tube the distance 

 between the electrodes be increased, the resistance is not affected. 

 This does not agree with Varley's conclusions (Proc. R. S. vol. 

 xix. p. 236, 1871), who showed that after the polarization of the 

 electrodes is overcome gases obey Ohm's law. 



Mebius {Beildatter der F/iysik, vol. xii. p. 678, 1888) has 

 tried to verify the statement that an electric current diminishes 

 the coefficient of elasticity of metals, and he has come to the 

 conclusion that it has no action on elasticity. 



(9yV THE INTENSITY OF EARTH(2UAKES, 

 WITH APPROXIMATE CALCULATIONS OF 

 THE ENERGY INVOLVED.^ 



A S an exact science, seismology is in its infancy. Although 

 -^ great progress has been made during the past ten years, 

 and especially in the development of instruments and methods 

 for a more precise study of seismic phenomena, the results thus 

 far have served rather to reveal the complicated nature of the 

 problems involved ; and while encouraging the seismologist to 

 renewed effort, they warn him that his efforts are not to be 

 light. The recent advances of the science have been, and 

 properly, toward the study of the phenomena at hand, the 

 nature and extent of the motion of the earth particle together 

 with the rate at which the disturbance is propagated, in the 

 expectation and hope that in time the location and character of 

 the original cause may be revealed through these. 



In the early growth of an exact science one of the obstacles 

 met with is the absence of an exact nomenclature, and seis- 

 mology furnishes no exception to this rule. Whenever it 

 becomes desirable or necessary to incorporate the meaning of a 

 word in a mathematicil expression, it is imperative that the 

 necessary restrictions be placed upon its use. It has long been 

 customary to speak of the intensity of an earthquake without 

 any special effort to give the word an exact meaning. Generally 

 it is applied to the destructiveness of the disturbance on the 

 earth's surface, and sometimes to the magnitude of the subter- 



' By Prof. T. C. Mendenhall, President of the Rose Polytechnic Insti- 

 tute, Terra Haute, Indiana. (From the Proceedings of the American 

 Association for the Advancement of Science, 1888.) 



