650 



NATURE 



[October 30, 1890 



group, but in the former case the bright carbon flutings are 

 strongly "developed, whilst in the latter they are barely visible. 

 Another characteristic of the later species is the addition 

 of absorption-lines to the narrow bands. The observations of 

 Mr. W. J. Lockyer and myself show that 5 Piscium represents 

 a late stage of the group, there being little or no carbon 

 radiation. 



(4, 5) Stars of the solar type. The usual differential observa- 

 tions are required. 



(6) A star of Group IV. Observations of the relative thick- 

 nesses of the hydrogen and additional lines should be made, and 

 the characters and positions of the latter noted. It appears that 

 in some of these stars the added lines are similar to those seen 

 in a Cygni, whilst others are solar. 



(7) In this star of Group VI. the blue zone is very pale, the 

 carbon band K 564 is very wide and dark, and band 4 is sus- 

 pected (Duner). 



(8) There will be a maximum of this variable on October 31. 

 The period is about 138 days, and the range from 7 '5-8 "5 to 



2'5-i3"o. According to Duner, the spectrum is one of Group 

 I., but excessively weak. More details may possibly be obtained 

 f the spectrum be observed at maximum. A. Fowler, 



Spectroscopic Observations (Sawerthal's Comet 

 1881 I., AND )8 Lyr/E)— Dr. Nicolaus von Konkoly, the Di- 

 re ctor of the Astro-physical Observatory in O'Gyalla (Hungary) 

 has issued the volumes containing his observations made during 

 1888-89. Henotes, with respect to Sawerthal's comet (1881 I.): — 



" I have observed the spectrum with a Merz universal spectro- 

 scope having one prism in position. This gave a dispersion of 

 8° (H to D), which was more than sufficient for my purpose. 

 I was obliged to use this instrument, because the deviation it 

 gave suited the focussing arrangement of the Kartaler refractor. 

 The telescope of the spectroscope magnified seven times. 



" The continuous spectrum was not very bright, and faded 

 away slowly at each end. I thought that I could distinguish 

 the D line (dark). It was so weak, however, that I could not 

 •fix its position with the micrometer. The continuous spectrum 

 extended from 673 (x to 435 yu. Besides this I was able to 

 recognize five hydrocarbon bands which I have located five 

 times. From these measurements I have deduced the follow- 

 ing mean values: I. 56i-46;u, II. 546'25ju, III. 5I5"88 /i, IV. 

 SI3-26m,V. 472-56^. 



"The lines were not sharply defined on either side, and were 

 much widened near the continuous spectrum. The measure- 

 ments given above are of the middle of the maximum light- 

 intensity of the bands, which could be easily distinguished." 



|8 Lyrae was spectroscopically observed on January i, 1889, 

 and it is recorded : — " The C line was bright and could be 

 easily seen, and a dark band was visible at a slight distance from 

 it. D3 was distinguished in a similar manner. Near it, in the 

 green, some fine lines could be perceived. F was suspected, 

 but it vas almost invisible." 



Dr. Konkoly gives an extended account of his observations of 

 Jupiter from 1885 to 1889, and accompanies it with a series of 

 fourteen drawings of the planet. Several drawings of Sawer- 

 thal's comet are also given. 



Spectroscopy at Paris Observatory. — M. Deslandres 

 has charge of the spectroscopic section just created at Paris 

 Observatory, and in the current number of Coinptes rendtis 

 (October 20) he gives an account of the instruments to be used 

 with the great equatorial ( i '20 metres aperture). Those who 

 have tried to obtain photographs of star spectra by means of a 

 slit spectroscope on a large telescope, know how difficult it is to 

 adjust a star on the slit, and, when there, to keep it in position 

 for a sufficiently long time. To enable this to be done during a 

 long exposure, M. Deslandres has arranged a total reflecting 

 prism near the dark slide, so that the red end of the spectrum 

 ■may be seen whilst the blue end is being photographed. In 

 this way he has obtained many photographs of stellar spectra in 

 juxtaposition with comparison spectra. To adjust the instru- 

 ment for observing, the spectrum of a star, a small mirror, 

 having a hole in the centre about the same diameter as the 

 length of the slit, has been fixed in front of the slit at an inclina- 

 tion of 45°. The image of a star is thus reflected to the side of 

 the instrument, and after another reflection reaches a small tele- 

 scope fixed at the spectroscope. This telescope, therefore, 

 gives the image of a star in the plane of the slit, and constitutes 

 a veritable finder for use with the spectroscope. 



NO. 1096, VOL. 42] 



ON THE LATER PHYSIOGRAPHICAL GEi 

 LOGY OF THE ROCKY MOUNTAIN REGION 

 IN CANADA, WITH SPECIAL REFERENCE 

 TO CHANGES IN ELEVATION AND TO THE 

 HISTORY OF THE GLACIAL PERIOD.^ 



Tr\R. G. M. DAWSON has been engaged continuously for 

 ^-^ seventeen years in geological exploration of the Western 

 Territories of Canada, including the country from Lake Superior 

 to the Pacific ; and in the paper above named he summarizes the 

 history of the successive deposits and earth-movemenis which 

 have built up the mountain ranges of the West, and the relations 

 of these to the geology of the great plains to the eastward. He 

 devotes special attention to the Glacial age, and concludes that 

 the drift phenomena of the plains belong to a period of sub- 

 mergence, and that in the exti-eme period of glaciation there 

 were great glaciers on the Cordillera on the west, and the Lau- 

 rentian axis on the east, with a vast internal sea between. He 

 is thrfs entirely opposed, as far as North America is concerned, 

 to the idea of a Polar ice-cap or a great continental glacier 

 flowing down the interior plateau of the continent, and he re- 

 solves the phenomena of the ice age into the operation of huge 

 mountain glaciers and floating ice. 



The leading points of the memoir may be summarized, with 

 the aid of a few extracts, in such a manner as to convey a gene- 

 ral view of the history of the great Cordilleran belt, which 

 stretches along the west coast of America from Behring Straits 

 to Cape Horn, and more especially to indicate that of its more 

 northern portion. 



The general structure of the country may be defined as 

 follows : — 



" At the present day, the western border region of the con- 

 tinent is formed by a series of more or less nearly parallel 

 mountain systems, with an average breadth in British Columbia 

 of about 400 miles. The trend of these systems is north-west 

 and south-east, or similar to that of the corresponding portion 

 of the Pacific shore-line, the position of which, in fact, depends 

 upon that of these orographic features. This generally moun- 

 tainous zone of country is often referred to as the Rocky Moun- 

 tain region, but is more appropriately named the Cordillera 

 belt, the Rocky Mountains proper constituting only its north- 

 eastern marginal range. In traversing it from east to west, in 

 the southern part of the province of British Columbia, four 

 distinct mountain-systems are crossed : (i) the Rocky Mountains 

 proper, (2) mountains which may be classed together as the 

 Gold Ranges, (3) the Coast Ranges, (4) an irregular mountain- 

 system which in its unsubmerged parts constitutes Vancouver 

 Island and the Queen Charlotte Islands, and which may be 

 designated the Vancouver system. Between the second and 

 third of these mountain-systems is a region without important 

 mountain ranges, which is referred to as the Interior Plateau of 

 British Columbia. 



" To simplify our conception of the main features of this part 

 of the Cordillera for our present purpose, we may, however, 

 regard it broadly as being outlined on the north-east and south- 

 west sides by the Rocky Mountains proper and by the Coast 

 Mountains, as dominant ranges. This view is justified by the 

 remarkable constancy of these two ranges and their relative 

 importance. The intervening region may then be descsibed as 

 comprising the Interior Plateau together with the various ranges 

 which have been grouped together under the name of the Gold 

 Ranges, as well as other detached mountains and irregular 

 mountainous tracts." 



The geological history of British Columbia begins, like that 

 of many other parts of the world, with that primitive crumpling 

 of the earth's crust which produced the Laurentian gneisses. 

 These exist principally in' the Gold Ranges, and are in this region 

 neither greatly extended nor of great elevation. In the Palceo- 

 zoic age there were sea-bottoms receiving sediment, but apparently 

 little mountain-making. 



" Omitting, then, from consideration the imperfectly-known 

 progress of events in the earlier stages of the geological history 

 of the region, we may endeavour to picture to ourselves its con- 

 dition in the Triassic or first stage in the Mesozoic division of 

 geological time. The central region of the continent was at 

 this time occupied by a very extensive, though shallow, medi- 

 terranean sea, which was either entirely cut off from the ocean 



" By Dr. G. M. Dawson, F.G.S., Assistant Director of the Geological 

 Survey of Canada. Transactions of the Royal Society of Canada, 1893. 

 73 pages quarto, with 4 maps. 



