4IO 



NATURE 



[July 13, 1916 



OVR ASTRONOMICAL COLUMN. 



A Partial Eclipse of the Moon. — ^The moon will 

 be in partial eclipse during the early morning hours 

 of Saturday, July 15. The first contact with the 

 shadow occurs at 3h. igsm. a.m., the angle from the 

 north point being 40° to E. At Greenwich the moon 

 sets at 3h. 59m. a.m. (one hour later in legal time), 

 nearly 47 minutes before the middle phase. 



A Bright Meteor. — A notable meteor was observed 

 at the Hill Observatory, Sidmouth, early on July 8. 

 First seen at ih. 5m. a.m. G.M.T. a little E. of N. 

 about 15° above the sky-line, rising in the sky, it then 

 passed not quite overhead and reached 30°-40° beyond 

 the zenith. Unfortunately, although the sky was 

 clear and the meteor considerably exceeded Jupiter in 

 brightness, it left no visible trail. The meteor gave 

 the illusory impression of coming quite near to the 

 observer and not of describing a meridian, an effect 

 no doubt largely due to its increasing brilliancy. 



Comet 1916& (Wolf).^ — An investigation of the orbit 

 of this comet has been carried out by Messrs. R. T. 

 Crawford and Dinsmore Alter, of the Berkeley Astro- 

 nomical Department (Lick Obs. Bull., No. 282). From 

 this it appears that Prof. Barnard succeeded in 

 identifying the comet on a photograph taken on 

 April 24. The time of the observation indicates that 

 it must be the same photograph on which a confusion 

 of the minor planet 446 ^ternitas with the new 

 comet had been pointed out by the editors of the 

 Astronomisch Nachrichten (No. 4845). The earliest 

 position available to the American calculators was that 

 derived from Prof. Barnard's plate. With this and 

 other observations made at Yerkes, May loandMay 23, 

 the following differentially corrected parabolic orbit 

 has been calculated : — 



T=i9i7 June 16-4806 G.M.T. 

 cu=i2o= 37' 07-9'' ^1 = 183° 16' 58-8" 



/= 25° 40' 06*4" log ^ = 0226855 



These elements and the resulting ephemeris only 

 differ slightly from the calculations by Prof. _ A. 

 Berberich (Nature, June i). Numerous American 

 observations, mostly made at Yerkes, are represented 

 closely. The orbit resembles that of Wolf's periodic 

 comet 1884, III., and consequently an elliptic orbit 

 with a period of seven years was calculated; the 

 differences, however, disproved identity. The faint 

 luminosity and low altitude of the comet now prob- 

 ably put it out of reach until it becomes a morning 

 star. 



Arequipa PYRHELiOMETRY.^In consequence of the 

 recommendations of the Committee of the Inter- 

 national Union of Solar Research, measures of solar 

 radiation have been made at Arequipa since 1912. 

 Some of the results so far obtained have been pub- 

 lished by C. G. Abbot (Smithsonian Miscellaneous 

 Collection, vol. Ixv., No. 9). Special attention has 

 been given to the question of solar variability and 

 atmospheric transmission. At Arequipa the chief 

 factor in the latter connection is the amount of water 

 vapour, and consequently the silver-disc pyrheliometer 

 measures of radiation have been supplemented by a 

 nearly simultaneous series of measures of atmospheric 

 humidity. The monthly mean values show a close 

 connection between the solar radiation and vapour 

 pressure. This was represented by empirical formulae 

 which gave values of the solar constant in good agree- 

 ment with the more rigorous values obtained at 

 Mount Wilson and generally confirming the varia- 

 bility of the solar radiation. 



The dust of the Katmai eruption (June, 19 12") did 

 not affect the Arequipa measures. 



NO. 2437, VOL. 97] 



CANADIAN ECONOMIC GEOLOGY.^ 



''jTHE White River District of Yukon extends east 



■•■ from the Alaskan-Canadian boundary, and its 

 geology continues that of country well known by 

 the work of the American geologists. Some Carbon- 

 iferous rocks, resting on an Archean foundation, are 

 followed by thick Mesozoic sediments which contain a 

 few Cretaceous fossils. The Cainozoic is represented 

 by land and fresh-water beds containing lignites. As 

 in Alaska, there are two volcanic series, one of which 

 was erupted during the world-wide disturbances be- 

 tween the Jurassic and Cretaceous, and the other is 

 Upper Cainozoic and continued until very recent 

 though pre-Glacial times. In the early Pliocene the 

 country was uplifted and greatly fractured, the evi- 

 dence of which is most distinct on the coast. The 

 chief ores of the White River District are of gold 

 and copper. The discovery of the placer deposits at 

 Chisana in 1913 occasioned the greatest "stampede" 

 or mining rush since that to Klondyke in 1897-98. 

 The copper ores have long been worked by the 

 Indians, and in 189 1 the exaggerated reports of their 

 quantity led to the first prospecting of the country. 

 Mr. Cairnes's memoir is illustrated by some excellent 

 maps and photographs. 



At the opposite corner of Canada, on the southern 

 shore of the Northumberland Strait, is an area strik- 

 ingly unlike the White River District. It was one of 

 the first Canadian districts geologically investigated; 

 it was settled during the latter part of the eighteenth 

 century, and the names Arisaig, Knoj'dart, Moydart, 

 Lismore, etc., show that the pioneers were the ex- 

 patriated exiles from the western Highlands. The dis- 

 trict is composed of Palaeozoic rocks ranging from the 

 Ordovician to the Upper Carboniferous, with some 

 Ordovician rhyolite lavas and Upper Palaeozoic diabase 

 dykes. The surveys of recent years have supplemented 

 and in some respects corrected the earlier results of 

 Dawson and Honeyman. Thus there is a full Silu- 

 rian sequence, as the Moydart beds represent the 

 Wenlock series, which had been considered absent. 

 The Devonian is represented by the Knoydart series, 

 which is correlated with the British Lower Old Red 

 Sandstone. The absence of the Middle and Upper Old 

 Red Sandstone is attributed to great faulting, that 

 corresponds to that which caused the absence of the 

 Middle series from south-western Scotland. The 

 Carboniferous is represented, as in Britain, by a lower 

 marine series and an upper continental series. 



The most interesting economic deposits in this dis- 

 trict are the Silurian oolitic ironstones, which the 

 author infers from their special fauna were laid down 

 under unusual conditions, during which the sea con- 

 tained much ferruginous material. This view is not 

 adequately explained, and there is no proof that the 

 ores were not due to a partial replacement of an 

 oolitic limestone. The report is accompanied by two 

 clear geological maps. 



The oil discoveries in the United States in the early 

 'sixties stimulated research for oil in eastern Canada. 

 Oil was found, though in comparatively small quanti- 

 ties, and some of the districts continued to yield ever 

 since. This oil belt extends from Lake Huron to the 

 Gaspe peninsula, south of the mouth of the St. Law- 

 rence. The most important fields are in the south- 

 western peninsula of Ontario, south of a line from 

 the southern end of Lake Huron to the western end 

 of Lake Ontario. The oils come from various hori- 



1 D. r>. Cairnes: Uoper White River District, Yukon. Canada, Depart- 

 ment of Mines, GeoL Surv. Mem. 50, Geol. Ser., 51, 1915, "v. Pp- 191+xvii 

 ptates + 3 maps. 



M. Y. Williams : Arisaig-Antigonish District, Nova Scotia. ISi'a., Mem. 

 60. Geol. Ser., 47- iQi*- ^'- Pp- '73 + 2 maps. 



W. Malcolm : The Oil and Gas Fields of Ontario and Quebec. Itiet., 

 Mem. 81, Geol. Ser., 67, 1915, ii. Pp. 248. 



