596 



NATURE 



[January 27, 19 ii 



"iron-shale." They are rounded or globular in 

 form but never angular, and have the same 

 " shaly " appearance as some of the sandstone 

 fragments. On examination they prove to be 

 oxidised masses of nickel-iron, and in some cases, 

 in spite of their alteration, the Widmanstatten 

 figures may be clearly recognised in them ; they 

 sometimes contain nuclei of unaltered nickel-iron. 

 The larger of the well-known Canyon Diablo 

 meteorites, which are of weights up to 300 or 

 even 1000 lb., show no trace of alteration, but 

 exhibit the pitted surfaces and other features of in- 

 dependent meteorites. Thus it would appear that 

 at this locality there were two types of meteorites, 

 one very easily acted upon by oxidation, and it is 

 possible that some of the smaller " Canyon Diablo 

 meteorites " may be only nuclei of the oxidisable 

 variety. 



All the American geologists who have studied 

 the locality are in agreement as to the non-volcanic 

 origin of this "crater"; Prof. G. K. Gilbert, 

 however, has suggested a theory which has found 

 wide acceptance. It is that the "crater" is due 

 to the impact of a great meteorite or group of 

 meteorites, which has produced the violent 

 mechanical effects everywhere visible. The only 



drive before it a "wad " of air capable of crushing 

 out the great circular cavity, while this same air,, 

 in its upward escape, would effect the upheaval 

 of the rocks of the rim and the ejection of 

 materials to distances up to two miles from it. 

 The problem of the existence of the great 

 meteorite at considerable depths or its gradual 

 disappearance by oxidation still remains. 



It is evident that the striking characters of this, 

 singular " crater " are of no less interest to- 

 astronomers^ — so suggestive are the characters in 

 which it agrees with the vast lunar craters — than 

 to geologists, who up to the present have been 

 chiefly attracted by the phenomenon. 



RECENT PUBLICATIONS OF THE CAPE 

 OBSERVATORY.^ 



ALTHOUGH Sir David Gill retired from the 

 direction of the Cape Observatory early in 

 1907, and died just seven years later, the volumes, 

 from that observatory which have recently been 

 distributed are essentially his work. Even in 

 the contributions of successor and collaborator 

 Gill's inspiration and design are evident. It is 

 not too much to say that the same spirit of energy 





GRIMESI DIAMETtW 0( CRATER W N.W. 10 t St. BtmG <1M0 FEET . 



Fig. 2.— Cross-section of crater along a line approximately N.W. to S.E. Scale, about i2goft.-i in. 



analogous case that can be cited — and it is a rather 

 remote one — is that of the meteorite of Knyahinya 

 in Hungary, which weighed 660 lb., and, accord- 

 ing to Haidinger, buried itself when it fell in 

 1866 to the depth of 17 ft., forming a circular 

 pit 4 ft. in diameter and 4J ft. deep. Coon Butte 

 may not unnaturally be accepted as supplying a 

 very suggestive explanation of the origin of the 

 far larger lunar craters which present so many 

 features in common with it. 



It must be confessed, however, that many un- 

 solved difficulties remain to prevent our unhesi- 

 tating acceptance of the meteoric theory. Chief 

 among these is the question of what has become 

 of the vast mass of matter capable of producing 

 the shattering impact. Only scattered fragments 

 of nickel-iron have been detected at the depths 

 reached by the borings, and the existence of a 

 vast mass of meteoric iron at greater depths finds 

 no confirmation from the magnetic observations 

 carried on in and around the "butte." In an 

 appendix to the memoir an account is given of 

 a striking suggestion on the subject by Prof. 

 H. N. Russell. He argues that a great meteorite 

 or group of meteorites, moving with planetary 

 velocities, would, on reaching our atmosphere, 

 NO. 2413, VOL. 96I 



and thoroughness will endure in the pages of 

 future publications long after his name has dis- 

 appeared from the title. No greater tribute can 

 be paid to the memory of a great man. His 

 personal achievement was considerable, but 

 beyond that his influence on others will surely 

 live. 



These three volumes are typical of the three 

 main currents to be observed in Gill's purely 

 astronomical work. There is a zone of the Cape 

 Astrographic Catalogue, a contribution to the 

 great scheme of registering the positions of the 

 stars by photography, with the inception and j 

 execution of which Gill was so largely identified, i 

 There is a volume of meridian work dealing both > 

 with the old transit circle and the new instru- j 



1 Cape Astrographic Zones. Vol. ii.. Catalogue of Recfaneular Co- | 

 ordinates and Diameters of Star-Imaees derived from Photoaraphs taken at 

 the Royal Observatory, Capeof Good Hope, commenced under the direction 

 of Sir David Gill, completed and prepared for press under the supervision of 

 S. S. Hough. Zone -42°. (Edinburgh : H.M.S.O. ; London: Wymanand 

 Sons, Ltd., 19T4.) Prire 20s. 



Results of Meridian Observations of Stars made at the Royal Observa- 

 tory, Cape of Good Hope, in the Years 1905 to 1908, under the direction of 

 Sir David Gill and S. S. Hough. (Edinburgh: H.M.S.O.; London: 

 Wyman and Sons, Ltd., 1914.) Price 30.?. 



Annals of the Cape Observatory. Vol. xii.. Part i. Determination of fbe 

 Mass of Jupiter and Elements of the Orbits of its Satellites from Observa- 

 tions made with the Cape Heliometer by Sir David Gill and W. H. 

 Finlay. Reduced and discussed by Dr. W. De Sitter. Pp. 173. (Edin- 

 burgh : H.M.S.O. ; London : Wymanand Sons, Ltd., 1915.) Price 6s. 



