550 



NATURE 



[October 7, 1897 



Lama stopped the executioner, and commuted the sentence of 

 decapitation to the torture of the stretching log— a kind of rack 

 upon which Mr. Landor was chained for eight days — after which 

 he was released. Mr. Landor has now returned to India, 

 suffering from the effects of the torture to which he was 

 subjected, and which he half anticipated before he set out upon 

 his hazardous journey. 



A CURIOUS illustration of the power of light matter to per- 

 forate more substantial substances when driven at a high 

 velocity is stated by the Engineer to have occurred in the Royal 

 Arsenal a few days ago. In the course of experiments on firing 

 gas in piines, conducted by Captain Cooper Key, R. A., under the 

 Home Office, a special gun is employed to do duty for a bore- 

 hole with a charge of high explosive, and pressed cylinders of 

 raw dry clay 3 in. long and ig in. in diameter are used to repre- 

 sent tamping. These "shots" are made to act in various mix- 

 tures of air, coal-dust, gas, «S:c., and to stop the course of plug, 

 &c., eventually, a cast-iron target plate, i in. thick, was placed 

 25 ft. in front, at an angle of 45°, in order to break up every- 

 thing into dust and throw it upwards. After three or four shots 

 with this arrangement the clay plug, weighing 7| ozs., per- 

 forated the inch iron plate, and the hole thus made has been 

 steadily extended since. The familiar tallow candle passing 

 through a door must hide its head before a 7i-oz. plug of clay 

 perforating an iron plate an inch thick at an angle of 45°. 

 Doubtless the velocity must be tremendous. It is pointed out 

 that the velocity for a hard cylinder of this weight and size to cut 

 through an inch of wrought iron at 45° would be over 1800 foot- 

 seconds. With cast-iron and clay and the three or four repeated 

 blows, everything is so greatly altered that there is little more 

 to be said than that the effect is remarkable and unexpected. 



An important contribution to the controversy respecting the 

 great Alpine double fold has been issued by Dr. Rolhpletz of 

 Munich, in the last number of the Zeit. dent. geol. Gesell. (vol. 

 xlix. pp. 1-17). In this paper Rothpletz examines in detail the 

 evidence which led the orthodox school of Swiss geologists to 

 the belief that the Gliirnisch massif has been formed by a double 

 fold. It is well known from Heim's great work, the " Mecha- 

 nismus der Gebirgsbildung," that the summit of the Glarnisch 

 consists of Lower Cretaceous rocks, which rest on deposits be- 

 longing to a later part of the same system. Baltzer accordingly 

 explained this inversion by a complex series of folds and douljle 

 folds. Rothpletz, however, by a magnificent piece of detailed 

 field-work, has shown that the arrangement can be more easily 

 explained as a case of over-thrust faulting. The Glarnisch, it 

 may be added, stands on the western border of the mountain 

 group, whose complicated structure Ileim's double-fold of 

 Glarus was invoked to explain. 



A SYNOPSIS of a report on an experimental boring for petro- 

 leum, carried out by Mr. W. A. Fraser at Athabasca Landing, 

 Alberta district, is given by Dr. G. M. Dawson in the Annual Re- 

 port (vol. viii. ) recently issued by the Geological Survey of Canada. 

 Where the basal sandstone of the Cretaceous formation comes 

 to the surface, about 130 miles north of the place of the boring 

 on the Athabasca River, it is charged with bituminous matter, 

 and from the observed dip of the Cretaceous rocks it was hoped 

 that these " tar sands " would be found at a depth of from 1200 

 to 1500 feet. This estimate has proved to be a little under the 

 mark, but the work that has been done indicates that the top of 

 the tar sands should be reached at about 1800 feet. When 

 Dr. Dawson visited the boring, a depth of 1731 feet had been 

 reached, and it was proposed to continue down to 2000 feet, so 

 as not only to pass through the tar sands, but also to penetrate, for 

 some distance, the rocks — presumably limestones of Devonian age 

 — underlying them. It is pointed out that there can be no reason- 

 able doubt that an important oil-field exists in northern Alberta 

 NO. 1458, VOL. 56] 



and Athabasca, and the facts gained by the experimental boring of 

 the Canadian Geological Survey has rendered it possible to esti- 

 mate very closely the depth at which the tar sands may be looked 

 for along the Athabasca Valley for a distance of about 150 miles. 

 The development of deposits »f petroleum in this region is of such 

 great importance that Dr. Dawson should not lack support in 

 the plan he advocates of sinking several experimental wells simul- 

 taneously in different parts of the great area, which the geological 

 conditions show to be favourable to the occurrence of petroleum 

 in quantities of commercial value. 



The Explosives Department of the Home Office has (says 

 the Times) recently had under consideration the question of the 

 restrictions to be applied to the manufacture and keeping of 

 acetylene gas, and has conducted various experiments with the 

 object of gaining information on this matter. The results show 

 conclusively that acetylene ga.s per se, when under a pressure of 

 something less than two atmospheres, is violently explosive ; 

 whereas at a pressure less than one a half atmospheres it appears 

 to be reasonably free from liability to explosion, provided it is 

 not admixed with oxygen or atmospheric air. For commercial 

 and practical purposes it is considered sufficient to allow a pressure 

 of 20 inches of water above that of the atmosphere (i.e. roughly 

 about one and one-twentieth atmospheres), and it is accordingly 

 proposed to draw the safety line at this point, and to declare 

 acetylene when subject to a higher pressure to be an "explosive " 

 within the meaning of the Explosives Act, 1875. ^^ France 

 and Germany, the authorities have fixed the limit of danger at 

 one and a half and one and one-tenth atmospheres respectively, 

 and have imposed prohibitions or restrictions on the keeping or 

 manufacture of the gas when it is at a higher pressure. 



Dr. Al. Bludau publishes in Petermann^ s Mittheilungen 

 (viii. 1897) a second instalment of his work on the measurement 

 of the great drainage basins of the world. Dealing this time 

 with Africa, he discusses in detail some of the divisions offering 

 special difficulty in definition, and finds that of the total area of 

 29'3 millions of square kilometres, 36 per cent, drain to the 

 Atlantic, 15 per cent, to the Mediterranean, and 18 per cent, to 

 the Indian Ocean, while the neutral regions form the remaining 

 31 per cent., the Sahara alone occupying six and three-quarter 

 millions of square kilometres. 



A BRIEF preliminary report by the surviving officers of the 

 second Bottego Expedition in Somaliland, Lieuts. Vannutelli 

 and Citerni, with a route map, is contained in a recent 

 bulletin of the Italian Geographical Society. The expedition 

 started from Brava in October 1895, ^"d reached the north end 

 of Lake Rudolf in August 1896, whence Dr. Sacchi set out in 

 the November following, intending to return southwards with 

 the zoological and ethnographical collections ; his fate seems 

 still very uncertain. The main body of the expedition left the 

 camp on Lake Rudolf about the same time, and skirted the 

 Ethiopian highlands, travelling in a north-westerly direction ; 

 but owing to the unhealthy climate Captain Bottego was com- 

 pelledrto make for the mountains, where he had dealings with the 

 chief of Lega and Sajo, who, however, proved treacherous, and 

 in the fight which ensued Captain Bottego lost his life. The 

 survivors were kept prisoners for a time, but were ultimately 

 sent to Adis Abeba by the Emp eror Menelik. 



In the Bolletlino della Societa geografica Italiana, Signor G. 

 Roncagli discusses the tides of the Straits of Magellan between 

 Cape de las Virgines and Punta Arenas, the special question 

 being the retardation of the tidal stream by some three hours 

 in mid-channel, compared with the shore on either side, first 

 pointed out by King and Fitzroy. He suggests as an explana- 

 tion of the phenomenon, that on account of the peculiar shape 

 of the channel a gravity current is superposed on 'the normal 



