420 



NATURE 



[January 26, 191 1 



be rejected, and would have cost more than the total out- 

 Jay on the Department." 



In response to the strong recommendations of the Royal 

 "Commission, the Imperial Government has recently agreed 

 in principle to the continued maintenance of the central 

 •office of the department for a further period of ten yetirs 

 from April i. This will enable the department under Dr. 

 Watts (the present Commissioner) to continue to coordinate 

 the work of scientific agriculture in the \>''est Indies, to 

 .carry on research, and afford still further assistance in 

 ^developing the resources of the colonies. 



THE P^AT^Mi CAHAL IN 19 lo.* 



'X'HE canal now being constructed by the American 

 •*■ Government in continuation of the work commenced 

 .by de Lesseps is 503 miles long from deep water in the 

 "Caribbean to deep water in the Pacific. Of this distance 

 34 miles is high-level with 8 miles sea-level at each end, 

 as shown on the accompanying profile. The water for 

 lockage is supplied by blocking the lower valley of the 

 Chagres River at Gatun with an earthen dam 7000 feet 

 long, 115 feet high, and about 2000 feet broad. This 

 consists of two heaps of broken rock enclosing the 

 hydraulic fill, i.e. silt pumped in wet and allowed to 

 <lrain. This packs tightly under the pressure of the atmo- 

 sphere, and secures the impermeability of the dam. The 

 heavy rock fills secure its stability against the lateral 

 pressure of the 85 feet of water which will be behind the 



is overlaid with disintegrated rock and with clay to an 

 average thickness of 15 to 20 feet, and the rock 'itself in 

 places has open joints or seams, either vertical or sloping 

 towards the cut. Frequently the first sign of a landslide 

 is the bulging up or humping of the basalt rock at the 

 bottom of the cut, which sometimes rises 20 feet. 

 Simultaneously a crack appears on the soil above, which 

 is followed by foundering of the soil and clay, and very 

 often of the rock. Obviously, so long as humping of the 

 bottom occurs, it would be futile to let in water, as the 

 canal might be at any moment so reduced in depth as to 

 be unnavigable. It is proposed to deal with the difficulty 

 by flattening the slopes until gravitational equilibrium is 

 achieved, on the principle already referred to in the case 

 of the Gatun dam. 



The author points out the existence of a gravitative 

 wave in landslides, and recommends the application of the 

 principjes and terminology of surface waves to their study. 



In spite of the difficulty of the landslides, the opening 

 of the canal may be expected on the promised date, viz. 

 January i, 1915. 



APPLIED GEOLOGY IN THE UNITED 

 STATES^ 



HE eight bulletins referred to below cover a wide 



range of applied geology, and contain many valuable 



additions to academic geology. Thus the memoir by 



Messrs. Hillebrand and Schaller is a most important con- 



ATLANTIC 

 DIVISION 



CENTRAL DiyiSION 



31-7 Miles 



PACIFIC DIVISION 



14 16 18 20 22 24 26 28 30 32 34 36 

 The Vertical Scale is exaggerated One Hundred Times , 



Profile of Panama Canal. 



•dam. The height now attained by the dam is 70 feet. 

 The underlying ground is somewhat soft, but it has not 

 been squeezed up owing to-^e way the load has been 

 -spread. The sides of the dam, in fact, hold down the 

 iground so that the weight of the central portion cannot 

 squeeze it up. 



The elaborate investigations of the engineers on the spot 

 have shown that the foundations are impervious, the 

 -earlier official reports to the contrary having been based 

 upon a misinterpretation of the borings. The area of the 

 lake which will be maintained between this dam and 

 that at Pedro Miguel will be 164 square miles, or twice 

 the size of the Lago Maggiore. 



The dimensions of the locks are : length, 1000 feet ; 

 breadth, no feet. The minimum depths in canal and 

 locks will be 41 feet. The minimum bottom width in 

 the 8 miles of the Culebra cut, 300 feet. The rest of the 

 canal will have a bottom width of from 500 to 1000 feet. 

 The profile shows the greatest original elevation of the 

 ground to be 312 feet, but this is on the central line. On 

 the eastern side at the same place the escarpment began 

 at 534 feet. The bottom will he at 40 feet above mean 

 sea-level, so that the cutting here will be nearly 500 feet 

 deep. The depth of water in this portion of the canal will 

 be 45 feet, the surface being therefore 85 feet above mean 

 sea-level. 



The principal difficulty in construction is caused by 

 landslides, brought about by the action of rain, of which 

 •90 inches falls in the year at Culebra. The basalt rock 



1 Ab.';tract of a paper read before the Royal Society of Arts on December g 

 "by Dr. Vaughan Cornish. 



NO. 2152, VOL. 85]' 



tribution to knowledge of the minerals containing mercury. 

 It gives the result of a thorough research on kleinite, 

 montroydite, terlinguaite, and eglestonite. The two last 

 are proved to be .oxychlorides, and montroydite to be an 

 oxide of mercury, confirming the conclusions of Prof. 

 Moses, the founder of these species. Kleinite was named 

 in 1905 by Prof. Sachs, who described it as . an oxy- 

 chloride of mercury, but the day after his paper was 



1 F. C. Schrader : Mineral Deposits of the Cerbat Range, Black Moun- 

 tains, and Grand Wash Cliffs, Mohave County, Arizona. U.S. Geo!. 

 Survey, Bull. 397. Pp. 226+xvi plates + 37 figs. (Washington, 1909.) 



E. F. Burchard and C. Butts : Iron Ores, Fuels, and Flu xes of the Birm- 

 ingham District, Alabama, with chapters on the Origin of the Ores, by 

 Edwin C. Eckel. U.S. Geol. Survey, Buli. 400. Pp. 204 + + xvii plates, 

 -|-ig fiss. (Washington, 1910.) 



W. F. Hillebrand and W. T. Schaller : The Mercury Minerals from 

 Terlingua, Texas. U.S. Geol. Survey, Bull. 405. Pp. 174+ vi plates +44 

 figs. (Washington, 1909.) 



W. H. Emmons : A Reconnaissance of some Mining Camps in Elko, 

 Lander, and Eureka Counties, Nevada. U..*^. Geol. Survey, Bull. 408. 

 Pp. 130+v plates4-22 figs. (Washington, 1910.) 



A. G. Maddren : The Innoko Gold-Placer District, Alaska, with Accounts 

 of the Central Kiiskokwim Valley and the Ruby Creek and Gold Hill 

 Placets. U.S. Geol. Survey, Bull. 410. Pp. 87-l-v plates. (Washington, 

 1910.) 



F. L. Hess : A Reconnaissance of the Gypsum Deposits of California, 

 \vith a Note on Errors in the Chemical Analysis of Gypsum, by George 

 Steiger. U.S. Geol. Survey, Bull. 413. Pp. 37-|-iv plates-l-2 figs. (Wash- 

 ington, 1910.) 



F. L. Ransome : Notes on some Mining Districts in Humboldt County, 

 Nevada. U.S. Geol. Survey, Bull. 414. Pp. 75-{-i plate-t-y figs. (Wash 

 ington, 1909.) r ,^ I 



The Valuation of Public Coal Lands. G. H. Ashley : The Value of Coal 

 Land. C. A. Fisher : Depth and Minimum Thickness of Beds as Limiting 

 Factors in Valuation. U.S. Geol. Survey, Bull. 424- Pp- 75- (Washmgton, 

 1910.) 



