February 15, 1900] 



NATURE 



371 



dwellers in the vicinity of Mancos and Cortes, Colorado, and also 

 near Aztec, Mexico, with the idea of reserving the lands as a 

 national park. This action has been taken as a result of an 

 agitation in Colorado for the protection of these ruins against 

 vandalist relic hunters. Some of the best preserved ruins have 

 been ruthlessly entered by curio hunters, who have broken 

 through walls and roofs and carried away the relics. It would 

 be a wise policy for the U. S. Government to have these ruins 

 guarded, so that they can be investigated by experts. For- 

 tunately, some of the best of them have not been tampered 

 with as yet. 



A NOTE upon recent improvements in the production of 

 electrolytic copper appears in Engineering^, and the following 

 ])articulars have been obtained from it. It is a comparatively 

 simple matter to get a good deposit of copper electrolytically, 

 provided always that a sufficiently low current density is used. 

 This, of course, involves a very large and expensive plant if 

 any reasonable output of the metal is desired. With greater 

 current densities difficulties make their appearance, and the 

 deposit, in place of being smooth and homogeneous, becomes 

 granular and lacks cohesion. By certain devices of one nature 

 or another, the troubles referred to above have been largely 

 "vercome. The effect of these is shown by the fact that lo 

 .ears ago an electrolytic bath for the deposition of copper 

 c<jmmonly contained 75 to loo times as much metal in solution 

 as was deposited in 24 hours. Nowadays these figures have 

 been reduced to one-fifth of the values stated. As a conse- 

 quence, the proportion of the metal obtained in the wet way 

 has been enormously increased, the world's production being now 

 estimated at 500 tons of electrolytic copper per diem. One of 

 the earlier plans of increasing the output was that introduced 

 by Elmore, in which an agate burnisher was caused to con- 

 tinuously pass over the surface on which the deposit was being 

 made. The resultant metal proved to be of extraordinary 

 strength. In a more recent development, a sheepskin impreg- 

 nated with animal fat is used as a burnisher. Quite recently 

 Mr. Sherard Cowper-Coles has hit upon another plan, in which 

 the copper is deposited on a vertical mandril, which is caused to 

 rotate at a very rapid rate. The centrifugal force developed 

 and the wash of the electrolyte over the rotatory surface keeps 

 the latter clean and free from gas, and as a consequence a 

 smooth and dense deposit has been obtained with current 

 densities approaching 200 amperes per square foot. An account 

 of the process, together with details of the mechanism used, will 

 be found in a paper recently read by Mr. Cowper -Coles before 

 the Institution of Electrical Engineers. 



The Deutscher Mathematiker \'ereinigung, which holds its 

 meetings concurrently with the Xaturforscherversammlung, has 

 published the report of its meeting at Munich last year. The 

 meeting was attended by about eighty members, and twenty- 

 two papers were read, including a discussion on the decimalisa- 

 tion of angles and of time. Upon the proposal of Prof Boltz- 

 mann, a committee wa= appointed to consider the terminology 

 of mathematical physics. The next meeting will be held at 

 -Vachen, in September 1900. 



Of the six first numerals in the Etruscan language, viz. max-, 

 eu, zal, hue, ci, s'a, it has been remarked by Prof. Thomsen, in 

 a communication to the Danish Academy, that we do not know 

 their precise order. M. E. Elia Lattes, writing in the 

 Rendiconli del R. Istituto Lombardo, discusses the value of the 

 numeral Qti, and the examination of old inscriptions in which 

 this word and its derivatives occur would appear in conformity 

 with the view previously expressed that Qu stood for " two." 

 NO. 1581, VOL. 61] 



In the Transactions of the Institution of Engineers aiKi'' 

 Shipbuilders in Scotland, xliii. (2)) (3), Mr. W. J. Luke dis- 

 cusses the means adapted for moderating the rolling of ships, 

 and in particular Froude's experimefits. The principal point 

 brought out by the paper, and the discussion on it, is the efficacy 

 of bilge keels in extinguishing rolling motion, a result no doubt 

 largely due to the discontinuous motion of the water past the 

 sharp edges of the keels in each swing of the ship. 



The Rendiconto of the Naples Academy, v. 8- r2, contains 

 the abstract of a paper by Prof. E. Ascione, on the properties of ' 

 conicoids with elliptic points, viz. the ellipsoid, hyperboloitt' 

 of two sheets, and elliptic paraboloid deduced' from projec- 

 tions made by taking an umbilicus as the vertex of conical 

 projection, and a plane parallej to the tangent plane at the 

 umbilicus as the plane of projection. The projections of the 

 focal conies are evidently circles, and the author finds that the 

 projections of the lines of curvature are obtainable by a simple 

 geometrical construction. The method, which includes stereo- 

 graphic projection of a sphere as a particular case, would 

 appear likely to lead to a number of not difficult problenrvs in 

 analytical solid geometry. 



The properties of certain radio active bodies form the subject 

 of a short note by M. Henri Becqu^rel [Compies rendtis, cxxix» 

 26, 1899). The nitrate of polonium, of which samples were pro- 

 vided by M. and Mme. Curie, was found to be nearly as active 

 as radium, both in its power of rendering air a conductor, and 

 in its action on a photographic plate ; but the radiation from this 

 compound did not experience any modifications in a magnetic^ 

 field, such as occurred with radium. When the polonium pre- 

 paration was placed in a magnetic field of from 4000 to io,ooa 

 C.G.S. units, the impressions obtained on a photographic plate 

 were just the same as when the field was absent. On the other 

 hand, the rays emitted by the radium when placed in the field 

 exhibited strong deviations, producing on a vertical plate im- 

 pressions bounded by spiral curves. The examination of 

 these curves enables an estimate to be made of the velocity of 

 propagation of radium rays. This velocity is compaiable with 

 the angular velocity due to a field of 4000 C.G.S. units, and 

 under plausible hypotheses give a velocity of propagation for 

 the radium rays of the same order as those which have been 

 found for the kathodic rays. 



SiGNOR G. GUGLIELMO describes in the Atti dei Lincei, 

 ix. I, certain modifications of the common hydrometer and of 

 Nicholson's hydrometer. His first suggestion is a device for 

 attaching movable weights to the common hydrometer with- 

 out the inconveniences arising from the immersion of these 

 weights in the fluid as in Sikes's form. A wire in the form 

 of an inverted U is attached to the top of the hydrometer, 

 and to its ends, which hang down outside the immersion jar, 

 the movable weights are attached, being disposed symmetri- 

 cally. The U -shape of the wire is, of course, necessary to 

 ensure stability. In conjunction with Nicholson's hydrometer^ 

 Signer Guglielmo recommends the use of a graduated pillar 

 for reading off small differences of density to avoid the diffi- 

 culties involved in immersing the instrument exactly to a fixed 

 mark. Finally, a " hydrostatic balance " is described, by 

 which is meant, not the hydrostatic balance of our text-books» 

 but a hydrometer adapted for weighing purjwses, as a substitute 

 for the common beam balance. 



The Weather Bureau of Washington has just issued a pre- 

 liminary report (Weather Bulletin, No. 208) on the kite ob- 

 servations of 1898, by H. C. Frankenfield, containing an, 

 interesting discussion of the vertical gradients of temperature^ 

 humidity and wind-direction at a number of stations in the 

 United States. The report deals with probably the largest 



