tight subdivision means a certain loss in comfort in interior accommodation. In all such matters it is a question of give and take, of arriving at a solution that is a practical one. From the likelihood that when needed lifeboats may be found impossible of operation, witness the recent Volturno disaster, it seems that the important lines of progress are: (1) making vessels as capable as practicable of withstanding damage by collision; (2) providing them with the best obtain shore stations and other vessels, wireless telegraphy, the submarine bell and signal, and the like; and (3) providing a sufficient and efficient crew of officers and men, who shall be unhampered in their duties by any instructions looking toward record passages at the risk of safety. It is of the utmost importance that the vessels of all nations should, so far as possible, be subject to the same laws and restrictions in these matters, and international conferences are being held with this object in view. and 12 minutes. Her passenger list, who travel on the sea. Added lifeincluded 350 first-class, 400 second- boat capacity means reduced space class, 1,000 third-class, and 1,700 on the promenade deck; further watersteerage, a total of 3,450. The best run was 556 miles from noon to noon, and her best hourly speed was 23 knots. This vessel, the largest in the world at the present time, is 919 ft. in length and 98 ft. beam; her gross tonnage is 50,000, and her contract speed of 221⁄2 knots is secured with turbines developing 63,000 h. p. The bridge is 90 ft. above water. Her masts measure 246 ft. from keel to truck. The funnels extend 70 ft. above the upper deck and about 32 ft. in fore and aft direction, 18 ft. in diam-able means of communication with eter. She carries 83 lifeboats and two motor launches which are equipped with wireless apparatus having a range of 200 miles. The vessel itself has a wireless apparatus with a range of 1,500 miles, and carries three wireless operators. She carries one anchor of 26,500 lbs., two others of 17,600 lbs., and a fourth of 11,500 lbs. Seven decks out of a total of ten are devoted to the use of the first-cabin passengers, and there are many large saloons and living rooms. There are four electric elevators for passengers and five freight elevators. A Roman bath two stories in height, with a pool 39 by 21 ft., having nine feet of water, The new Hamburg-American liner Vaterland was launched during the month of April. The enormous size of this vessel may be estimated from the fact that her tonnage will be 55,000, or 5,000 tons in excess of the Imperator, and her passenger capacity will be 4,050. During the same month the new Cunarder Aquitania was also launched, and although not so large as the Hamburg-American vessel, her dimensions show a considerable in crease over the Mauretania and Lusitania, the present largest Cunarders. The Aquitania, 901 ft. long, 97 ft. beam, has a tonnage of 47,000; her speed will be 23 knots, and her passenger capacity 3,250. Safety at Sea.-As a direct result of the tragic fate of the Titanic a widespread demand for investigation of all matters relating to safety at sea has borne definite fruit. Quite naturally some of the resultant changes are now criticised by those is a remarkable feature. It is interesting to note that as a direct result of the Titanic disaster, her sister ship the Olympic was rebuilt at an enormous expense, an inner skin added, forming a complete double hull extending to a considerable height above the water-line, a feature that has been also provided for in the other large trans-Atlantic passenger vessels whose construction was commenced subsequent to the Titanio disaster. The revised rules of the British Board of Trade relating to life-saving appliances on board ship, tentatively announced in September, 1912 (A. Y. B., 1912, p. 57), went into effect on March 1. All foreign-going passenger steamers are now required to carry lifeboats sufficient in number and capacity to accommodate the total number of persons which each ship is certified to carry. As to the location of davits, the type of lifeboat authorized and the provision of pontoon rafts, the new rules follow the recommendations of the special committee of the Board of Trade appointed after the Titanic disaster to consider the ques tion of lifeboats and davits (ibid.), | to securing maximum efficiency, wherewhich presented an interim report as in the direct-drive turbine installaearly in January. Marine Engineering.-The tendency of marine-engine design in this country still indicates a distinct leaning toward the well known and the conservative. Other nations are spending large sums, and with excellent results, in the development and manufacture of Diesel engines. With us, if we eliminate Government vessels, the Diesel engines in operation or contemplated are but few. With the turbine situation it is much the same. The advantages of the turbine, either geared or not, or in combination with reciprocating engines in certain special cases, have been more fully recognized by the naval authorities than by the operators of commercial vessels; if the naval turbine-driven vessels are eliminated, but few others can be found. tions the necessary restrictions on shaft revolutions generally make it impossible to secure the best results from the, turbine. The use of oil fuel, with consequent economic advantages, is becoming more and more general, not only in the Navy, but in all classes of steam vessels. Yachting. The past season of 1913 has seen somewhat of a revival in the building of steam yachts, more vessels of this class having been added to the fleet during the year or placed under construction than for many years past. For several years the possibilities of the gasoline or the Diesel engine have held out great inducements, and caused steam to be looked upon as old fashioned. With the increase in cost of gasoline and the present high first cost of Diesel engines, many have come to the conTurbine builders are concentrating clusion that steam engines, preferably their efforts on the development of with oil-fired boilers, will for some reduction gearing with very consid-years at least be the most satisfactory erable success. The geared turbine, prime movers. The certainty of intercertainly for marine work, possesses national races for the America Cup so many advantages that unquestion in 1914 has undoubtedly had a stimably it has come to stay in one formulating effect upon those interested or another. Its use permits the selec-in yachts and yachting, and the tion of proper propeller dimensions, as progress on the Panama Canal and the shaft revolutions can be adjusted the removal of the duty on foreignto suit any particular case, and at the built yachts are contributing causes same time the design of the turbine working for renewed activity in this itself can be carried out with a view sport. PHYSICAL PROPERTIES OF METALS AND ALLOYS WILLIAM CAMPBELL Structure of Metals.-The old idea of the structure of a metal was based on its fracture; from this came the terms, crystalline, granular, fibrous, and amorphous. The microscope has proved, however, that all metals are crystalline, and that the structure revealed by fracture may have no relation to the structure of the metal, and depends not only on the method of breaking, but also on the mechanical and thermal treatment. All metals are built up of crystalline grains with distinct orientation, the size and shape depending chiefly on the rate of solidification and the mass of the metal. The structure shows no change when strained within the elastic limit, but when once this is passed there is a permanent deformation, and within the grains themselves we find sliplines and slip-bands, which increase in number as the strain increases, until finally the grains are distorted and broken down, and the structure becomes composed of a broken-up conglomerate. The elastic limit is greatly increased thereby and the metal is much harder, but the ductility, as a rule, falls off. On annealing such a strained metal the crystals or grains grow with distinct polygonal boundaries and are generally twinned, the size depending on the time and temperature of annealing, the amount of work the metal has undergone, and reaches a minimum at what may be called the complete annealing temperature of the metal. Following the theory that amorphous modifications of metals exist, when a metal is perfectly annealed it consists of an aggregate of crystals surrounded by a strong and flexible upon its cross-section. The strength falls off, the metal becomes comparatively soft, and its ductility increases. The recent researches of Beilby (Jour. Inst. of Metals, VI, 5) tend to confirm his theory that cold working of a metal produces an amorphous modification on the surfaces of the slip-lines and slip-bands, which modi-ground mass or cement of amorphous fication is harder and stronger than the original crystalline one. Reheating to temperatures around 300 deg. C. causes the transformation from amorphous to crystalline state. Of interest in this connection is Quincke's hypoth- Constitution of Alloys.-The rapid esis of the foam structure of metals advance in our knowledge of alloys (Int. Zeitschr. für Metallographie, is in main due to metallography. For III, 23), and Cohen's views on the so-called "strain disease of metals" (Zeitschr. für Elektrochemie, XIX, 19). Fusibility of Metals.-The melting points of metals have now been determined with great accuracy and are given by Burgess in Circular 35 of the Bureau of Standards. Hardness. Much confusion exists as to the hardness of metals, because we may have several different kinds, such as resistance to scratching, cutting, indentation, permanent deformation, or to elastic impact. For the measurement of indentation hardness the Brinell machine is in general use, whereby a hardened steel ball, usually 10 mm. in diameter, is forced into the metal under a load of 3,000 kg. for iron and steel, or 500 kg. for softer metals, and the hardness number calculated from the spherical area of the depression formed. The Shore scleroscope measures the rebound of a hard body from the surface of the metal to be tested and the height of the rebound gives the measure of hardness. Both of these instruments are used to measure the difference in hardness between different m、tals and also of the same metal after different mechanical and heat treatment. Galy-Aché (Revue de Metallurgie, X, 585) reviews our knowledge of the cold-working of metals. Mechanical hardening does not occur until the elastic limit has been reached and permanent deformation takes place. The elastic limit is raised thereby by an amount proportional to the force producing the deformation. Reheating decreases the hardness, which metal. Then the amorphous cement takes up the elastic deformations, while the crystals yield to permanent deformations by slip-lines and slipbands. most of the binary and many of the ternary alloys the complete thermal diagrams have been worked out, whereby we see the relation between temperature and composition and the changes which take place not only when an alloy passes from the liquid to the solid state, but also in the solid condition. The constitution of iron and steel has been the subject of much work, and the different ideas are set forth in the diagrams of Benedicks, Goerens, Upton, and Ruff (Howe, Bull. Am. Inst. Min. Engrs., 1912, p. 1181). Iron is capable of holding 1.7 to 2 per cent. of carbon in solid solution (austenite), but with fall of temperature this solid solution tends to break down into pure iron (ferrite) and carbide of iron (cementite). By rapid cooling, as by quenching, much of the carbon can be held in solution and the metal is hardened thereby. Tempering tends to break down the solid-solution austenite into transition products, martensite, troostite, sorbite, etc., the constitution of which continues to be a source of much work and discussion. When there is more than two per cent. of carbon present the excess is found either as cementite or graphite, depending primarily on the rate of freezing and cooling. There are two main theories. The one states that we have two systems, the austenite-cementite or metastable, the austenite-graphite or stable. Goerens thinks that all irons freeze as austenite-cementite and that graphite is the product of the decomposition of cementite. The constitution of the copper-zinc alloys (brasses) has been worked out by Shepherd and by Carpenter and their tensile strength by Lohr (Jour, Physical Chem., XVII, 1). Up to about 36 per cent. of zinc the alloys are homogenous solid solutions (alpha); beyond this point a second solid solution, beta, makes its appearance, and at 47 per cent. zinc the alloy is entirely beta. Carpenter (Jour. Inst. of Metals, VII, 70) has shown that just about 450 deg. C. the beta tends to break down into alpha, and a third solid solution, gamma. The maximum strength is in the beta region at 45 per cent. zinc and is about 31.7 tons per square inch. The copper-tin alloys have been worked out by Heycock and Neville and by Shepherd, and a new transformation in the solid state is recorded by Hoyt (Inst. of Metals, Ghent meeting, 1913). They resemble the brasses in that up to about 10 per cent. of tin the alloys are homogeneous solid solutions, but when the tin is increased a second solid solution, beta, comes in; this beta breaks down into alpha and a third solid solution, gamma, at about 450 deg. C. Hence the properties of the brasses and the bronzes, like steel, can be profoundly modified by heat-treatment. German silver is a white ductile alloy containing 55 to 60 per cent. copper, 15 to 20 per cent. nickel, and 20 to 30 per cent. zinc, and consists of crystals or grains of a single solid solution. Hudson (Jour. Inst. of Metals, IX, 109) has studied the effect of annealing and found that one hour at 800 deg. C. was insufficient to get rid of the "cored" structure, but one hour at 900 deg. C. was sufficient to produce a homogeneous alloy. manganese are similar, while the alloys of iron, manganese, and copper are somewhat more complicated because iron and copper are not completely soluble in each other in the solid. Hence two distinct constituents are found in many of the alloys. Rosenhain and Archbutt (Proc. Institution Mech. Engrs., 1912, 319) have worked out the aluminium-zinc diagram together with the physical properties. They were able to roll and draw an alloy with 25 per cent. zinc. An alloy with 25 per cent. zinc and three per cent. copper gave a hotrolled bar with 30.9 tons per square inch tensile strength and an elongation of nearly 17 per cent. -- Magnetic Permeability. — In 1903 Heussler prepared alloys of copper, manganese, and aluminium and found them to be magnetic. This magnetism was explained by a ternary compound. Ross (Trans. Faraday Soc., VIII, 185) puts forward the theory that the alloys consist of solid solutions of the binary compounds Cu, Al and Mn, Al, but Rosenhain has shown that the alloys of aluminium and manganese alone are strongly magnetic. Electric Conductivity. The variation in electric conductivity of alloys is at once made clear when the thermal diagram is considered. Guertler's work (Jour. Inst. of Metals, VI, 135) shows that the conductivity of alloys composed of solid solutions or mechanical mixtures of the metals increases as the temperature rises, while that of intermetallic compounds decreases. Corrosion.-The corrosion of brass has been the subject of a good deal of research. Two causes have been assigned. First, when the alloys are composed of the two constituents alpha and beta, there is a difference of potential between the two, the beta becomes the anode and is destroyed through the zine going into solution, leaving a porous mass of copper behind. Second, when the alloy con H. S. and J. S. G. Primrose (ibid., 158) subjected Admiralty gun metal (copper 88, tin 10, zinc 2) to heat treatment and found that simple annealing for 30 minutes at 700 deg. C. gave a maximum increase in strength and elongation, and the homogeneity and other properties were improved. The ternary alloys of nickel, man-sits of homogeneous alpha, a differganese, and copper have been found by Parravano (Gazzetta Chim. Ital., XLII, ii, 367, 385, 513) to consist of homogeneous solid solutions and heterogeneous structure in these alloys is due to imperfect diffusion. The ternary alloys of iron, nickel, and ence of potential may be set up by adherent impurities on the surface or by strain, and corrosion begins through electrolysis. When once begun, the presence of metallic copper, which becomes the cathode to the alpha solid solution, hastens the corrosion. XXIV. MATHEMATICS AND ASTRONOMY MATHEMATICS E. B. WILSON somewhat general nature, containing some original articles, many book reviews, and personal notes. This year Prof. M. Bocher (Harvard) has retired from the position of editor-inchief of the Transactions; Prof. L. E. Dickson (Chicago) succeeds him. The management of the Monthly has been completely changed; Prof. H. E. Slaught (Chicago) has been made managing editor and, with the coöperation of his associates, is making a strenuous campaign on behalf of the enlarged and improved Monthly. Annual Production. Many per- est to teachers in the better grade sons believe that mathematics is a of high schools and to undergradudead science and that the mathe- ate students. The Bulletin is of matician, like the teacher of Greek and Latin, does but go over accomplishments of the past. Even those who know that mathematical doctrines are constantly advancing have often but a small idea of the amount of research published. The Jahrbuch über die Fortschritte der Mathematik is an annual publication which lists all the titles of mathematical work coming to the attention of the editors, with brief synopses of most of the original articles. So large is the task of assembling the material that this authoritative review of mathematical investigation is always three years behind. Volume XLI, covering the year 1910, appeared in 1913; it lists about 3,700 titles and contains 1,054 pages, exclusive of indices and prefatory matter. Path of Falling Bodies.-Since the time of Gauss and Laplace, a century ago, the question of the path followed by a body falling from a moderate height above the surface of the ground has been subject to theoretical and experimental investigation. A body released at a In the United States the Trans- height does not follow an exactly actions of the American Mathemati- vertical path; for, as the earth turns cal Society, the Bulletin of the So- on its axis, a point such as the top ciety, the American Journal of of the Eiffel tower, being farther Mathematics, the Annals of Mathe- than the base from the axis, and matics and the American Mathe- having the same angular velocity as matical Monthly, are the five lead- the base, is moving faster than the ing periodicals devoted exclusive- point on the surface of the ground ly to mathematics; they print in the immediately beneath. Hence a body neighborhood of 2,000 pages annually. released from the top has an easterly The Transactions and the Journal velocity in excess of the velocity of appeal only to the highly trained the point vertically underneath, and professional mathematician inter- consequently falls to the east of the ested in advanced research. The vertical. This chief part of the Annals aims to provide material in- phenomenon has long been known telligible to a large range of gradu- both theoretically and experimentate students and teachers of ordinary ally. The question has been raised collegiate courses in mathematics. whether the body does not also deviThe Monthly is still less technical ate slightly either to the north or and contains much that is of inter- south. The earlier mathematicians |