CRYSTALLOGRAPHY

the geometry of the ex- ternal forms of crystals has been completely worked out. the 32 crystal-classes differing from one another in their type and degree of symmetry and the six crystal-systems into which these classes can be grouped are now well established. the same is also true of the geomctrical conceptions of the internal structure of crystals. there are 230 possible types of homogeneous point- systems, referable to 14 kinds of space-lattices. attempts have been made to trace a connection between the internal structure of crystals and their chemical constitution. here there is ample scope for speculation; but since 1912, when x-rays provided a new method of investigation, some real advance has been made. by this method it is possible not only to determine the internal structure of crystals, but also actually to measure the distances between the atoms. 795 crystals consist of a homogeneous assemblage of particles, which are marshalled in certain definite ways. the grouping around any one particle (except those on the boundaries of the crystal) is the same as that around every other particle of the same kind. further, the particles are arranged at regular inter- vals along straight lines. throughout the structure there are fic. 1.—simple cubic space lattice. several parallel sets of such lines, and these lie in several parallel sets of planes also at regular intervals apart. an example of such a structure is the simple cubic space- lattice represented tn fig. r. here the particles (all of the same kind) are placed at equal distances, say @, along parallel lines in three sets at right angles; the distance between the parallel lines in each plane and between the parallel plancs of lines being also a. that is, the particles are situated at the points of intersection of a system of lines that form a square network or lattice in three dimensions. or the structure may be regarded as a stack of small cubes each with a quarter of a particle at every corner; the four adjoining cubes at each corner then providing the whole particle. in this grouping, any one particle is surrounded by a set of 6 similar particles at distance a; further, it is surrounded by 12 particles at distance ¥ 2u (i.e., the diagonal of the square); and by eight other particles at distance v 3a (i.e., the diagonal of the cube). it is clear from fig. r that the three sets of lines are parallel to the edges of the cube, and that they lic in planes parallel to the e? eo? aioe e o* 2.¢° ae e e* ae ‘ ee @\e @ ee e e* e * le? « e ee e e e e¢,¢ 6 @ ° @ a rs s ® p e «e's «6 6 oa o* _»® ee e° eo x e e® *ee e©eeee ° e \ \ oe id e* ] m6 6. 6. e © 6. 6 ae le ‘ . @ eo? ® @ @'e e© oes e* \ % oe @ e e e @\e se 6 \ \ e®eeeehee = — c ;. 2.—~arrangement of points on surface of cubie crystal. 766 faces of the cube. but the particles also lie in other sets of parallel lines, which fall in other sets of parallel planes. certain of these additional lines and planes of particles are represented more prominently in fig. 2, which is drawn on a smaller scale with a larger number of particles (but to avoid confusion only those on the surface of the solid are marked). in this figure the three front edges of a portion of the main cube are truncated by planes of the rhombic-dodecahedron, and one corner has been cut off symmetrically by a face of the octahedron. (since the octahedron face intersects both the cube and the rhombic-dodecahedron faces, its outline is hexagonal.) the several layers of particles parallel to any one of these faces are continuous over the other faces, although the particles themselves are ranged along lines of different directions. hundreds of different planes of particles can, in fact, be traced out in such a structure; and these structure planes are parallel to possible external faces on the crystal. a close relation exists between the millerian indices of these faces and the number of particles along certain lines in the correspond- ing planes. the dotted lines on the front cube face in fig. 2 repre- sent the intersections or traces of such planes with the indices: (r41),, gat), (11) eta (991); (4an)ete.s gat), (431); eles respectively for the lines from right to left. the seven planes of which the indices have just been given necessitate by symmetri- cal repetition the presence of 93 other structure planes, or, in all, 200 external crystal faces. a study of fig. 2 shows that the spacing between the particles is not the same on each of the faces (allowance being made for forcshortening in the drawing; only on the front cube face are the fic. 3.—reflection of x-rays by planes of particles. particles represented at their true distance apart). on the cube faces the distances cach way are, of course, a. on the faces of the rhombic-dodecahedron they are spaced at distance a in one di- rection, but along the second dircction at right angles at distance v¥2a. on the octahedral face there is, instead of a rectangular grouping, a triangular and hexagonal pattern with the particles spaced at distances ¥ 2a in three directions. therefore the num- ber of particles on each of the faces is not the same for equal areas. the network of particles ts closer on the cube face than on the rhombic-dodecahedron, and more open on the octahedron. this “ reticular density ”’ of the different faces is important and is closely related to the cleavage of crystals. minerals with cubic cleavage (e.g., rock-salt and galena) would be expected to be of this structure. in addition to the spacing of the particles in the planes, there are also to be considered the distances between the planes them- selves. this can be represented by means of vertical sections through the structure perpendicular to the respective planes. the spaces between the cube planes is a, and the particles are also spaced at distance a; the pattern being, in fact, that on a cube face perpendicular to the first. the distance between the rhombic- dodecahedron planes is given by half the diagonal of the cube face, namely, a/¥2. here, however, the section- rock salt, or plane intersects lines of particles only (pbs). in alternate rhombic-dodecahedron planes. the distance between octahedron planes is given by one-third the diagonal of the cube, namely, a/v 3; and the par- ticles are at distances ¥6a apart along the traces of the octahe- fic. 4.—structure of calena crystallography dron planes, though only at distances a or +¥ 2a across these planes. : there are two other types of cubic lattice. one of these has an additional point at the centre of each cube (this may be called the centred cubic lattice), and another has additional points at the centre of cach face, giving the face-centred cubic lattice {represented by the white spots on the larger cube in fig. 4). the different relations afforded by these types need not be discussed here. but in the centred cubic lattice the greatest reticular den- sity is in the rhombic-dodecahedron planes, whilst in the face- centred cubic lattice the particles are most closely packed in the octahedron planes. these would be expected to correspond to cubic crystals showing rhombic-dodecahedral and octahedral cleavage (e.g., zinc blende and fluorspar) respectively. types of lattices other than the cubic are deduced by varying the distances of the particles along the different axes and by _ varying the angles between these axes, in a manner similar to that in which the six crystal-systems are deduced. in fact, the elements of the elementary cells of the lattice, namely, the ratios of their lengths and the inclination of their edges, are identical (except in certain cases) with the parameters a:b:c: and the axial angles a, b and y deduced from the external crystal faces. vhe “ particles ” referred to above may be crystal molecules, chemical molecules, or even atoms. ‘they are represented in the diagrams as spots without committing ourselves as to their shape or size (in relation to their distance apart). some authors represent them as spheres in contact with one another, regarding these as the spheres of influence of each atom. if the spheres are of equal size, the number of points of contact and the closeness of the packing will vary with the type of lattice. or again, we may regard the particles (all of the same size) as completely filling space. in this case the particles in the simple cubic lattice will be cubes, each in contact with six other cubes; in the centred cubic lattice they are cubo-octahedra with 14 surfaces of contact; and in the face-centred cubic lattice they are rhombic-dodecahedra with 12 surfaces of contact. vhe above outline of the geometrical structure of crystals has been necessary for the purpose of introducing the new x-ray methods of investigating the internal structure of crystals. x-rays or rentgen rays are propagated as waves in the same mannet as rays of ordinary light, but are of much smaller wave- length. the very fine rulings of parallel lines (about 7,000 to a em.) of diffraction gratings being of a magnitude (1074 cm.) com- parable with the wave-lengths of light, they produce well-known diffraction effects. it would be impossible to produce mechani- cally a grating which would be fine enough to diffract the much shorter x-rays. but it occurred to dr. max laue, of ziirich, that the reticular structure of crystals would supply the necessary grating, since the distances between the atoms in the space- lattices are of the order ro-?tcm. in 1912 this idea was put to the test, with very surprising results. plates cut from crystals parallel to certain faces were placed perpendicularly in the path of a th'n pencil of x-rays, and beyond a photographic plate was exposed. the resulting photograph (known as a laue photograph or radiogram, rontgenogram or rontgen pattern, or spot photo- graph) shows a larger central spot representing the direct rays, whilst surrounding it is a symmetrical pattern of smaller spots. the spots may also be shown directly by projection on a screen of fluorescent material. his pattern shows the same degree of symmetry as that on the crystal face. thus a plate from a hexag- onal crystal of beryl cut parallel to the basal plane (4.e., per- pendicular to the principal axis) shows a six-fold arrangement of spots symmetrical about six radial lines at 30°; whilst when the plate is cut parallel to a prism face of the same crystal, the spots are symmetrical about two lines at right angles. the results obtained with these laue photographs were at first explained as due to diffraction, but the problem is much more complex than diffraction by a single system of parallel lines in one plane, since we are here dealing with a lattice in three dimen- sions in which there are many series of lines in many planes. as explained by sir william bragg and his son, prof. w. l. bragg, in their book, x-rays and crystal structure, 4th ed. (1924), it is crystallography due to the amplification of waves reflected from successive layers of atoms within the crystal. in fig. 3 a beam of x-rays ab, a’ b’, a” b”, all of the same wave-length a, strikes at a glancing angle @ the planes of particles, the distances between which are d. they are reflected by successive planes as a single ray bc. produce a’b’ to d (then bd is perpendicular to the planes) and draw bn perpendicular to a’d. then, since b’b=b’d and ab=a’'n, the length of path of the ray a’b’c is greater than that of the ray abc by the distance nd=2d sin #. similarly, a" b”c is longer than a’ b’'c by the same amount. if, now, this distance is equal to the wave-length of the rays, if \=2d sin @, 767 reflections received on a photographic film. the tiny crystal fragments are in all manner of orientations; and further to ensure all possible orientations in the aggregate, the tube containing the small amount of powder is rotated during the exposure. for struc- tural planes with the spacing d there are bound to be some of the particles in the position shown in fig. 3 in which the equation a= 2d sin @ is satisfied; but these will be lying in all azimuths, i.e., sloping away in all directions at the angle @ from the axis of the rays. the reflected rays will consequently lie on the surface of a cone, the angle of which is 48; and, instead of a single spot, a continuous series of spots forming a circle will appear in the fic. §.—laue x-ray photograph through the basal plane of penninite. the rays reflected by successive layers of particles will be vibrating in the same phase and their amplitudes will be added together. if the glancing angle @ be varied but slightly, the re- flections from the millions of layers will vary in phase and they will mutually interfere. but at certain other glancing angles 02, 4s, when 2\= 2d sin @2 or 3x\= 2d sin 63, there will again be an accu- mulative effect, giving reflections of the second and third orders. in the bragg apparatus, called an x-ray spectrometer, homoge- neous (‘ monochromatic ’’) rays from an x-ray tube emerge through a narrow slit in a leaden screen and strike at a glancing angle the crystal plate mounted on a goniometer. the reilected beam enters an ionisation chamber containing sulphur dioxkle or methyl bromide and connected with an electroscope. the crystal is slowly turned on the goniometer until a maximum ef- fect is noted in the electroscope, when theangle is read. plotting the readings of the electroscope against those of the goniometer, a curve (x-ray “‘ spectrum ’’) is obtained which shows a series of sharply defined maxima or peaks corresponding to reflections of the first, second and other orders. knowing the wave-length of the rays, the distance between the planes of particles can then be calculated from the above fundamental equation; or, alter- natively, knowing the spacing of the planes, the wave-length of the rays can be determined. asanexample, rays from a palladium anticathode (“ palladium rays ”’) were strongly reflected from the cube face of rock-salt when the angle @ was 5-9°, 11°85° and 18:15°. taking the spacing d between the cube planesof rock- salt as 2-81 x10-* cm., the wave-length ais found to be 22-81 10-8 sin §-9°=0-578x107-§ cm., or 2a=2x2-81x10-* sin tr85 = 14154 10>> cm, a third method of investigation was devised by p. debye and p. scherrer in germany in 1916, and independently by a. w. hull in the united states in 1917. here a beam of homogeneous (‘“‘ monochromatic’) x-rays of known wave-length is trans- mitted through the finely powdered crystalline material, and the pia, 6.—stereogram of laue photograph of anhydrite on the face (o10). photograph. similarly, in other fragments the same set of planes with spacing d may be inclined at angle @ giving a second order reflection as required by the equation 2a= 2d sin @, and produc- ing a wider-angled cone concentric with the first. further, other structural planes with spacing d, and inclined at other values of @ will be provided by other fragments, giving still other conical reflections. since, however, the experiment 1s performed with rays of one wave-length, only certain values of d will satisfy the equation, so that the number of reflections is really limited. since only the angles of divergence of the concentric conical sheaths are to be measured, only a narrow strip through the centre needs be photographed. ‘this strip is made semicircular, in order to embrace a wide field of reflected cones. knowing @ and x, the equation gives, as in the bragg method, the spacing ¢ between the structural planes of the crystal. although the debye-scherrer method may be regarded as a modification of the laue method, yet the results it gives are the same as those given by the bragg method, namely, the spacing between the structural planes of the crystal. the laue method gives other supplementary information, but ideas of structure are built up mainly on the spacing between the planes of particles. a large amount of experimental work on crystals of different sub- stances has been done in this direction, and deductions have been drawn as to their probable atomic arrangement. in this place only one or two examples can be briefly considered. rock-salt (sodium chloride) crystallises as cubes and possesses a perfect cleavage parallel to the faces of the cube. plates cut parallel to the faces of the cube (100), the rhombic-dodecahedron {110), and the octahedron (111), respectively, give by the bragg method values for the spacing between the planes of particles in the ratio of 1:1/¥2:1/¥3. these ratios are the same as those mentioned above for the simple cubic space-lattice (figs. r and 2), and the conclusion may be drawn that this represents the struc- ture of rock-salt. the two kinds of atoms, sodium and chlorine, 768 may be placed alternately along the three directions, as shown in fig. 4. asso represented the structure may also be regarded as an interpenetration of two space-lattices of the face-centred cubic type, with the sodium atoms on one lattice and the chlorine atoms on the other. one lattice can be brought into the position occupied by the other by a parallel shift along a cube edge through the distance between two consecutive planes. the actual dis- tance between the cube planes, and consequently also between the atomic centres, has been determined to be 2-81 x 107% cm., or rather more than a hundred-millionth of an inch. in the draw- ings, the scale of the lattice is enormously enlarged, and only an infinitesimal portion of the crystal is represented. some idea of this may be conveyed by saying that if we took a cubic inch of rock-salt and represented the whole of the structure on the same scale as in fig. 4, the drawing would be rather more than 1,000 m. across. the same structure is also shown by galena (lead sulphide, pbs), the crystals of which also possess a perfect cubic cleavage; the two kinds of atoms shown in fig. 4 here represent lead and sulphur. examples of crystals with the structure of the centred cubic lattice are those of the metals iron, sodium, tungsten. the face- centred cubic lattice is represented by crystals of the metals copper, silver, gold, platinum. a special type of cubic lattice, known as the “ diamond lattice,’’ consists of another kind of interpenetration of two face-centred lattices. particles belonging to one lattice are placed each at a centre of alternate sub-cubes in the other lattice, and a tetrahedral arrangement so results. examples of this are diamond and zinc blende (zns). crystals of various substances are extensively used as radio- detectors in wireless telephony, but no satisfactory explanation of their action has yet been given. an essential character of crystals is a variation of many of their physical properties with the direction within the crystal—in other words, such properties are vectorial. bratiocrappiny.—a. e. h. tutton, crystallography and practical crystal measurement (2nd ed., 1922), and the natural history of crystals (1924). in addition to bragg, x-rays and crystal structure quoted above, see: p. p. ewald, kristalle und rentgenstrahlen (1923); c. mauguin, la structure des cristaux determines au moyen des rayons x (1924); r. w. g. wyckoff, the structure of crystals (1924); and the analytical expression of the results of the theory of space- groups (1922). p. niggli, geometrische krystallographie des diskon- tinuums (1918). elementary text-books are: t. l. walker, crystal- lography, an outline of the geometrical properties of crystals (1914); j. w. evans and g. m. davies, elementary crystallography (1924); p. groth, elemente der physikalischen und chemischen krystallographie (munich, 1921); n. h. winchell and a. n. winchell, elements of optical mineralogy, part i (1922). a collection of thousands of drawings of crystals with critical lists of forms is given by v. gold- schmidt, atlas der kristallformen (nine 4to vol., heidelberg, 1913-23). new crystal-forms together with other crystallographic constants are listed in the international tubles annuelles de constantes et donnees numeriques (5 vol., paris, 1912, etc.). cuba (see 7.594), a republic in the west indies and a member of the league of nations. area 44,164 sq. m. (including the isle of pines). since 1909, when for the second time the management of cuban aflairs was turned back by the united states to the cuban govt., there has been a remarkable growth in the wealth and prosperity of the island. population increased from 2,048,980 in 1907 to 2,889,004 in r919. no fresh census was taken between 1919 and 1925, but estimates gave cuba about 3,330,000 in the latter year, or over 60% more than in 1907. this increase was largely due to the rapidly advancing number of immigrants. while many represent a mere floating population who return to their own country within the year, a number remain per- manently in the island. according to the census of 1919 there were only 65 persons per sq. m., in a country whose habitable area represents an unusually large proportion of the whole. the pros- perity of the island is due mainly to its natural resources, but in part to the virtual underwriting of the republic by the united states, which has a right under the platt amendment to inter- vene in cuba to maintain order, and also has some control over cuban finances through the requirement that cuba may con- tract no public debt beyond the capacity of the republic to repay, which virtually involves the consent of the united states. cuba i. political history jose miguel gemez, who had been the candidate of the liberals, became president on jan. 28 1909, and remained in office until may 20 1913. his term was marked by a return to the traditional political evils of the former spanish colony; but though the government was corrupt the country prospered and public works were developed. among a number of political disturbances the race war of 1912 was the most serious. this was a negro uprising in oriente which, however, was quickly suppressed; a body of u.s. marines was landed for the pro- tection of foreign nationals and their property. owing to friction within the liberal party the conservative candidate, gen. mario g. menocal, was elected in 1912 and took office in 1913. charges of maladministration and dictatorial methods were persistently brought against menocal’s govt., which was unable, furthermore, to show much in the way of positive achievement. nevertheless, the first three vears of his term were moderately successful. menocal was again a candidate in 1916, and won the election by the employment of violence and other improper meth- ods. in consequence there was a serious civil war under the leadership of gemez in feb. 1917, but menocal was able to defeat his opponents and entered upon his second term. mean- while, cuba had followed the lead of the united states and declared war on germany on april 7 1917. little opportunity was given to cuba to take an active part in the struggle, but great help was rendered through stimulating the production of sugar for sale to the allies. in anticipation of the elections of 1920 gen. enoch h. crowder of the u.s. army was invited to cuba in 1919 to draw up an election law. this he did, but the law was flagrantly disregarded in the ensuing elections. alfredo zayas, who had been the liberal candidate in 1916, was now backed by menocal in a conservative-popular alliance against gemez, who was nominated by the liberals. zayas was success- ful but gemez raised a protest, and new partial elections were called for at the suggestion of gen. crowder, who had been again sent to cuba as the personal representative of the president of the united states. gemez withdrew before they could be com- pleted, claiming unfair methods of the government, and zayas had an easy victory. meanwhile, cuba had enjoyed phenomenal prosperity in the “ dance of the millions ” of ror9, as it was called, but this was followed by a severe financial crisis in the depression of 1920-1. despite the declaration of a moratorium in the payment of debts, many banks and other business concerns were forced into bank- ruptcy. because of the financial difficulties of the republic the government of president zayas, who went into office on may 20 1921, was at first amenable to suggestions for reform made by the u.s. government. a loan of $50,000,000 was approved by the united states and successfully floated in jan. 1923, and finan- cial conditions rapidly improved. the cuban war loan of $1o,- 000,000 was liquidated and the year 1922-3 closed with a sur- plus. but with the return of prosperity in 1923 president zayas broke away from his advisers, and his politica! impropricties led to the formation of the veterans’ and patriots’ assn., whose re- form movement was badly mismanaged and failed in the abor- tive revolution of april-may 1924. zayas would not indulge in the violence of his predecessor, however, and when he was defeated by menocal, for the conservative nomination, made a pact with gen. gerardo machado, the liberal candidate, to assist him against menocal in the presidential election of 1924. machado was victorious and assumed office on may 20 1925. during the zayas administration the ownership of the isle of pines was deciced in favour of cuba. | education.—education called for greatly increased expendi- ture after 1909, but without commensurate beneficial results, because of political factors involved. it was stated that in 1924 63°4 of the population could neither read nor write. the uni- versity of havana, with over 4,000 pupils, is tending gradually to model its curriculum on the pattern of universities in eu- rope and the united states. the university was thoroughly reorganised in 1923. cubism—culture contact, psychology of ii. financial and economic history under a law of nov. 7 ro1r4, a cuban coinage system similar to that of the united states was introduced. american money is also legal tender and is in general use. the following table shows the national revenue and expenditure for 1913-4 and 1919- 20 to 1925-6:— revenue expenditure 1913-4 . $37,940,200 $33,974.147 t919—-20 . 91,308,314 91,726,152 [920-1 64,446,000 62,730,744 1922-3 53,628,800 54,552,102 1923-4 73,134,313 57,758,734 1924-5 68,500,000 61,672,169 1925-6 84,791,650 64,780,250 no detailed figures are available for 1921-2. the period 1923-6 showed a considerable surplus, which was applied to the reduc- tion of the public debt. in r925 cuba had a foreign debt of about $87,000,c00 and a domestic debt just under $12,000,000. in addition, the country has a floating debt of something like $14,000,000. production and industry.—sugar its the basis of cuba’s wealth. the crop, which in tg910-1 amounted to 1,379,609 tons, was 5,151,486 tons in 1924-5, or nearly a fourth of the world’s total production. between 1909 and 1925 the crop generally increased each year, but there were wide fluctuations in price. sugar rose from a normal level of around 3 cents a pound, to as much as 3% cents during the world war, and then to an inflated level of 225 cents in 1920. in that same year the market broke, and the price fell to 3% cents, rising again in 1923 to an average level of 4-9 cents. heavy production in different parts of the world caused a fall in price to less than 3 cents in 1925. many cuban sugar estates are under control of american companies and in 1924 some 60% of the industry was in american hands: alto- gether the value of american investments in cuban sugar op- proaches a thousand million dollars. the united states takes about 85% of the entire cuban crop. cuban tobacco products are among the most highly regarded in the world, but the industry, though second in importance in the island, does not compare with that of sugar. the crop hada value of $82,280,686 in t924. all other cuban industries are insignificant by comparison with sugar and tobacco. jn the war and post-war periods the market for molasses, a by-product of sugar, assumed considerable proportions. the climate and soil are favourable to fruit culture, notably citrus fruits, bananas, pineapples and cocoanuts, but the full possibilities of the industry have not been realised. the grazing industry has attained to some prominence, particularly in the province of camagiiey, where there were about 4,500,000 cattle in 1925. there are iron, manganese, copper and asphalt mines in the island, especially in oriente; signs of oil have been reported over large areas. the henequen industry of matanzas and sponge industry of bataban6e are locally important. the greater part of the capital in cuban industries as a whole comes from the united states, which has a total investment of nearly $1,500,000,0c00. this compares with an investment of $80,000,000 in 1901. while most of the ameri- can money is in sugar, there are also large sums in tobacco, mining, fruit, railways, street-car companies, docks, electric light and power companies, telephone companies, banks, hotels, steamship lines and cuban bonds. commerce.—cuba exports all but a little of what it produces, and imports nearly everything it consumes, even including food products, which constitute some 35 to 40% of the total. sugar makes up 85°% or more of the exports in value, with tobacco 8 or 10%. the increase in the value of cuban trade has been little less than phenomenal. in the period 1900-4 cuba had an average annual volume of trade of about $136,000,000. this had reached a total of slightly more than $300,000,000 in 1914 and approximately $725,000,000 in 1924, the highest figure up to that time in cuban history, except for the inflation period of 1919-20. in 1920 the volume of trade with the united states alone was $1,125,000,000, but value in dollars was hardly a correct index then. cuban products enjoy a preferential tariff of 20% in the united states, while those from the united states get a con- 769 cession of from 20°% to 40% in cuba. this is one of the reason for the dominant position of the united states in cuban trade during the period of 1900-4 the average annual value of u.s trade was only some $101,000,000. disregarding the abnormal figures for 1920, american commerce with cuba had reached a total of $553.510,261 in 1924, or about 76% of the total. cuban exports in 1924 were valued at $434,069,c00 and imports at $290,525,585. during the period 1910-25 the balance of trade in favour of cuba greatly increased. communications —there are two principal railway systems in cuba, which also control several lesser lines. the united railways of havana is an english company, which is the dom- inant factor in the west, while the cuba railroad, an american company, is in control in the east. the latter has greatly ex- tended its sphere through acquiring virtual control of the cuba northern railroad co. in 1924. while the island is, on the whole, well served by railways, with some 3,250 m. in operation in 1925, the same cannot he said for the roads. large sums were expended between rgog and 1924 in roadbuilding, but with little benefit lo the republic; at the beginning of 1925 the roads were gencrally in a bad state of repair. direct steamship connec- tion exists with numerous european and american ports, with frequent sailings, and there is a train service to the united states vig a ferry from havana to key west. air services for both passengers and mails are maintained between havana and the united states. bibliography.—r. p. porter, industrial cuba (1919); w. b. parker, cubans of to-day (1919); g. c. musgrave, cuba: the land of opportunity (1919); ll. valdes roig, fi comercio exterior de cuba (1920); c. m. trelles, bzblioteca geogrdfica cubana (1920); c.m. trelles, biblioteca historica cubana, 2 vol. (1922-4). see also anuario estadistica de la repiblica de cuba (1974, ete.); british department of overseas trade reports on the economic conditions in cuba (1923 and 1925). (c, e. cu.) cubism: sce painting. culture: see anturopology. culture contact, psychology of (for psycuo ocy, see 22.547).—dresent-day psychology is less concerned with describing how and what a man thinks, feels and acts than with trying to understand the causes of his conduct. every normal man’s activities are to a large extent socially determined, and, whether he ts aware of it or not, are directed towards the perpetu- ation and development of the complicated systems of culture characteristic of social groups. consequently, the psychologist is as interested in culture problems as the ethnologist and the sociologist, and he has his own especial contributions to make towards the study of the growth, distribution, maintenance, and transformation of culture patterns. social instituttons.—no social group has ever been known which does not possess distinctive customs and institutions. these, and the tendencies which cluster about them, are, in fact, the characteristics that we use whenever we wish to give a psychological definition of any particular group. such customs and institutions are constantly being elaborated or simplified; old features are built up into new patterns, or pass away. and the changes are never haphazard. they proceed according to certain principles. the discovery of these principles lays bare the secrets of the growth of culture, and for this and the formula- tion of the principles a psychological method of approach must be adopted. the main, if not the only, gencral condition of mental and social development is that the individual or the group should come into contact with other individuals or other groups. the resulting clash of feelings, actions, ideas, customs and _ institu- tions is the great stimulus to change. modes of contact.—but this consideration obviously does not carry us very far. social contact may take several different forms. first, a number of people mav migrate as a whole group, and, carrying with them all the features of their special culture, may find a new temporary or permanent abode. the customs and institutions of these immigrants will then mingle with, or per- haps even replace, those of the people to whom they have 770 come. the complexity of many of the characteristics of aus- tralian and melanesian culture has been attributed mainly to a series of group contacts of this kind, and illustrations of the same mechanism of diffusion abound in almost every part of the world. second, an individual may break away from his original home, and, attaching himself to an alien group, assimilate cer- tain features of their peculiar culture. later, returning home, he introduces the borrowed elements into his old group, and there, under certain circumstances, they will root and thrive. this is a mode of diffusion particularly characteristic of modern society, and it is constantly illustrated in changes of culture which are open to daily observation. contact and borrowing.—the two cases must be distinguished. the first is “ diffusion by contact,” the second “ diffusion by borrowing.’’ both occur at all stages of social development, but the second probably plays a larger and larger part as civilisation advances. in a third, intermediate, form of diffusion, groups living in close proximity and friendly relationship constantly intermix, with much resulting interchange of cultural elements. it is clear then that there is no safe argument immediately from similarities of culture to “ diffusion by contact.”?” we must study carefully the mechanisms by which ‘‘ contact ” or ‘‘ borrowing ” may be set to work. mechanisms.—these mechanisms can, no doubt, be partially described in terms of the sphere of culture affected, whether material or ceremonial: for instance, of external environmental conditions; of the relative numbers of the groups involved, and in other more or less purely objective ways. but at the basis of these are the attitudes and tendencies of the individuals and groups in question, and in these and their consequences psy- chology takes an especial intcrest. first consider the case of “ diffusion by contact.’”? the con- sequences which ensue when two groups meet, each with its own relatively complete and characteristic institutions, customs and beliefs, depend directly upon the dominant social relationship tendencies which are brought into play. among man’s instinctive endowment are certain tendencies which are peculiarly social. the three most important of these are: assertiveness, sub- missiveness and a characteristic tendency best termed the tendency towards “ primitive comradeship ”’ which leads to a social relationship with much interchange but no assumption of superiority or of inferiority. these tendencies come to dominate a man’s attitude towards his fellows, and get so built up into group life that they prominently determine a group’s reactions to other groups. | survival and instability —when two groups come into contact for any length of time, the one being markedly assertive, and the other markedly submissive, the culture of the first seems completely to displace that of the second. but frequently there is only a surface victory. the customs of the submissive group are merely driven underground. they persist in secret and burst out again unexpectedly in timesof social unrest. the com- munity produced is socially unstable, and liable to profound regressions. if, however, the dominance of one group is less pronounced, and the submissiveness of the other less complete, many of the customs of the indigenous and of the incoming people persist for a long time side by side. an apparently bewildering com- plexity of cultures is produced. but in the end genuinely new and stable social patterns are constructed. finally, where “ primitive comradeship ”’ is the dominant social tendency, a true blending of cultures is secured, and a cultural structure is evolved which contains elements from both sides relatively unchanged. control of existing culture-—by whatsoever route the stimulus to new cultural developments reaches a group—whether by contact or by borrowing—all imported material has to be fitted into some already existing cultural pattern, otherwise its position in the new group remains exceedingly unstable. for the deep- seated human tendency towards conservation 1s immensely strengthened by social grouping. conservation is, however, always subject to control and direction by other tendencies, and is, consequently, selective in its operation. most commonly of culture contact, psychology of all it is controlled by impulses that immediately serve practical needs. thus a group may cling very tenaciously to a food-seek- ing ritual, but be comparatively ready to change its food-secking . instruments for others which are in practice obviously more efficient. the operation of this principle of selective conservation means that even when systems of culture move as a whole they are practically never accepted as a whole. they must submit to the inertia of the culture patterns of their new homes. in the end it will appear as if they moved, not as a complex unity, but as elements ‘“‘ lifted ” from a whole. the elements that persist are those which have direct practical utility, those which present obvious affinities to an already existing culture, and very often those which appear odd, disconnected, incidental and of small importance. to understand why, in a given social group, certain features of culture are jealously guarded from change, while others can be fairly easily displaced, a thoroughgoing intensive study is necessary, not merely of what reaction tendencies are operating in a group, but especially of how these tendencies are arranged. formation of new patterns.—because conservation is selec- tive, any change successfully introduced into a community from without tends to produce eventually a new social pattern. but in addition to this, the normal individual and the normal group both show a genuinely constructive capacity. no idea received into a mental life, no custom accepted within a group, remains isolated. it has to be built into a structure with other ideas and with other customs, and the result is often peculiar to the individual or group concerned. no social psychologist has yet carried out a radical analysis of what is involved in social con- structiveness. the problem is one for the future, but undoubtedly in this sphere particularly the initiative of prominent indivi- duals within the group plays a most important part. definite foresight and articulated purpose have a great deal less to do with the matter than has frequently been supposed. the individual.—when considering ‘‘ borrowing”’ we picture a migrant individual who leaves his group and settles for a while in an alien social environment. some features of his new setting will attract his attention and inspire his envy; others he will notice and then ignore; yet others he will fail altogether to detect. from the psychological point of view there are three groups of conditions which are particularly important in deter- mining these responses. first, there are the group of instinctive tendencies which this individual possesses in common with all other human beings, which have their unique arrangement in every person. second, there are that endowment of specific tendencies and that development of ‘‘ interests’ which mark off the migrant individual in question from all other persons. third, there are the social traditions, customs and institutions of his own people, which, in fact, though they belong to the wanderer’s native group, yet affect his conduct in the most direct manner. these all, coming into operation together, deter- mine what he will “ borrow.” eventually the borrower returns to his own group. he may, of course, make no attempt whatever to introduce the bor- rowed material into his native society. he may continue to practise the alien customs, but then, as a rule, they will not make much impression, and will speedily disappear. he may, however, have the temperament of a propagandist, or be what is called ‘ public-spirited,”’ and if this is the case he will seek con- verts to the new ways. innovations —here again the fundamental social relationship tendencies are important. there is a “primitive comradeship” type of innovator. such a person at once, though unwittingly, modifies the newly accepted cultural matcrial in the direction of the traditional customs and institutions of his own group. he has a distinctive mode of propaganda, in the main persuasive, and working along the established lines of social organisation of his society. but in spite of this, as soon as his innovations at- tract notice they are almost invariably met with hostility from one party and with acceptance from another party. at once the borrower becomes a centre of social attention, and this reacts strongly upon his whole attitude and practice. he is now apt cum mins—cduril to emphasise the difference between the new proposals and the old culture, and to join reformers who are more radical than himself. there frequently grows up a definite cleavage between the new and the old. despite everything, however, the powerful conservative tendencies of the group will gradually give to the innovation something of the shape of the long-standing culture of the society concerned. special groups.—yrobably no new custom, .however it may be introduced, makes social headway without the formation of a special group which takes the custom as its rallying-point. any such group is apt to be rendered conspicuous in the eyes of the other members of the community. thereupon it is subjected to precisely the same kind of socially initiated influences that, as we have seen, affect the individual borrower. such a group tends to become relatively assertive, or dominant, in the society to which it belongs, and endcavours to increase its prestige. then the customs and institutions which are the peculiar stamp of the group in question invariably undergo elaboration. at the same time the group may jealously protect itself from new-comers, guarding its secrets with care, and making entrance into its ranks difficult and perhaps dangerous. his is the typical condition for the growth of elaborate social culture. simplification. elaboration of culture, however, may carry the elements of its own decay. if it proceeds to extremes the special groups concerned are apt to become cut off from contact with the bulk of the people. deterioration and simplification of culture invariably follow. this may be called “ simplification by isolation.” on the other hand, a group formed about new customs may open its ranks widely, so that almost anybody who wishes can learn its secrets. this also leads to a deterioration of culture, and may be called “ simplification by spreading.”’ simplification by isolation is a common fate of systems of ceremonial culture; simplification by spreading is more frequently found with mate- rial culture. it is an interesting fact that, as in the mental life of the individual, so in the social life of the group, a certain amount of conflict is the most general condition of constructive effort. the special devices by means of which elaboration and sim- plification are secured are also, to a large extent, psychologically determined. for example, ceremonial practices, details and products of material art, artistic designs, songs, linguistic pecu- liarities and even details of social organisation travel more readily than the interpretations xttached to them. yet if re- tained in a new environment they must be interpreted. the interpretation given is often the work of some prominent individual. details come from without, interpretations grow up from within a group, and a common interpretation of differing materials often aids greatly the construction of new cultural patterns. reduplication and genuine conscious invention have their predisposing conditions, and their special functions in elaboration. simplification may result from the fact that certain ideas, belicfs and practices may grow so strong in a community that they tend to absorb all others. the same general effect may follow unwitting omissions in copying or in imitation. or apparent simplification may be caused by the repression of socially undesirable elements of a custom or institution through a contlict of groups or of social tendencies. only the intensive study of particular groups and particular cultural problems can show exactly what has happened in any given case, and so dis- close the principles which come into operation. such intensive study contemporary psychology is beginning to undertake. a little has been accomplished, more remains to be done. no doubt the conclusions which have been reached so far will in the near future be corrected and supplemented. brstiograpiuy.—the field of study dealt with in this article has been as yet but meagrcly explored. a great amount of important material is to be found in monographs and special studies of par- ticular groups. these are very numerous, and no attempt can be made to indicate here important works belonging to this class. for more or less general discussions see f. m. davenport, primitive traits in religious revivals (1905); w. h. r. rivers, ainskip and social organization (1914); f. j. teggart, prolegomena to llistory 771 (1916) and the processes of history (1918); r. r. marett, psychology and folk-lore (1920); f. c. bartlett, psychology and primitive cul- ture (cambridge, 1923); l. levy-bruhl, primitive mentality (1923); m. t. price, christian missions and oriental civilisations, a study in culture contact (shanghai, 1924); f. j. teggart, theory of [istory (1925). (fece by) cummins, albert baird (1850- ), american politician, was born at carmichaels, pa., feb. 15 1850. he was educated at waynesburg (ta.) college, studied surveying, and was at first engaged in railway work. he then took up law, was admitted to the bar of illinois in 1875, and for three years practised in chi- cago. in 1878 he went to des moines and ten years later was a member of the iowa house of representatives. iie was chair- man of the republican state committee (1892-6), candidate for the united states senate in 1894 and 1900, member of the re- publican national committee (1896-1900) and a delegate to the republican national convention on four occasions. he was elected governor of iowa in 10902 and re-elected for two suc- ceeding terms. in 1908 he was elected to the united states senate to fill the unexpired term of senator allison, and was re-elected in 1909, 1915 and 1921. ile opposed the nomination of mr. taft in 1912, but dic not leave his party. he was specially identified with measures concerning trusts and railways, and took a lead- ing part in drafting the esch-cummins act, under which the govt. in 1920 handed back to private control the railways of the united states. cunliffe-lister, sir philip (1884- ), british politi- cian, was born may 1 1884 at ayton, yorkshire. the youngest son of lieut.-col. yarburgh g. lloyd greame, he assumed by royal warrant the name of cunliffe-lister in dec. 1924. he was educated at winchester and university college, oxford, and was called to the bar in 1908. during the world war he served with the king’s royal rifle corps, attaining the rank of major. elected conservative member for hendon in 1gr8, he quickly made his mark in parliament as a speaker on commercial subjects. he was chairman of the labour committee of the war cabinct, and served on other important government committees. he was parliamentary secretary to the board of trade and of the qver- seas trade department in the lloyd george coalition govern- ment till his appointment by mr. bonar law as president of the board of trade in nov. 1922. he held the same office in both mr. baldwin’s administrations, and presided at the imperial economic conference held in london in 1923, when he advocated the extension of imperial preference. he carried through parlia- ment measures for safeguarding particular british industries through protective tariffs. cunningham, william (18409-1019), british economist (see 7.633), died at cambridge, england, june 10 1919. cunninghame graham, robert bontine (1852- ), british writer, eldest son of william cunninghame graham of ardoch and gartmore, was educated at harrow. he spent much of his youth cattle-farming in the argentine, and travelled widely in paraguay, mexico, spain and morocco. a spanish grandmother made the spanish language and national tem- perament singularly congenial, and his writings are throughout coloured by these early experiences. cunninghame graham sat as m.p. for north lanarkshire from 1886-92, and took an active part in labour politics, being closely associated with john burns and keir hardie in their early days. characteristic of his varied writings, essays, travel notes, biog- raphy and stories are these: mogreb-el-acksa (1898); a vanished dircadia (1901); success (1902); hernanda de soto (1903); faith (1909); a brasilian afystic, a life of antonio conselheiro (1920); and a biography of his ancestor, doughty deeds of robert graham, 1735-97 (1925). see also ].. chaundy, a bibliography of the first itditions of the works of robert bontine cunninghame graham, curie, marie (1867- ), french scientist, the daughter of professor sklodowski, a pole, was born in warsaw nov. 7 1867 and studied in paris, taking a science degree at the univer- sity there. in 1895 she married dr. pierre curie (see 7.644), the french physicist; and after working for several years at the ecole de physique et de chimie in paris, she carried out highly important experiments on the radio-activity of uranium ig. currency compounds, a phenomenon discovered by henri becquerel in i896. this research work led up to the epoch-making discoveries of polonium and radium. after years of arduous work (carried out in an abandoned shed with the most primitive equipment) s[adame curie succeeded in isolating pure radium salts. the nobel prize was awarded to her in 1903, in company with dr. curie and becquerel; and in the same year she became a doctor of science. on the tragic death of her husband in 1906, she succeeded him as professor at the paris university and in 1911 was awarded the nobel chemistry prize for her work on radio-activity. the paris radium institute and the warsaw radio-activity lab- oratory owe much to madame curie. during the world war she organised a valuable radiological service in the hospitals and later directed the curie laboratory in paris. in 1921 president harding, on behalf of the women of the united states, presented her in person with a gramme of radium in recognition of her great services to science. see radio-activity; radium.