I.WTAKY [6, K)I<) 



NATURE 



39s 



So far the factor has experienced con- 

 siderable difficulty in carrying out lis programmi 

 ol work. In 1915-16 the machinery was not com- 

 plete in time for full working, and there was also 

 a difficulty in getting sufficient cane In 1910-17 the 

 sugar-cam- crop in the district was a failure, and onh 

 a small supply of inferior sugar-cane was available for 

 working 



The note, in addition to giving a rdsumi of the work 

 don.', describes the native methods of making "gur" 

 and sue. 11. and includes an illustrated description of 

 the plant in the experimental mill. 



The following figures quoted bj the authors illus- 

 irl) hew much remains to be done to put the 

 Indian sugar industry on a basis which will enable it 

 to compete with Java. The figures are maunds of 

 Sugar produced per acre :- Java (modern methods), 

 leilly district (modern methods), 64 ; Bareilly 

 district (native methods), 74. ■ In view of these figures 

 it is little wonder that, in spite of a 10 per cent, 

 import duty and the payment of freight, railway, 

 handling, warehousing, and other charges, Java can 

 -ell sugar in the interior of India against the locally 

 produced article. 



////•. FLORA OF MACEDONIA. 



THE Kew Bulletin (December, 1918) contains an 

 account of the flora of Macedonia by Mr. W. B. 

 Turrill, based on collections made by himself and a 

 few other men engaged with the British Salonika 

 forces. The collections were made mainly in the 

 Struma plain, on the " Lembert Hills," about 8 to 

 10 km. north of Salonika, and the Krusa Balkan, and 

 represent the flora of the hills (which nowhere reach 

 more than 1000 m.), the foothills, the nullahs, and 

 the plains. The most striking plant of the hill-slopes 

 i- the Kermes oak (Quercus cocci f era), a shrub from 

 2 ft. to 6 ft. in height, with very still, prickly leaves, 

 the host of the crimson-dye yielding "Kermes" insect, 

 which constitutes a distinct formation related to the 

 "maquis" of the Mediterranean area. The nullahs 

 are of two types : those worn out of the solid rocks 

 of the hills, and those cut out of the diluvium of 

 the plains by streams and storms. They have 

 generally very steep sides, which serve as a protec- 

 tion from the sun for at least part of the day, and, 

 as they retain considerable moisture, are able to 

 maintain a flourishing vegetation through the hot 

 summer. When water permanently runs through the 

 nullah a marsh flora may be found on the stream- 

 sides, including our British Lythrum salicaria, with 

 Cyperus longus, and species of Juncus, Carex, 

 Scirpus, Eleocharis, and others. Much of the ground 

 of the plains is, or has been, under cultivation, and 

 present time the weed flora is luxuriantly 

 ied; the Struma plain in spring was brilliant 

 with fields of scarlet poppies, pink Silenes, yellow 

 Hvpecoum, and a blue lupin. 



The parts traversed were generally poor in tree- 

 growth, and forestry is non-existent. The " Lembert 

 Hills " are bare except for the shrubby Quercus forma- 

 tion and low herbage. Inland, trees occur, but nearly 

 always singlv or in small groups, seldom worthy of 

 the name of woods. Quercus conferta is the com- 

 mon. -1 tree in manv districts, and also occurs as a 

 nullah shrub. In the Struma plain elm-trees reach 

 a good size, and isolated planes are well developed in 

 various localities. 



The climate is typically Mediterranean in the long, 

 hot, dry summer, but differs from the climates of 

 most Mediterranean countries in having colder and 

 wetter spells in winter. The autumn rains in October 

 revive the parched vegetation and cause a short period 



2568, VOL. I02] 



of flowering in autumn before the cold winds and 

 snow of winter. 



The author records 625 species and varieties of 

 flowering plants and ferns, representing probably 

 about a quarter of the vascular plants. The flora 'is 

 predominantly Mediterranean, and is most closely- 

 related to the Grecian flora; about one-sixth of the 

 species are common to Macedonia and Greece, but do 

 not extend northwards into Bulgaria. The northern 

 element is, however, distinctly marked, since thirty- 

 eight plants are recorded which occur in Macedonia 

 and Bulgaria, but not in Greece. 



One new species is described, a pink-flowered 

 Sili ne from the Struma plain. 



THE MATHEMATICAL ASSOCIATION. 

 ^PHE annual meeting of the Mathematical Associa- 

 -*■ tion was held in the London Day Training 

 College, Southampton Row, on January 1 and 2. At 

 the "Advanced Section" of the meeting Dr. S. 

 Brodetsky read a valuable paper on "The Graphical 

 Treatment of Differential Equations." He briefly 

 described the manner in which he was- led to take up 

 this subject by being confronted with "insoluble" 

 differential equations while researching on the stabilitv 

 of motion in connection with aeroplane theory. The 

 plan he devised was to sketch first of all on squared 

 paper the curves dyjdx = o and d 2 y/dx 2 = o, thereby 

 obtaining those regions in which the curves satisfying 

 <j>(x, y, dyjdx) = o have positive and negative curva- 

 ture. Thereafter, by solving directly for dy/dx in 

 terms of x\ and y, he is able to sketch the curves 

 of the system defined by the given differential equa- 

 tion <p(x, y, dy/dx) = o as a series of short arcs. 



At the " General Section " Dr. W. P. Milne dealt 

 with "Tin Work of the Mathematical Association in 

 Assisting the Application of Mathematics to Industrv." 

 He pointed out that up to now the Mathematical 

 Association had confined itself almost entirely to the 

 work done in the secondary schools, and he said that 

 in the work of industrial reconstruction the association 

 had a wide and clamant field of potential mathematical 

 activity in the deoartments of engineering, mining, 

 agriculture, commerce, etc. All these spheres of 

 labour are making a great and ever-increasing use 

 of mathematical processes, and it seemed fitting that 

 the association should lend a helping hand in drawing 

 up the appropriate mathematical syllabuses on the 

 most modern lines. It was also informally suggested 

 that, in addition to the London meeting at Christmas- 

 time, a peripatetic meeting should be held in the 

 summer-time at different places in the provinces, so 

 as to studv on the spot industrial mathematics in its 

 various forms. Upon a show of hands being taken, 

 it was found that the meeting cordially approved of 

 this informal suggestion. It was also announced that 

 the association had arranged for a series of reports 

 by expert committees on the mathematics of the 

 various pivotal industries, and that these would be 

 made public in due course. 



The presidential address by Prof. T. P. Nunn on 

 " Astronomv as a School Subject" was listened to with 

 the greatest attention and appreciation. Prof. Nunn 

 pointed out how desirable it was that modern educated 

 men should know something of the world in which 

 thev lived, and said that from time immemorial the 

 movements of the earth and the celestial bodies had 

 excited the interest and admiration of men. He ex- 

 hibited models of celestial cylinders, spheres, and 

 cub. s, all of which could be made with the simplest 

 apparatus, and from which most accurate results could 

 be obtained by schoolbovs themselves. Many school- 

 masters gave their exneriences of teaching astronomy, 



