GRAPHIC 



3648 



GRAPHOTYPE 



MONDAY TUFSDAY WEDNESBAY THURSDAY FRIDAY SATURDAY SUNDAY 



6 aJ n. Noon 6p.m Mid. 6am. Noon 6pm. Mid. 6am. Noon 6p.m. Mid. 6ajn Noon 6p.m. Mid. 6am. Noon 6pjn Mid. 6a.m. Noon Bp.m Mid. 6am Noon 6p.ru 



70' , ..............; ..MM.MI.MMMIMIMIMMN.IM , i j , . i . . 1 1 i . i 1 1 M i . i .. i i i i H i I TTTTTTTTTTn *>* 





60 



60' 



50' 



Graph, showing variation of temperature from hoar to hour during one week. The temperature is seen to be steadily fall- 

 ing from 63 F. to 45 F. See also text 



Another example of the use of 

 graphical methods is shown in 

 the chart giving the temperature 

 during one week. Horizontally, 

 at equal distances, are marked the 

 days of the week, while vertically 

 appear temperatures in degrees 

 Fahrenheit. The temperature 

 at noon on Monday is 64 F., 

 and a point is made on the chart 

 where the 64 line and the Monday 

 noon line meet. Similar points are 

 made for the temperatures for 

 every six hours during the week, 

 and these points are all joined, 

 either by straight lines or curved 

 lines, showing the gradual increase 

 or fall of temperature. This chart 

 tells its own story at once, that the 

 temperature on the whole during 

 the week has been steadily falling. 

 The line joining the various points 

 on such a graph, whether it is 

 straight or not, is called the curve 

 through the points. 



In mathematics, graphical 

 methods are very largely used for 

 the solution of algebraical and 

 other problems. In algebra one 

 function y is often expressed in 

 terms of another function x, so 

 that as x varies in value, so does y. 

 Now if along the two axes of re- 

 ference are measured distances x 

 and y, which correspond to one 

 another, a curve representing the 

 equation y=F (x) may be drawn. 

 By this method an approximate so- 

 lution may be obtained to any equa- 

 tion, however complicated, where 

 it is impossible to obtain a solution 

 by any other method. See Baro- 

 graph ; Coordinates ; Geometry. 



Graphic, THE. London weekly 

 illustrated newspaper. It was 

 started Dec. 4, 1869, by W. L. 

 Thomas, a feature being acceptance 

 of drawings whatever the method 

 of the artists contributing them, 

 the illustrations previously in 

 vogue being the work only of 

 draughtsmen on wood. 



On the art side The Graphic has 

 numbered on its staff Henry Woods, 

 Luke Fildes, Frank Holl, H. Her- 

 komer, E. J. Gregory, James D. 

 Linton, E. J. Poynter, and Phil 

 May ; while its literary contributors 

 have included Edmund Yates, 

 G. A. Sala, Anthony Trollope, 

 Charles Reade, Victor Hugo, 

 Wilkie Collins, George Meredith, 

 Thomas Hardy, William Black, 

 Bret Harte, Walter Besant, J. M. 

 Barrie, and Rudyard Kipling. 

 Sydney P. Hall and Frederic 

 Villiers did splendid work for it 

 as war artists. J. M. Bulloch was 

 appointed editor in 1909. The con- 

 trol of the paper, together with 

 that of The Daily Graphic and 

 Bystander, passed from H. R. 

 Baines & Co., Ltd., in Nov., 1919, 

 to W. E. and J. G. Berry. 



Graphic Statics. Method used 

 for obtaining the relations between 

 forces, external and internal, acting 

 on a body or framework in engin- 

 eering. Forces are represented in 

 magnitude and direction by straight 

 lines, and by compounding them 

 together according to the law of the 

 polygon of forces, the forces in any 

 part of a framework may quickly 

 be obtained. The representation 

 of these forces is called the stress 

 diagram, and from it can be ob- 

 tained by direct measurement the 

 force in any particular member of a 

 structure, as a bridge. See Graphical 

 Statics, L. Cremona, Eng. trans. 

 L. H. Beare, 1913; Theory of 

 Structures, A. Morley, 1918. 



Graphite OR BLACK LEAD. 

 Mineral form of carbon, soft, grey 

 or black in colour, with greasy 

 touch. Scheele, in 1779, showed 

 the true nature of graphite, which 

 when pure is entirely converted 

 into carbonic acid gas just as the 

 diamond. It occurs in nature in 

 various parts of the world. The 

 deposits at Borrowdale in Cumber- 

 land were for many years the chief 



source of the graphite used for 

 black-lead pencils. Large quantities 

 are found in Ceylon and the United 

 States of America. 



For making pencils, graphite was 

 originally employed in the form of 

 slips cut from blocks of graphite, 

 but to use up the graphite powder 

 obtained as a by-product other 

 methods were adopted. Finely 

 sifted graphite is blended with 

 other substances according to the 

 hardness of the pencil required. 



Plumbago crucibles are made 

 largely from Ceylon graphite mixed 

 with Stourbridge clay. The mass is 

 worked up with water, and then 

 left to mature for some weeks, after 

 which the crucibles are shaped by 

 the method familiar to potters, and 

 afterwards dried arid fired. The 

 advantage of plumbago crucibles 

 in metallurgical operations is that 

 they stand changes of temperature 

 without cracking, and do not 

 absorb any of the metal which is 

 melted in them. The variety of 

 graphite known as gas carbon is 

 deposited in the upper parts of 

 the retorts used in the manufacture 

 of coal gas and in blast-furnaces. 

 Very hard, it is employed for 

 making carbons for the arc electric 

 light and as electrodes in batteries. 



The use of graphite as a stove- 

 polish is familiar. Ceylon graphite 

 is mixed with lamp-black into a 

 paste by means of vinegar and tur- 

 pentine; the lamp-black neutral- 

 ises the silvery lustre which is pro- 

 duced by Ceylon black-lead alone. 

 See Carbon. 



Graphotype (Gr. graphein, to 

 write; typos, impression). Process 

 of making drawings in the form of 

 a relief from which stereotypes may 

 be taken. The drawing was done 

 on the surface of compressed chalk 

 with a special ink, the chalk after- 

 wards being brushed away, leaving 

 the lines of the design in relief. 

 The process is now obsolete. 



