io6 DESIGN IN NATURE 



Another plan is to cover a sheet of paper mth a thin layer of paraffin-wax, form the line of force picture, and 

 fix it by gentle heat. The pictures of iron-filings may also be photographed directly by sprinkling the finest iron 

 dust over the gelatine film of a bromide of silver dry plate in a dark room, by placing the magnet which produces 

 the fines of force on the dry plate, and by tapping the edges of the plate gently with a glass rod. When the 

 picture is formed the lodestone is removed, the plate exposed, and the image fixed in the usual way. 



I append two plates (Plates Iv. and Ivi.) containing fines of force representations of iron-fifings produced by 

 magnetic action ; my object in the present instance being to direct attention to the existence of " lines of force 

 in the inorganic kingdom in relation to similar fines of force which I befieve exist in the organic kingdom, as indicated 

 by the movements, growth, and structures in plants and animals. The inorganic fines of force can also be traced 

 in electric and analogous discharges (lightning flashes, electric sparks), in the formation of crystals, frost pictures, 

 dendrites in minerals and metals, &c., as seen in Plates xxix. to xxxvi. inclusive. 



"LINES OF FORCE" PLATES (Plates LV. and LVI.) 

 These plates contain representations of " lines of force figures " obtained by experiments with natural and 

 artificial magnets on iron-fifings and other substances. The fines of force figures remarkably resemble in their general 

 arrangement, and even in their details, sinular figures met with in crystals and in the several parts of plants and 

 animals. They point to general laws which govern equafiy the inorganic and organic kingdoms. They reveal 

 radiating or stefiate, curve, concentric, circular, and spiral arrangements, aU of which are found in dead and living 



matter afike. 



AH substances are magnetic (dia-raagnetic and para-magnetic), and it is difficult to say what precise part 

 magnetism and electricity play in the disposal, arrangement, and movements of the ultimate atoms and molecules 

 of animate and inanimate bodies. 



That the role performed by magnetism and electricity in the arrangements and movements of ultimate matter 

 is a leading and important one cannot be doubted. This becomes more apparent as the circle of the sciences 

 widens, and the relation of inorganic to organic matter becomes better understood. 



The " lines of force figures " are from Professor H. Ebert's work " Magnetic Fields of Force," translated 

 by C. V. Burton, D.Sc. (London and New York, 1897), but the inferences drawn from the figures are those of 

 the Author only. 



PLATE LV 



Fig. 1. — The dark, radiating, nearly straight and curved lines in this figure are due to the influence exerted by the lodestone or 

 natural magnet on iron-filings uniformly distributed over a horizontal sheet o£ white paper. Tliey represent the lines of force ; in 

 other words, the arrangement of the iron particles by the lodestone. The white patches a, h, c, d indicate the absence of iron-filings, 

 these having adhered to the lodestone when it was removed after the formation of the lines of force picture. 



Fig. 2. — Lines of force figure produced by the action of an artificial horse-shoe magnet on iron-filings, s, n, The poles of the 

 magnet ; i, region of least attraction or indifferent zone of the magnetic field. The lines of force are most marked at the poles. Here 

 they radiate in nearly straight and in graceful curved lines: the nearly straight lines proceeding from the outer corners of the poles — 

 the curved ones from the upper ends of the poles. At the central portions of the magnet the lines are nearly straight and transverse. 

 At the bend of the magnet the lines curve round and follow generally the outline of the bend. The lines in this region are less under 

 the influence of the magnet, and form its indifferent zone {i). 



Fig. 3. — Lines of force figure produced by the action of a lodestone or natural magnet on iron-filings : the poles of the magnet being 

 armed with pole pieces and rods of soft iron to concentrate and increase their power, s, n, The poles of the magnet. In this figure, 

 the radiating and curved arrangements are seen to perfection. The curves are best seen between the poles. They resemble centres of 

 development in crystals and of growth in plants and animals. Compare with Plates i., ii., iii. and iv. 



Fig. 4. — Lines of force figure produced by the action of an artificial round bar-magnet on iron-filings when the bar-magnet is held 

 in a vertical position. Shows concentric and radiating arrangements of the iron-filings similar to those met with in crystals, 

 in the stems, branches, and other parts of plants, and in the bones, teeth, and other parts of animals in cross section. Compare 

 with figures in Plates i. to v. inclusive. 



Fir. 5.— Lines of force figure of the earth considered as a natural magnet, x, Centre of the earth. The axis of the earth is 

 indicated by the short oblique lines proceeding inward from the periphery of the figure, n, s, North and south poles of the earth, 

 where the lines of force are most numerous and intense : they radiate and curve round, those from the north pole curving round and 

 re-entering the earth at the south pole. The lines of force are feeblest at a, a ; those regions representing the indifferent zones of the 

 magnetic field. 



Fig. 6.— Lines of force figure produced by an artificial bar-magnet acting on iron-filings as seen in a horizontal plane parallel to 

 the axis of the magnet, s, n, The polar regions, or centres of greatest magnetic intensity ; j, the centre of least magnetic intensity 

 (indifferent zone). Shows the radiating, nearly straight, and curved arrangements in a striking manner. The curves are most marked 

 between the poles, where they form incipient concentric rings ; they are least marked and straightest at the outer edges of the poles. 

 The arrangement is that seen in the formation of many crystals and' at growing centres in plants and animals. 



Fig. 7. — Lines of force figure obtained by two conductors passing perpendicularly through a plane of paper and iron-filings with 

 a little bar-magnet or needle placed near, whose axis points directly towards the axis of the conductors. Cj, C2, Spots at which the 

 conductors pass perpendicularly through the paper and iron-filings. At Cj the current passes from below upwards and embraces the 

 fonductor in a direction the reverse of that in wliich the hands of a clock move, At c.^ the current passes from above downwards and 



