34 



NA TURE 



[Mav 



12, 



Albert Charles Seward, 



M.A. (Cantab.), F.G.S. University Lecturer in Botany, Cam- 

 bridge. Has made extended researches in Fossil Botany, the 

 results of which have been published in a series of papers and 

 ■works, of which the following may be specified : — That on the 

 Wealden Flora gives, for the first time, a critical and compre- 

 hensive view of the vegetation of this important geological 

 period, and in many respects enlarges and modifies our previous 

 knowledge of the subject : "On Calaviites undulatus'" {Geol. 

 Mag., vol. v., 1888) ; " Notes on Loviatophloios macrolepidotus, 

 iGoldg." {Proc. Camh. Phil. Soc, vol. vii., 1890); ".Fossil 

 Plants as Tests of Climate" (Sedgwick Prize Essay for 1892) ; 

 "On the Q,&xs.\i.% Myeloxylon, Brong." {Annals of Botany, vol. 

 vii., 1893); "On Rachiepterts Williamsoni, sp. nov., a new 

 Fern from the Coal Measures" {ibid., vol. viii., 1894) ; "Cata- 

 logue of the Mesozoic Plants in the Department of Geology, 

 British Museum (Nat. Hist.)" ; "The Wealden Flora, Part I., 

 Thallophyia to Pteridophyta. Part H., Gymnospermae " 

 < 1894-95)- 



William Ashwell Shenstone, 



F.I.C., Senior Science Master in Clifton College. Member of 

 Council of the Chemical Society. Distinguished for his skill as 

 an experimenter, for his ability as a teacher, and for his zeal in 

 the introduction of improved methods of teaching physical 

 science as a branch of general education. Author of the 

 following and other papers : — " Ozone from Pure Oxygen " 

 {Jount. Chetn. Soc, 1887); "The Volumetric Relation of 

 Ozone and Oxygen," "The Influence of Temperature on the 

 Composition and Solubility of Hydrated Calcium Sulphate and 

 Calcium Hydroxide" {Journ. Ckem. Soc, 1888); "Some Im- 

 proved Vacuum Joints and Taps" {ibid. , i'&<)o) ; " Platinous 

 Chloride as a Source of Chlorine," "The Adhesion of Mer- 

 cury to Glass in the presence of Halogens" {Journ. Chem.Soc, 

 1892) ; "On preparing Phosphoric Anhydride free from the 

 Lower Oxides of Phosphorus," "Studies on the Formation of 

 Ozone from Oxygen," Part II. {Journ. Cheni. Soc,_ 1893). 

 Also author of the article on Ozone in the current edition of 

 Watts' Dictionary ; " A Practical Introduction to Chemistry" 

 (Rivington, 1886); "The Methods of Glass Blowing" 

 (Rivington, 1886) ; Life and Work of Liebig" (Century Series, 

 Cassell, 1895). 



Henry Martyn Taylor, 



Barrister-at-Law. Fellow of Trinity College, Cambridge. For- 

 merly Tutor of Trinity College, Cambridge. Third Wrangler 

 gnd Second Smith's Prizeman in 1865. Author of papers in the 

 Mathematical Messenger, as follows : — Vol. iii. p. 189, "Geo- 

 metrical Explanation of the Equations for the Longitude of the 

 Node and the Inclination of the Orbit"; vol. v. p. i, 1876, 

 ■" On the Generation of Developable Surface through Two given 

 Curves"; vol. vii. p. 22, 1877, "On Certain Series in Tri- 

 gonometry"; vol. vii. p. 145, 1877, "On the Porism of the 

 Ring of Circles touching Two Circles"; vol. xi. p. 177, "On 

 a Six-point Circle connected with a Triangle " ; vol. xiii. p. 

 145, "On a Cubic Surface"; vol. xvi. p. 39, "On a Geo- 

 metrical Interpretation of the Algebraical Expression which, 

 equated to Zero, represents a Curve or a Surface " ; vol. xvi. 

 p. 143, "Extension of an Inversion Property." In the Pro- 

 ceedings London Mathematical Society : Vol. v. p. 105, 1874, 

 " Inversion, with Special Reference to the Inversion of an 

 Anchor Ring or Torus"; vol. xiii. p. 102, "A Geometrical 

 Theorem concerning the Division of a /-gon into w-gons (with 

 R. C. Rowe); vol. xv. p. 122, "The Relations of the Inter- 

 sections of a Circle with a Triangle " ; vol. xx. p. 422, a Geo- 

 metrical note " On the Developable Surface through Two 

 Conies Inscribed (or Escribed) in Two of the Faces of a Tetra- 

 hedron." In the Quarterly Journal of Mathematics : Vol. xxiv. 

 P- 55) " On the Centre of an Algebraical Curve " ; vol. xxvi. 

 p. 148, " Orthogonal Conies " ; vol. xxvi. p. 214, "Orthogonal 

 ■Quadrics." In the Philosophical Magazine: Vol. 1. p. 221, 

 1876, " On the Relative Values of the Pieces in Chess." Philo- 

 sophical Transactions, vol. clxxxv. pp. 37-69, 1894, "On a 

 Special Form of the General Equation of a Cubic Surface " ; 

 and " On a Diagram representing the Twenty-seven Lines on 

 the Surface." Writer of the article on Geometrical Conies in 

 the last edition of "Encyclopaedia Britannica," editor of 

 " Elements of Euclid " for the Syndics of the Cambridge Uni- 

 versity Press; author of two treatises — "On Great-Circle 

 Sailing " ; " On a Method by which a Steamer's Lights might 

 show her Course." 



James Wimshurst. 



Member of the Consultative Stafi^, Board of Trade. Qualifica- 

 tions : (i) Improvements in Electrical Influence Machines, 

 which are now universally approved and adopted by Physicists ; 

 (2) an Influence Machine which gives charges of electricity, 

 alternating from positive to negative with each rotation of the 

 disc (in this type the glass discs, without any metal upon them, 

 are freely self-exciting) ; (3) has delivered a lecture upon 

 Influence Machines at the Royal Institution, April 27, 1888, 

 and read papers at the Physical Society, April 17, 1891, and 

 June 22, 1893. 



NO. 1489, VOL. 58] 



THE FLOW OF WATER. 



TV/TORE thati one hundred years ago, the French 

 ^^ philosopher Coulomb caused a disc suspended by 

 a torsion wire to oscillate in a vessel of liquid, and he 

 thus ascertained that the resistance to various bodies 

 under such circumstances, when the movement is a slow- 

 one, varies directly as the velocity of the motion. This 

 law of resistance, it should be noted, is quite contrary to 

 that of the friction between solid bodies as investigated 

 by General Morin. Colonel Beaufoy, Froude, and others, 

 however, found that, at higher velocities, the resistance 

 varied more nearly as the square of the velocity. The 

 difference of the two conditions in which the variation 

 was directly, or, as the higher power, undoubtedly repre- 

 sented on the one hand the condition of water in which 

 the mere viscosity came into play, resisting the shearing 

 stress of the layers in passing over each other, and on 

 the other hand the condition when the breaking up of the 

 water into eddying motion caused the resistance to 

 become much greater. 



Prof. Osborne Reynolds, about 1883, investigated 

 the critical velocity at which this change of state occurs, 

 and gave calculations concerning the critical velocity, 

 accompanied by an account of some beautiful experi- 

 ments. These experiments showed the sudden breaking 

 up at the critical velocity of the stream in a glass tube, 

 the water in which had been flowing quite steadily until 

 that particular velocity was reached. 



Now with water flowing in a tube or channel with 

 wetted sides the velocity is greatest in the middle, and, 

 according to the generally accepted theory, is zero at the 

 sides. If this be the case, it would seem that in no event 

 can the whole body of water in the tube break up into 

 sinuous motion ; for it is evident that, although it is 

 possible to have one of the conditions by itself, viz. the 

 condition of lower velocity and parallel flow, it is not 

 possible to have the other condition by itself, viz. the 

 condition of sinuous flow. This leads irresistibly to the 

 conclusion that at some point or other there must be a 

 surface of separation between the two. 



Such a surface of separation obviously requires special 

 means in order to make it visible. When colouring 

 material is introduced into water flowing under ordinary 

 conditions, it mixes up at once throughout the whole 

 mass. If, however, air is injected into the water, it 

 has been recently found that, in the portion in which 

 the sinuous state exists, the small particles of air, which 

 appear when viewed by the eye as a sparkling mass, 

 prevent the transmission of light and reveal on a screen, 

 when a special lantern apparatus is employed, the actual 

 behaviour of the flowing water. Figs, i and 2 show a 

 rectangular body placed in the stream under such 

 conditions. The lines of flow in Fig. 2 result from the 

 use of slightly soapy water, which is used for the produc- 

 tion of air bubbles ; whereas in Fig. i the air is injected 

 into perfectly clear water, and larger bubbles are con- 

 sequently formed. 



Now, if the above figures are examined, it will 

 be seen that round each there is a clear border 

 line indicating a condition diflering from that in the 



