Jnne 19, 1879] 



NATURE 



187 



Baeyer and Emmerling obtained a red-colouring matter from 

 isatin, which they named indigopurpurin ; this is identical with 

 indirubin obtained by the author from indicau. The author 

 considers that the name indigopurpurin should be abolished. 



Physical Society, May 24. — Prof. W. G. Adams in the 

 '- chair.— New Members: Mr. Sedley Taylor, M.A., and Mr. 

 Walter Emmott, A.S.T.E.— Mr. W. J. Wilson exhibited a new 

 harmonograph and figures drawn by it. The figures drawn by 

 prior harmonographs are all more or less imperfect owing to loss [ 

 of motion in the pendulums actuating the marking pen ; and Mr. 

 Wilson therefore designed a new harmonograph which not only 

 gives perfect figures but admits of the phase of either of the two 

 compounded motions being decreased by a known amount. In 

 this instrument toothed wheels take the place of pendulums, the 

 ratio of the teeth giving the ratio of the periods of the motions. 

 By employing the device of an intermediate wheel gearing with 

 two others, and arranging two or more wheels on the intermediate 

 axle, a great variety of phase can be obtained for each motion. 

 An ingenious adjustment by means of a movable nut allows the 

 phase of either or both motions to be altered to a known extent, 

 and thus an endless variety of figures can be obtained. As in 

 other harmonographs a writing-table on which the paper is 

 placed, and an aniline glass pen, are used. Several of the figures 

 done also on glass were thrown on the screen, the stereoscopic 

 effect being very apparent. In reply to a query Mr. Wilson said 

 that he had adapted some of the figures to the stereoscope. — 

 Prof. Hughes explained his new induction balance and showed 

 some of its principal effects. It is well known that on starting 

 an electric current along a wire adjacent to another wire, an 

 induced current is set up in the second wire in an opposite direc- 

 tion to the first or primary current. In the induction balance 

 two primary circuits or coils are taken, with the same current 

 (interrupted by a microphone acted upon by the ticking of a clock) 

 running through both, and between these is placed a secondary 

 circuit or coil in connection with a telephone. The primary coils 

 are so wound as to oppose each other's induction on the inter- 

 mediate secondary. There is a point, moreover, between these, 

 where these opposed inductive influences exactly neutralise each 

 other. If the secondary coil be placed there, no induced ticking 

 of the clock can be heard ; but if the secondary be displaced to 

 one or other side of this point, the ticking can be heard in the 

 telephone increasing in loudness as the secondary approaches 

 one or other of the primaries. If the distance between the 

 primaries be graduated into a scale, this contrivance becomes a 

 sonometer, since it gives an absolute zero of sound, and degrees 

 of loudness. It is well adapted for measuring the hearing 

 ! lower of the ear. By splitting the secondary coil into two parts 

 uid placing each close to its proper primary, so that there are 

 iVjur coils in all arranged in two pairs, the extremes in one 

 primary circuit, and the means in one secondary, the two 

 opposing parts of the balance can be separated from each other, 



ISO as not to disturb each other's action, and the balance made 

 very sensitive by the closeness of the primaries and secondaries. 

 Prof. Hughes finds that there is a line or zone of maximum in- 

 duction midway between each primary and its secondary. If a 

 conductor such as a piece of metal be put in this position it has 

 a maximum disturbing effect on the balance, due probably to the 

 electric currents generated in it by the induction. The effect is 

 apparently proportional to the conductivity of the metal. It 

 requires an exactly similar piece of metal put between the other 

 pair of coils to restore the equilibrium of the balance. A differ- 

 ence of alloy, or of weight between two like coins is at once 

 observed from the imperfect restitution of the balance ; base 

 coins are thus also at once detected. Again, it is possible for a 

 person to tell what particular coin or coins are in one part of the 

 balance by trial of the same coins in his part. When plates of 

 non-magnetic metals are held vertical in the balance their dis- 

 turbing effect is tiU ; uron on the other hand gives its maximum 

 effect on this position, because its magnetic effect overbalances 

 Its electrical effect. Two pieces of iron may therefore neutralise 

 each other as cores in an induction coil. Steel is easy to 

 balance compared with soft iron. Zinc disturbs most when 

 placed along the sides of each pair of coils ; iron when in centre 

 at a certain length of metal laid along the outsides of the coils 

 produces silence. The maximum line of inductive force is mid- 

 nay between the coils, and there is a line of minimum force at 

 I lialf the thickness of each coil. A metal placed at these lines of 

 u minimum force has no disturbing eflect on the balance. Pressure 

 P applied to small shot, or spongy gold, alters the balance. The effects 

 of stress, heat, magnetism, light, &c. , on matter could be determined 



by the balance. Prof. W. G. Adams believed that one result of Prof. 

 Hughes's experiments will be the determination of the way in 

 which the law of electro -dynamic induction depends on density. 

 He also imagined that the metal when in the maximum line 

 between the coils gathered the lines of force to itself, whereas 

 when on the minimum lines it could not thus divert them. Prof. 

 Ayrton cited the early experiment of Faraday with a sheet of 

 copper oscillating to rest between two opposite magnetic poles. 

 The copper took a long time to stop ; but a sheet of iron placed 

 between two like poles was soon stopped owing to its becoming 

 imbued with an opposite polarity, and deflecting the lines of 

 force. He also suggested that the divergence of the results for 

 conductivity of metals got by the induction balance from those 

 got by the Wheatstone balance might be due to that electric 

 inertia suspected by Sir William Thomson. Prof. Guthrie 

 thought that the induction balance pointed to the conclusion that 

 the disturbing effect of a conducting mass applied in this way is 

 proportional to the quantity of electricity generated in it under 

 certain conditions of temperature, &c. The determination of 

 the conductivity of liquids would be a useful application of the 

 balance. Mr. Chandler Roberts gave some results which he 

 had obtained from an examination of certain alloys by means of 

 the induction balance. He had been able to detect a difference 

 of one part in 1,000 in the amount of silver in two shillings 

 of equal weight. He also pointed out that Mathiessen divided 

 alloys into three classes: (i) solidified solutions of one metal 

 in another ; (2) solidified solutions of one metal in an allo- 

 tropic modification of another metal ; (3) solidified solutions of 

 allotropic modifications of both metals. For the first class the 

 curve of electric conductivity is a straight line, for the second a 

 parabolic curve, for the third a bent line. Mr. Roberts found 

 that the balance gave the characteristic curve for the first class 

 with an alloy of lead and tin, and for the second with an alloy 

 of gold and silver. With a copper tin alloy, which is a good ex- 

 ample of the third class, he found the curve given by the balance 

 to be intermediate between Alfred Risch's curve of density and 

 Mathiessen's curve of conductivity, and considers that the balance 

 is influenced by the density as well as the conductivity of the 

 metal interposed. Prof. Hughes said that as the working of 

 metals appeared to affect their conductivity he was inclined to 

 rely more on the conductivity measurements of the balance than 

 on those of the Wheatstone bridge. By the balance plain pieces 

 of metal were taken, whereas by the bridge wires were mostly 

 taken. He would rather not give any theory yet as to the 

 results obtained from the balance. — Dr. Erck then exhibited his 

 novel pump for lifting solutions out of batteries. It consists of 

 a closed vessel, funnel-like, the stem dipping into mercury, a 

 column of which ascends the latter to a certain height. Two 

 tubes emerge from the cover, one dipping into the liquid, the 

 other opening to the air. By altering the pressure inside the 

 vessel the solution rises to the latter, and can escape from it by 

 trickling through the mercury. 



Anthropological Institute, June 18.— Mr. Hyde Clarke, 

 vice-president, in the chair. — The following new Member was 

 announced : Mr. William Wavell, late of the Bengal Civil Service. 

 — A paper was read by Miss A. W. Buckland on some Cornish 

 and Irish prehistoric monuments. The authoress compared the 

 sepulchral and the non-sepulchral monuments existing in the two 

 countries, pointing out the differences between them, as indi- 

 cating, either that they were erected by different tribes, or at 

 various periods, and calling especial attention to the absence in 

 Cornwall of the round towers, so common in Ireland, as well as 

 of oghams, and those peculiar markings found in the Irish 

 chambered tumuli at New Grange, Dowth, &c., as also in 

 similar monuments in the north of Scotland and in Brittany. 

 These markings are believed by Miss Buckland to represent the 

 tribal or tattoo marks of the Picts or a kindred race, being one 

 of many different tribes brought by tradition from the neighbour- 

 hood of the Euxine, a tradition apparently confirmed by the 

 decidedly eastern characters of the jewellery found in Ireland, as 

 well as by the megalithic monuments which can almost all be 

 traced to Eastern Europe, and thence through Westera Asia to 

 India. Notwithstanding this apparently common origin. Miss 

 Buckland pointed out that they are almost everywhere arranged 

 in groups suggestive of a difference of race in their constructors, 

 and expressed a hope that some day a map of the world would 

 be constructed showing these groupings, which would be a great 

 help to students of ethnology and archaeology. — Mr. C. Pfoundes 

 also read a paper entitled "Some Facts about Japan and its 

 People," and exhibited drawings in illustration of the same. 



