June 25, 1891] 



NATURE 



187 



values of e and the mean intensities of the lines at the two sta- 

 tions. The scale of intensity is such that the C line = lo, and 

 the line at 651 "55 is unity. 



Place of Intensities of 



observation. Altitude. e. the lines 



A. B. o. 

 Bosco Nero ... 1623 metres ... loafiz ... 50 28 3'2 

 Rocciamelone . . . 3538 8462 ... 40 20 2'2 



A comprehensive bibliography of the subject accompanies the 

 paper. 



Similarity OF THE Orbits of Certain Asteroids. — In 

 the Pul'lications of the Astronomical Society of the Pacific, 

 No. 15, 1891, Prof Daniel Kirkwood gives a list of twenty-four 

 asteroids arranged in ten groups, according to the similarity of 

 their orbits. The following are the groups : — 



( 84 Clio. 



I. ] X15 Thyra. 



f 249 Use. 



jj / 19 Fortuna. 



■ \ 79 Eurynome. 



jjj r 134 Sophrosyne. 



' \ 193 Ambrosia. 

 ,Tv 5 37 Fides. 

 ^^- ( 66 Maia. 



|'2i8 Bianca. 

 V. - 204 Callisto. 

 (^ 246 Asporina. 



VI \ 3 Juno. 

 ^^- ) 97Clotho. 

 VII \ ^°^ Pompeia. 

 I 200 Dynamene. 

 ( 278 Pauline. 

 VIII. \ ii6Sirona. 

 f I Ceres. 

 I 245 Vera. 

 IX. \ 86 Semele. 

 ( 106 Dione. 

 Y \ 121 Hermione. 

 ^- i 87 Sylvia. 



Jupiter is held responsible for the perturbations necessary for 

 the development of these groups of asteroid orbits from the 

 primitive solar nebula. 



Astronomical and Physical Society of Toronto. — 

 The first number of the Transactions of this Society (1890-91), 

 with which is also included the first Annual Report, has recently 

 been issued. It contains abstracts of several interesting papers 

 read at the meetings, among which is one on the disappearance 

 of Saturn's rings, by Dr. Morrison, two by Mr. Shearman on 

 coronal photography, and two by Mr. A. F. Miller on the 

 spectroscope. A drawing of a sun-spot observed on November 

 30, and a hydrogen prominence measured on August 3, forms 

 the frontispiece of the number. 



A New Asteroid («i).— On June 11 M. Charlois discovered 

 the 311th asteroid. Its magnitude was 13. 



THE ROYAL SOCIETY CONVERSAZIONE. 



'T'HE Ladies' Soiree of the Royal Society was held on the 

 ■*■ 17th instant, and was very numerously attended. The 

 followiug were among the chief objects exhibited : — ■. 



Finger-prints as a means of identification, exhibited by Mr. 

 Francis Gallon, F.R.S. (i) Specimens showing the nature and 

 character of the patterns that are formed by the papillary ridges 

 on the bulbs of the fingers, as well as on the rest of the inner 

 surfaces of the hands and feet. (2) Evidence of the persistence 

 of the patterns in their essential details, however minute, from 

 infancy to age. (3) Method of indexing a collection of finger- 

 prints so that a determination may be quickly arrived at, whether 

 the duplicate of a given specimen is contained in it or not. (4) 

 Process of making finger-prints, exhibited in operation. 



Registration of colours in numbers, and apparatus to show the 

 greater sensitiveness of the eye to different colours, exhibited by 

 Captain Abney, C.B., F.R.S., and General Festing, F.R.S. 

 The registration consists in referring any mixed colour to a 

 single wave-length, and a percentage of white light. With the 

 apparatus to show the greater sensitiveness to the eye of different 

 colours, a comparison is made by placing two colours side by 

 side, which are at ordinary intensity of equal luminosity, and by 

 then diminishing the intensity of each equally. 



An optical illusion, exhibited by Prof Silvanus P. Thompson, 

 F.R.S. On two rotating disks, A and B, are spiral patterns in 

 black and white, which seem to move radially inwards and out- 

 wards respectively. Let the observer gaze fixedly for about one 

 minute at the centre of A, and then suddenly transfer his gaze 

 to any object — say the face of a friend — he will see that object 

 apparently enlarging from the middle outwards. After similarly 

 gazing for a minute at B, and then looking at any object, he will 

 see it apparently diminishing. 



NO. 



I I 30, VOL. 44] 



Discharge without electrodes through gases, exhibited by Prof. 

 J. J. Thomson, F.R.S. The discharge tube in these experi- 

 ments is made to form the secondary of what is essentially an 

 induction coil, and the discharge passes round a closed current 

 in the gas. Experiments a, h, c, d show various forms of the 

 discharge in tubes and bulbs, e shows the residual glow pro- 

 duced when the discharge passes through oxygen. / shows the 

 action of a magnetic field on the discharge ; along the lines of 

 force the discharge is facilitated, while at right angles to them it 

 is retarded. When the magnetic field is "off," the discharge 

 takes place in the bulb, and not in the tube ; when the field is 

 "on," in the tube, and not in the bulb, g illustrates the 

 stoppage of the discharge when a gas electrically weaker than 

 that in the discharge tube is placed in the neighbourhood of the 

 latter. 



A nickel pendulum, illustrating the effect of heat upon the 

 magnetic susceptibility of nickel, exhibited by Mr. Shelford 

 Bidwell, F.R.S. Nickel, which at ordinary temperatures is a 

 magnetic metal, becomes non-magnetizable at about 300° C. A 

 copper disk, to which a projecting tongue of nickel is attached, 

 hangs like the bob of a pendulum from a double thread, and is 

 deflected to one side by a magnet which attracts the nickel 

 tongue. The heat of a spirit-lamp placed beneath the tongue 

 quickly destroys the magnetic quality of the nickel, so that the 

 magnet can no longer hold it ; the bob accordingly falls back and 

 performs an oscillation. On its return to the neighbourhood of 

 the magnet, however, the tongue has cooled sufficiently to be 

 once more attracted, but after a momentary contact it is again 

 released, and the process is repeated. Thus the bob can be 

 kept swinging like the pendulum of a clock. 



The meldonieter, exhibited by Mr. J. Joly. This instrument 

 is for determining the melting-points of minute quantities of 

 substances, by comparison with bodies of known melting-point. 

 The method consists in measuring the thermal expansion of a 

 ribbon of pure platinum when a minute quantity of a substance, 

 dusted on its surface (and observed through a microscope), is 

 meliing. The platinum is heated by a current, and the thermal 

 value in degrees Centigrade of its expansion found by preliminary 

 observations, using bodies of known melting-point. The ex- 

 pansion of the ribbon is read by an electric-contact method. 

 The instrument shown reads a change of 2' C. Range up ta 

 1600" C. about. Quartz may be melted on the meldometer, and 

 most or all of the silicated minerals. 



Facsimile drawings of paintings from tombs at Beni Hasan, 

 Upper Egypt, exhibited by Mr. Percy E. Newberry (of the 

 Egypt E.xploration Fund). A series of facsimile drawings in 

 colour, executed by Mr. M. W. Blackden, of some of the most 

 interesting paintings on the walls of the tombs of Ameni and 

 Khnumholep (XII. Dynasty, cii-ca 2500 B.C.), at Beni Hasan, 

 in Upper Egypt. These drawings are the property of the Egypt 

 Exploration Fund. 



Instrument for examining the strains in bent glass beams,, 

 exhibited by Prof C. A. Cams- Wilson. There is a steel strain- 

 ing frame in which the beam to be examined is placed ; this 

 frame can be moved in any direction in its own plane between 

 two Nicol prisms. The Nicol prisms can be rotated through 

 any required angle. When the beam has been supported in 

 any given manner, load is applied by a screw, and the action of 

 the strained glass on the polarized light enables the precise state 

 of strain all over the beam to be ascertained. The instrument 

 has been used to determine the action of "surface loading," and 

 to show to what extent this action affects the state of strain 

 in beams supposed to obey the Bernoulli- Eulerian theory of 

 flexure. 



Cup-micrometer, an instrument for measuring the rate of 

 growth of a plant, exhibited by Mr. Francis Darwin, F.R.S. 

 A thread is attached to the upper end of the plant, passes over 

 a pulley, and is fastened to a weight. The descent of the 

 weight (which is a measure of the growth of the plant) is esti- 

 mated by adjusting a micrometer screw carrying a small cup of 

 oil, until a needle point on the weight touches the surface of the 

 fluid. The method, a modification of that used by physicists to 

 measure the rise or fall of a fluid surface, was designed by Mr. 

 H. Darwin, of the Cambridge Scientific Instrument Company. 



Electrical volatilization of metals, exhibited by Mr. W. 

 Crookes, F.R.S. 



Living animals from the aquarium of the Marine Biological 

 Association at Plymouth, exhibited by the Marine Biological 

 Association. 



Art metal work, from the factories of Messrs. Tiffaoy and Co., 



