beautiful effect." Most observers, in describing the colours of ridescent bodies, do so by attempting to depict the varied ffects produced by casually changing the position of he object in relation to the light, omitting to mention the xact sequence of the play of colours, or the relation of these olours to the direction of the iridescent light, i.e., whether prouced by perpendicular or oblique illumination. Here is a escription of the tufted neck humming bird, Trochilus ornatus, aken haphazard from a well-known work :-"The throat is of fine green colour, variable in different lights to a golden hue with a yellow or brown metallic lustre, and below that the hole of the belly is a rich brown, glossed with green, and olden." Such descriptions as the above, which happen to be he first I met with in seeking for an instance, are vague, and il to give a definite idea of the appearance of the object. But agueness in the description of these objects is not the only esult of the changing character of their colours. As might e expected, where such variation in appearance exists, the escriptions of different authors are almost as variable as the olours. Few attempt descriptions without acknowledging he hopelessness of the task. Thus Jardine, after describing his humming bird, Chryslampis mosquitus, remarks:-"It is mpossible to convey by words the idea of these tints, and aving mentioned those substances to which they approach earest, imagination must be left to conceive the rest.' And I dduce this quotation as fairly expressing the feeling of aturalists in reference to the description of iridescent objects enerally. Recognizing the admitted inability of observers to onvey by description an idea of the appearance of these iriescent objects, and having myself, for many years, constantly xperienced the same difficulty, I have been led to adopt a ethod for the examination of such objects, which, whilst xtremely simple and available in its application, yields unvarying esults with different ob ervers, results, moreover, which admit f the simplest description. Before describing this method, I may say that long experience the examination of iridescent objects has proved to me that, most without exception, the colours of natural iridescent bjects are due to interference produced by thin plates. In rder, therefore, to render clear the principles on which the ethod I propose is founded, I will briefly refer to certain funamental facts in connection with colour production by thin lates, and for this purpose will select a thin film of mica, which ith light at perpendicular incidence, appears red, iridescent d. If, now, this plate be inclined so that the light falls on at a more oblique angle, it is, of course, reflected at the same ngle, and now appears orange, and if the plate be still further clined, the reflected light appears yellow, then yellowish reen, green, and bluish green, and if the light were not too opiously reflected from the first surface to allow of perceptible terference by further inclination of the plate, all the colours the spectrum in their proper sequence might be observed. he same results, but much more vividly, may be seen in these ystals of chlorate of potash. Thus, we see that by rendering e incident light more and more oblique, the reflected light anges from a lower to a higher tint, that is, from the red wards the violet end of the spectrum. And this is what curs in the case of all iridescent bodies, as the incident ht becomes more oblique the colour changes to the tint above in the spectral order, so that, if we know what colour any ch object appears when seen at a certain angle, we can infer at colour it will change to on varying the incidence. This tle (Sagra purpurea), for instance, is red at perpendicular idence, it will, therefore, appear orange yellow and green en examined by successively increased obliquity of light. d the same is true of all other iridescent red objects. If object at perpendicular incidence be green, as in the case his beetle (Bupristis), it will become blue and then violet he incidence is increased. We thus see that an iridescent ect varies in colour, simply because it is examined by light dent, and therefore reflected, at different angles. Thus, erent observers see the same iridescent object of a different our, when they view it illuminated by light at a different le of incidence. If, however, the object is seen by all at same angle of the incident light it will present the same ur, and this is, in fact, what the method I propose ensures, that iridescent objects shall always be seen by light at one the same angle of incidence. The angle I select is one of so that the incidence and reflection are normal or perpenlar to the reflecting surface. By selecting this angle all trouble of measuring angles is avoided, since we know that the incidence is perpendicular when it coincides with reflection. Now, the reflected light may be made to coincide with the incident light by reflecting it on to the object by means of a mirror, and so adjusting the object that the light reflected from it passes to the eye through a perforation in the mirror. When examined in this way iridescent objects are marvellously altered in appearance, their changing colours are replaced by one fixed tint, visible only in one position, a fact which serves at once to distinguish them from bodies coloured by absorption, which remain coloured whatever the relation to the incident light. Such methods of examining bodies scarcely takes more time than by the eye alone. The mirror may be attached to a spectacle frame so as to leave both hands free, such as the one I show, or may be a simple hand mirror. For objects too small to be seen by the unaided eye, I have so arranged the microscope that light is made to pass down the tube of the instru ment, through the object glass on to the objects, and by a special arrangement, so adjusted the position of the object that the light is reflected back again through the instrument to the eye. The method is thus available for macroscopic as well as microscopic objects. To illustrate the practical value of this plan of examination,. I have here a few objects exhibiting iridescent colours, which, by trial, will be found to give the following results :The crest of this humming bird, Chrysolampis mosquitus, which, to the unaided eye, appears resplendent with all shades of red, orange, yellow, or green, according to the angle of the incident light, appears, when examined by the mirror, of one unvarying red tint, disappearing when the object is moved but absolutely unchanging in tint. Such an object, therefore, I should describe as "iridescent red"; all else regarding its colour may be inferred. Again, the breast, or gorget, of the same bird reflects all shades of orange, yellow, or green to the eye alone; with the mirror it is seen of a deep orange, which, as before, is unchanged in tints by any variation in position. Such an object I would describe as "iridescent orange." The gorget of another humming bird, Calliphlox amethystina, to the eye alone appears crimson, orange, yellow, or green with the mirror it is iridescent crimson only, spectroscopically a red of the 2nd order. Amongst insects, instances of iridescent species are numberless, the results of examination are just the same as in other iridescent bodies. This butterfly, Morpho, to the eye alone appears either greenish-blue, blue, or violet, as its inclination to the light varies; examined with the mirror it appears green, and should be described as iridescent green, or iridescent bluish-green. This beetle, Foropleura bacca, appears any shade of red, yellow, or green to the eye alone; with the mirror only iridescent red. In this extraordinary beetle, Chrysochroa fulminans, we have all the colours of the spectrum in their natural sequence, beginning with red at the tip of the wing case, and ending with violet higher up the elytron. These colours vary in an indescribable manner when attentively examined at different angles of incident light with the eye alone; with the mirror the wing cases are seen to be coloured successively from base to tip iridescent green, yellow, orange, and red, and these tints remain unaltered by change of position of the object. This piece of Haliotis shell exhibits indescribable changes of colour with every movement, but the difficulty of description, though by no means removed, is immeasurably lessened by the use of the mirror. And the same with this specimen of iridescent iron ore, its colours, which vary to the unaided eye, remain unchanged when examined by the mirror. To simplify the description of iridescent objects, therefore, I would advocate the above method, and would describe the result of such examination by recording the colour observed by aid of the mirror, and prefixing the term "iridescent" to express the changing properties of the colour. Bearing in mind the unvarying nature of these changes, a far clearer idea may be formed of the appearance of these objects than from any attempted description of what is admittedly indescribable. Time and space are also economized by the omission of lengthy descriptions. The accuracy, and, therefore, the value of any description of colour, is always enhanced by mapping its spectrum; more especially is this true in the case of iridescent colours. This is easily done, and by applying such map to a spectral chart, the order of the colour, and therefore its tint, is apparent. In examining many objects, chiefly birds or insects, by means of the mirror as above described, apparent exceptions are repeatedly met with to the fact stated above, that the colour is invariable in tint and disappears by inclination of the body. Such instances are no real exceptions, but are due to the redecting plates being curved, or having pigmentary matter beneath them, or an opalescent medium above them. In this way some of the most extraordinary and beautiful colour effects it seems possible to conceive are produced. In examining objects with the perforated mirror a single light is necessary. The sun is of course the best, and the electric light probably almost as good. I frequently employ the limelight, but a good paraffin lamp may be used as a substitute. Ordinary gas is unsuitable. The light should be placed in front of the observer, its direct rays being prevented from falling on the cbjects by means of a book or partition of some kind resting on the table, and of such a height that the light can be seen above it. On placing the mirror to the eye the light may be reflected from the mirror on to the object, and the latter manipulated so as to reflect the ray back through the perforation in the mirror to the eye. The incidence is thus known to be normal, and the colour observed is the one to be recorded. UNIVERSITY AND EDUCATIONAL CAMBRIDGE.-The following letter has been addressed by the University of Cambridge to that of Padua, which is about to celebrate the tercentenary of Galileo's professorship :— Universitas Cantabrigiensis Universitati Patavinae S. P.D. Litteras vestras, viri doctissimi, GALILAEI GALILAEI Professoris vestri celeberrimi in laudem conscriptas vixdum nuper perlegeramus, cum statim in mentes nostras rediit non una Italiae regio viri tanti cum memoria in perpetuum consociata. Etenim nostro quoque e numero nonnulli urbem eius natalem plus quam semel invisimus, ubi Pisano in templo lucernam persilem temporis intervallis aequis ultro citroque moveri adhuc iuvenis animadvertit ; etiam Vallombrosae nemora pererravimus, ubi antea scholarum in umbra litteris antiquis animum puerilem imbuera; ipsa in Roma ecclesiam illam Florentinam intravimus, ubi doctrinae suae de telluris motu veritatem fato iniquo abiurare est coactus; Florentiae denique clivos suburbanos praeterivimus, ubi provecta aetate caeli nocturni sidera solus contemplabatur, ubi extrema in senectute diei lumine orbatus cum MILTONO nostro collocatus est, ubi eodem demum in anno mortalitatem explevit, quo NEWTONUS noster lucem diei primum suspexit. Hodie vero ante omnia non sine singulari voluptate sedem quandam doctrinae insignem, intra colles Euganeos urbemque olim maris dominam positam recordamur, ubi trecentos_abhinc annos saeculi sui ARCHIMEDES discipulorum ex omni Europae parte confluentium numero ingenti erudiendo vitam suam maturam maxima cum laude dedicavit; ubi, ut LIVII vestri verbis paulum mutatis utamur, ultra colles camposque et flumen et assuetam oculis vestris regionem late prospiciens, caelo in eodem, sub quo vosmet ipsi nati estis et educati, instrumento novo adhibito inter rerum naturae miracula primus omnium Lunae faciem accuratius exploravit, Iovis satellites quattuor primas detexit, Saturni speciem tergeminam primus observavit, altraque mandi orbem ingentem a Saturno lustratum fore suspicatas est ut etiam alii planetae aliquando invenirentur. Ergo vatis tam veracis, auguris tam providi in honorem, nos certe, qui Professorum nostrorum in ordine planetae etiam Saturno magis remoti ex inventoribus alterum non sine superbia nuper numerabamus, hodie alterum ex Astronomiae Professoribus postris, Georgium DARWIN, nominis magni heredem, nostrum omniam legatum, quasi Nuntium nostrum Sidereum, ad vosmet inses libenter mittimes. Vobis autem omnibus idcirco gratulamar quod tam Italiae totius, tum vestrae praesertim tutelae trada est viri tanti gloria, qui divino quodam ingenio praeditus rerum naturae in provincia non una ultra terminos prius notos scientiae humanae imperium propagavit quique caeli altitudines immensas perscrutatus mundi spatia ampliora gentibus patefecit. Valete. Datum Cantabrigit a dvaj Kal Decombres A. S. MDCCCXCIL Mr. F. Darwin has been appointed Deputy Professor of Botany for the current academical year, Prof. Babington being unable a lecture on account of the state of his health. SCIENTIFIC SERIALS. American Journal of Science, November.-Unity glacial epoch, by G. Frederick Wright. An examin the evidence in favour of two successive glacial epochs se by an inter-glacial epoch, during which the glaciated as free from ice as it is at the present time. This evid shown to be inconclusive, at least as far as American tions go. A photographic method of mapping the field, by Charles B. Thwing. Iron filings are strewn film side of a dry plate laid horizontally in a magnetic te the plate is exposed to light from above. The filings an brushed off, and the plate developed. From the negative lent lantern slides may be obtained.-Contributions to ogy, No. 54, by F. A. Genth, with crystallographic notes! Penfield. Description and analysis of aguilarite, m barrite, dollingite, rutile, danalite, yttrium-calcium cyrtolite, lepidolite, and fuchsite.—The effects of self-in and distributed static capacity in a conductor, by Fr Bedell, Ph.D., and Albert C. Crehore, Ph. D.-The tive determination of rubidium by the spectroscope, b Gooch and J. I. Phinney. The method is that of coz. photometrically the intensity of a certain line in the spec the metal under investigation with the intensity of that a standard solution containing a known amount of the me definite amount of the salt solution-usually the chr taken up by a hollow coil of platinum wire, which may to take up constant quantities of liquid by taking care to the coil while hot into the liquid, and removing it with inclined obliquely to the surface. The coils were made tinum wire o 32 mm. in diameter, wound in about him. to a spiral 1 cm. long by 2 mm. across, and twisted toge the ends to form a long handle. Each coil held o water. With such a coil, the blue rubidium lines were pr in a Muencke burner from o'0002 mgr. of the chloride. > test experiments showed that in the case of pure sout rubidium chloride the percentage could be found spec ally up to 1 part in 30,000 with an error as low as 1Z In presence of potassium or sodium, however, the may be as great as 20 per cent.-Notes on the mete Farmington, Washington County, Kansas, by H. L. Pr cent. A note on the cretaceous of North-western Montana Wood.-A deep artesian horing at Galveston, Texas, bri Hill.-Notice of a new Oriskany fauna in Columba C New York, by C. E. Beecher, with an annotated list of by J. M Clarke.-Description of the Mount Joy meteor E. E. Howell.-Influence of the concentration of the. the intensity of colour of solutions of salts in water, by Linebarger. SOCIETIES AND ACADEMIES. Royal Society, November 17.-" Stability and Irs: of Viscous Liquids," by A. B. Basset, F. R. S. (A —The principal object of this paper is to endeavour to a theoretical explanation of the instability of viscous which was experimentally studied by Professor Op Reynolds, 1 The experiment, which perhaps most strikingly illustra branch of hydrodynamics, consisted in causing water to a cistern through a long circular tube, and by means of sappliances a fine stream of coloured liquid was made down the centre of the tube along with the water. Whe velocity was sufficiently small, the coloured stream showe tendency to mix with the water; but when the veloci increased, it was found that as soon as it had attained a un critical value, the coloured stream broke off at a certar of the tube and began to mix with the water, thus shown; the motion was unstable. It was also found that as the w was still further increased, the point at which instabili menced gradually moved up the tube towards the end at t the water was flowing in. Professor Reynolds concluded that the critical veloc was determined by the equation Was μ<n, where a is the radius of the tube, p the density, ar viscosity of the liquid, and a number; but the results ↑ Phil. Trans. 1783, p. 935. = (1), ere n is a root of the equation J1(n)=0. Experiment shows that when the velocity is greater than out six inches per second, the frictional tangential stress of ater in contact with a fixed or moving solid is approximately oportional to the square of the relative velocity. This induces a constant 8, which may be called the coefficient of ding friction, whose dimensions are [ML-3], and are therefore e same as those of a density. This constant may have any sitive real value; 8 = o corresponding to perfect slipping or ro tangential stress, whilst B∞o corresponds to no slipping, hich requires that the velocity of the liquid should be the me as that of the surface with which it is in contact. Owing the intractable nature of the general equations of motion of viscous liquid, I have been unable to obtain a complete lution, except on the hypothesis that B is an exceedingly all quantity. This supposition, I fear, does not represent ry accurately the actual state of fluids in contact with solid dies; but at the same time the solution clearly shows that e instability observed by Prof. Reynolds does not depend on viscosity alone, but is due to the action of the boundary on a viscous liquid. To a first approximation, the real part of k is proportional to The results of the investigation may be summed up as lows: i.) The tendency to instability increases as the velocity of the uid, the radius of the tube, and the coefficient of sliding friction rease; but diminishes as th viscosity increases. 1.) The tendency to instability increases as the wave-length m) of the disturbance increases. The remainder of the paper is occupied with the discussion a variety of problems relating to jets and wave motion. find that when a cylindrical jet is moving through the atmoere, the tendency of the viscosity of the jet is always in the ction of stability. The velocity of the jet does not affect the ility unless the influence of the surrounding air is taken into bunt; if, however, this is done, it will be found that it gives to a term proportional to the product of the density of the and the square of the velocity of the jet, whose tendency is render the motion unstable. The tendency of surfaceon (as has been previously shown by Lord Rayleigh) is in direction of stability or instability according as the waveh of the disturbance is less or greater than the circumference e jet. in addition, the jet is supposed to be electrified, the conn of stability contains a term proportional to the square of harge multiplied by a certain number, ». When the ratio e circumference of the jet to the wave length is less than is positive, and the electrical term tends to produce ity; but when this ratio is greater than 06, n is negative, he electrical term tends to produce instability. It must, ver, be recollected that when the above ratio is greater than the tendency of surface tension is to produce stability; but if the influencing body is capable of inducing a sufficiently large charge, the electrical term (when 27a > λ) will neutralize the effect of surface tension and viscosity, and the motion will be unstable. The well-known calming effect of "pouring oil on troubled waters" has passed into a proverb. The mathematical investigation of this phenomenon is as follows:-The oil spreads over the water so as to form a very thin film; we may therefore suppose that the thickness of the oil is so small compared with the wave-length hat powers of higher than the first may be neglected. Also, since the viscosity of olive oil in C. G. S. units is about 3'25, whilst that of water is about 0014, the former may be treated as a highly viscous liquid, and the latter as a frictionless one. For olive oil, T1 = 20'56, T = 36'9, so that T > T1; and I find that the motion will be stable unless the wave-length of the disturbance lies between about 9/11 and 6/5 of a centimetre. This result satisfactorily explains the effect of oil in calming stormy water. In the critical case in which the denominator vanishes, the approximation must be conducted differently. OXFORD. University Junior Scientific Club, October 26.—Mr. E. L. Collis, in the absence of Mr. Bourne, gave an exhibit of Codium tomentosum.—Mr. F. C. Britten gave an exhibit of the nest of a trapdoor spider.-Mr. Hill read an interesting paper on the determination of sex, which was followed by a long discussion. Mr. Fisher exhibited some specimens of crystallized anhydrous oxalic acid, and described their methods of preparation. CAMBRIDGE. Philosophical Society, October 31.-Prof. G. H. Darwin, President, in the chair.-The following officers were elected for the ensuing session:-President: Prof. Hughes. VicePresidents: Dr. Cayley, Prof. G. H. Darwin, Dr. Hill. Treasurer: Mr. R. T. Glazebrook. Secretaries: Dr. Hobson, Mr. J. Larmor, Mr. Bateson. New Members of Council: Prof. Thomson, Mr. F. Darwin, Dr. Shore, Mr. Ruhemann.— The retiring President addressed the Society.-The following communications were made:-Note on the determination of low temperatures by platinum-thermometers, by Mr. E. H. Griffiths and Mr. G. M. Clark. The authors, following up the suggestion of Profs. Dewar and Fleming, that the resistance of certain pure metals vanishes at absolute zero, have assumed the possibility of extrapolating the platinum thermometer formulæ, and have thus found the temperature at which R=0. From the previously-published constants of seven different thermometers-including Callendar's original wire-the mean value deduced by them is 273° 86, which is in remarkable agreement with Joule and Thomson's thermodynamical value -2737. They further suggest that the simple method of determining the resistance in ice and steam and assuming R=0 when t=-273°7 is sufficient to graduate a thermometer con. structed of fairly pure wire, as they show that the errors so introduced will only amount to a fraction of a degree over the range-273° to + 150°.-Carnot's principle applied to animal and vegetable life, by Mr. J. Parker. The author discusses the question whether the conditions of the growth of plants are limited by the law of entropy. The assumption is made that Carnot's rinciple takes account only of the exchange of heat, and the temperature of the material system at which the exchange takes places; that the differential effect of solar radiation of different kinds consists in variation of the activity but not of the mechanical type of the growth. The increase of available energy due to the building up of inorganic materials into a plant can then only be explained, in conformity with the second law of thermodynamics, by the aid of differences of temperature during growth: the author gives calculations to prove that the difference between day and night is amply sufficient for this purpose.-Note on the geometrical interpre tation of the quaternion analysis, by Mr. J. Brill. 1 I Osborne Reynolds, Phil. Trans. 1886, p. 17. PARIS. Academy of Sciences, November 14.-M. d'Abbadie in the chair. Heat of combustion of camphor, by M. Berthelot. -Remarks on a note by M. A. Colson on the rotating power of the diamine salts, by M. C. Friedel.-Researches on the chemical constitution of the peptones, by M. P. Schützenberger. -Influence of the distribution of manures in the soil upon their utilization, by M. H. Schloesing.-On the laws of dilatation of gases under constant pressure, by M. E. H. Amagat. Tables are given of coefficients of expansion of carbon dioxide under pressures ranging from 50 to 1000 atm., and temperatures up to 258°; and for oxygen, hydrogen, nitrogen and air, under pressures up to 3000 atm. For CO, the coefficient has a maximum at a certain pressure for each range of temperature. This maximum corresponds to a higher pressure as the temperature rises. For the other gases the coefficient decreases regularly as the pressure increases. As regards temperature, the coefficient of expansion of CO, for each pressure reaches a maximum at a certain temperature and then decreases. This temperature is the higher, the greater the pressure. The more permanent gases behave as if they had already passed their maximum.Study of the pathogenic power of fermented beet-root pulp, by M. Arloing.-Observations of the new comet Holmes (f 1892), made at the Paris Observatory (west equatorial), by M. G. Bigourdan (see Astronomical Column).-Transformation of the great telescope of the Paris Observatory for the study of radial velocities of the stars, by M. H. Deslandres (see Astronomical Column).-Summary of solar observations made at the Royal Observatory of the Roman College during the third quarter of 1892, by M. P. Tacchini.-On the inversion of Abelian integrals, by M. E. Goursat.-On the summation of a certain class of series, by M. d'Ocagne.- On the equations of dynamics, by M. R. Liouville.-Experimental researches on the deformations of metallic bridges, by M. Rabut.-Conditions of equilibrium and of formation of liquid microglobules, by M. C. Malézos. The following experimental results were arrived at: When a liquid spreads over the free surface of a denser liquid, microglobules are produced on inverting the position of the two liquids. If a liquid rests in drops on the surface of a denser liquid, then in the inverse position the denser will spread over the less dense liquid.-Demonstration of the existence of interference of electric waves in a closed circuit, by means of the telephone, by M. R. Colson. A Rhumkorff coil was kept vibrating at 130 per second by a thermopile. To one of its terminals was attached a copper wire ending in a hook, to which a linen thread soaked in calcium chloride was attached by one end, the other hanging free. One of the terminals of a telephone was placed in contact with the thread, the other terminal being isolated. Under these conditions, the sound in the telephone was completely extinguished at a certain distance from the copper. When both the ends of the thread (which was 3 m. long) were connected up by fine copper wires, two points of extinction were reached, one from each end. On shortening the thread these points approached each other and formed a zone of extinction between them. This zone of extinction spread over the entire copper wires as the thread was shortened to zero. The neutral zone is due to interference of two waves of the same period and of equal potential meeting in opposite directions.-On the co-existence of dielectric power and electrolytic conductivity, by M. E. Cohn.-Observations on the preceding communication, by M. Bouty.-Magnetic properties of bodies at different temperatures, by M. P. Curie. These were measured by bringing samples of the bodies between the ends of two electromagnets inclined to one another, and measuring the forces experienced by means of a torsion balance. The bodies were heated in a porcelain crucible, the heat being supplied by platinum wires carrying a current, and measured by a Chatelier thermocouple.-On the propagation of vibrations through absorptive isotropic media, by M. Marcel Brillouin.On a new relation between variations of luminous intensity and the numerical order of the sensations, determined by means of a luminous paint, by M. Charles Henry.-Essay of a general method of chemical synthesis: experiments, by M. Raoul Pictet. On the fusion of carbonate of lime, by M. H. Le Chatelier. On the molecular weights of sodammonium and potassammonium, by M. A. Joannis.-On some crystallized sodium titanates, by M. H. Cormimbœuf.-On a propylamidophenol derived from camphor, by M. P. Cazeneuve.-On the colouring matter of the pollen, by MM. G. Bertrand and G. Poirault. On the manufacture of melanite garnet and spe by M. L. Michel.-On the rotating power of solutions, y Wyrouboff. Researches on the mode of elimination of car oxide, by M. L. de Saint-Martin.-Vital fermentations chemical fermentations, MM. Maurice Arthus and Ad Huber.-Remarks on the preceding communication, by Gautier.-Influence of the transfusion of blood from dogs, cinated against tuberculosis upon tuberculous infection, by J. Héricourt and Ch. Richet.-On a new species of ch genic bacteria, the Spirillum luteum, by M. Henri Jazee On two parasitic myzostomes of the Antedon phala (Müller), by M. Henri Prouho. BOOKS, PAMPHLETS, and SERIALS RECEIVE BOOKS.-Manners and Monuments of Prehistoric Peoples: M Nardaillac, translated by N. Bell (Putnam).-An Elementary Text. Hygiene H. R. Wakefield (Blackie)-More about Wild Na Brightwen (Unwin) -The Pharmacy and Poison Laws of the Kingdom (office of the Chemist and Druggist).—Lessons in re ary Algebra, 1st series: L. J. Pope (Bell).-The Visible Universe Gore (Lockwood).-Man and the Glacial Period: Dr G. F. W Paul).-Sinai from the Fourth Egyptian Dynasty to the Present Day Tide, 2nd edition: Sir R. S. Ball (S.P.C.K).-Les Races et les La H. S. Palmer, new edition, revised by Prof. Sayce (S. P.C. K.-I Prof. A. Lefèvre (Paris, Alcan).-A Contribution to our Kanakia Seedlings, 2 vols.: Sir John Lubbock (K. Paul).-Australasian New Directory, 3rd edition, 1892 (Gordon and Gotch)-Sultan to Sa French-Sheldon (Saxon). PAMPHLETS.-Recherches d'Optique Physiologique et Physique P.C. Royer (Bruxelles, Monnom).—Fauna Americana: D. T. de Ams (Madrid). SERIAL.-L'Anthropologie, tome iii. No. 4 (Paris, Masson. Parasitism of Volucella.-W. E. Hart. A Strange Commensalism-Sponge and Annelid.- Induction and Deduction.-E. E. Constance Jones The Late Prof. Tennant on Magic Mirrors.-Prof On a Supposed Law of Metazoan Development.–J. Experiments on Folding and on the Genesis A New Method of Treatment for Cholera Our Astronomical Column: The New Comet. Motion in the Line of Sight "Himmel und Erde " for November Geographical Notes Stromboli in 1891. By L. W. Fulcher A Large Meteorite from Western Australia. trated.) By James R. Gregory The Cross-Striping of Muscle. Iridescent Colours. By Alex. Hodgkinson. Societies and Academies Books, Pamphlets, and Serials Received DIARY OF SOCIETIES. LONDON. THURSDAY, NOVEMBER 24. YAL SOCIETY, at 4.50.-Ionic Velocities: W. C. Dampier Whetham.The Theory of the Compositions of Numbers: Major MacMahon. VAL GEOGRAPHICAL SOCIETY (at Burlington Gardens). at 8.30.Journey from the East Coast to Uganda and the Great Equatorial Fakes of Africa: Captain F. D. Lugard. TITUTION OF ELECTRICAL ENGINEERS, at 8.-Experimental Researches in Alternate-Current Transformers: Prof. J. A. Fleming, F.R.S. STITUTION OF CIVIL ENGINEERS, at 2.30.-Students' Visits to the Gas Hight and Coke Company's Chief Office, Horseferry Road, Westminster. NDON INSTITUTION, at 6.-The Ruined Cities of Mashonaland (Illus. rated): J. Theodore Bent. FRIDAY, NOVEMBER 25. YSICAL SOCIETY, at 5.-Experiments in Electric and Magnetic Fields, Constant and Varying: E. C. Rimington and E. Wythe Smith. SUNDAY, NOVEMBER 27. 'NDAY LECTURE SOCIETY, at 4-Symbiosis-a Story of Plant Parasites and Messmates (with Oxy-hydrogen Lantern Illustrations): Prof. H. Marshall Ward, F.R.S. MONDAY, NOVEMBER 28. OYAL GEOGRAPHICAL SOCIETY, at 8.30: To Lake Bangweolo and the ONDON INSTITUTION, at 5.-Curiosities of Bird Life (Illustrated): Dr. R. TUESDAY, NOVEMBER 29. STITUTION OF CIVIL ENGINEERS, at 8.-The Manufacture of Small Arms: John Rigby. WEDNESDAY, NOVEMBER 30. OVAL MICROSCOPICAL SOCIETY, at 8.-Conversazione. THURSDAY, DECEMBER 1. NNEAN SOCIETY, at 8.-Notes on (Ecodoma cephalotes and the Fungi it Cultivates: J. H. Hart.-On a Small Collection of Crinoids from the Sahul Bank, North Australia: Prof. F. Jeffrey Bell.-Descriptions of Twenty-six New Species of Land Shells from Borneo: E. A. Smith. RMICAL SOCIETY, at 8-On the Formation of Orcinol and other Condensation Products from Dehydracetic Acid J. Norman Collie.-Isolaion of Two Predicted Hydrates of Nitric Acid: S. U. Pickering.-Anydrous Oxalic Acid: W. W. Fisher.-Observations on the Origin of Colour and of Fluorescence: W. N. Hartley.-The Origin of Colour-Azobenzene: H. E. Armstrong.-The Reduction Products of aa' dimethyl a' diacetylpentane: Dr. Kipping.-The Products of the Action of ulphuric Acid on Camphor: Drs. Armstrong and Kipping.-Methods or Showing the Spectra of easily Volatile Metals and their Salts, and of eparating their Spectra from those of the Alkaline Earths: W. N Martley. IDON INSTITUTION, at 6.-Photographs of Flying Bullets, &c. (Illusated): Prof. C. V. Boys, F.R.S. NEWTON'S ELECTRIC LANTERNS, Sngle, Double and Triple, as made for the Royal Institution of Great Britain, the Royal Dublin Society, Oxford and Cambridge Universities, &c. NEWTON'S NEW PATENT TRIPLE ROTATING ELECTRIC LANTERN. The Author of " Optical Projection" says of this Lantern :-"The most complete, convenient, and powerful instrument for scientific demonstration with which I am acquainted.' The Author of "The Book of the Lantern" says:-"The most complete and perfect projection apparatus ever devised." ELECTRIC MICROSCOPES FOR PROJECTION. OPTICAL LANTERNS AND SLIDES Twelve New Sets of Agricultural Slides for Technical Education-Injurious SCIENTIFIC AND PHYSICAL APPARATUS OF EVERY DESCRIPTION. Catalogue, 144 pages, 6d. NEWTON & CO., Manufacturing Opticians to the Queen and the Government, To the Royal Institution of Great Britain and the Science and Art 3 FLEET STREET, LONDON. WIMSHURST MACHINES. With Glass Plates, all sizes, double and multiple also with Ebonite Cylinders with and without Glass Cases. Batteries, galvanic and medical, Telephones. Galvanometers, pocket, lecture-table and laboratory. School Apparatus of every description. LARGE CATALOGUE, Fifth Edition, Royal 8vo, 144 pp., 700 Illustrations, Post free, 7d. KING, MENDHAM, & Co., Western Electrical Works, Bristol. London Address: 12 FENCHURCH STREET, E. C. (W. B. ALLISON, AGENT.) ESTABLISHED 1876. STANLEY Mathematical Instrument Manufacturer to H.M. Government, Council of India, Science and Art Department, Admiralty, &c. Mathematical, Drawing, and Surveying Instruments of every description. Of the Highest Quality and Finish, at the most Moderate Prices. Illustrated Price List Post Free. W. F. S. obtained the only Medal in the Great Exhibition of 1862 for Excellence of Construction of Mathematical Instruments, and the only GOLD MEDAL in the International Inventions Exhibition 1885 for Mathematical Work. Silver Medal, Architects' Exhibition, 1886. Address:-GREAT TURNSTILE, HOLBORN, LONDON, W.C. Instrument Company, Cambridge. Address all communications "Instrument Company, Cambridge." Price List of Scientific Instruments, sent post free. Illustrated Descriptive List sent on receipt of Is. 6d. The Cambridge Scientific Instrument Company, St. Tibb's Row, Cambridge. TO SCIENCE LECTURERS. See Mr. HUGHES'S PATENT COMBINATION OPTICAL LANTERN, used by late W. LANT CARPENTER, Esq., Prof. FORBES. New Triple constructed for B. J. MALDEN, Esq., this season. New Oxyhydrogen Microscope. Grand Results. Docwra Triple, Prize Medal, Highest Award. Supplied to the Royal Polytechnic Institution, Dr. H. GRATTAN GUINNESS, Madame ADELINA PATTI, &c. Patent Pamphagos Lantern Science Lecture Sets. Novelties Cheapest and Best. Elaborately Illustrated Catalogue 300 pages, 15.; Postage, 5d. Smaller do., 6d. Pamphlets Free.-HUGHES, SPECIALIST, Brewster House, Mortimer Road, Kingsland, N. |