sweeping ephemerides for the whole year were published from Strassburg some time since, and will be found in the Vierteljahrsschrift der Astronomischen Gesellschaft, Jahrgang 12. Those given above apply to greater distance from perihelion.

THE TRANSIT of Venus, 1882.-At the sitting of the Paris Academy of Sciences, on the 2nd inst., the Minister of Foreign Affairs transmitted a letter from the British Ambassador, on the part of his Government, desiring to be informed with which French authorities the Royal Society of London should communicate, with the view to an interchange of opinions relative to the observation of the approaching transit of Venus. The letter was referred to a commission already nominated.

COMET 1880, V. (PECHÜLE, DECEMBER 16).-This comet was followed by M. Bigourdan until March 31, efforts having been made at the Observatory of Paris to observe it as long as possible on account of the resemblance of the orbit to that of the great comet of 1807. M. Bigourdan's last elements gave the place with errors of only 25. o in right ascension, and 20" in declination: they will be found in Comptes rendus, vol. xcii.

IN the American Chemical Journal Prof. Mallet describes a simple form of calorimeter whereby the specific heats of moderately small quantities of solids or liquids may be measured with a fair degree of accuracy. Mercury is employed, instead of water, as the material whose temperature is raised, and comparison is made, not of the total amounts of heat given out by different bodies on cooling, but of fractions of this heat rendered as nearly as possible equal.

IN Compt. rend. Berthelot gives several thermal measurements showing that in the substitution of halogens for hyd ogen in hydrocarbons, the quantity of heat evolved varies according to the series and chemical function of the hydrocarbons employed, and is generally smaller the greater the number of halogen atoms substituted. The heat of formation of chloral alcoholate in various physical states is also considered by Berthelot : among other results it is shown that chloral hydrate is decomposed by an excess of absolute alcohol, but that the alcoholate is decomposed by much water; in the former of these actions there is exhibited

A SERIES of optically active amylamines is described in Compt. rend. by M. Plimpton. These compounds are obtained from amyl bromide-from active amylic alcohol-by the action of alcoholic ammonia.

IN Chem. Centralblatt E. Ludwig describes experiments on the localisation of arsenic, absorbed as arsenious oxide, in the animal organis.n contrary to the results of many former experimenters, Ludwig asserts that an accumulation of arsenic occurs in the liver: neither the bones nor the brain retain arsenic for any length of time. Arsenic was detected in the liver of a dog forty days after the last dose had been administered, but no trace could be found in the brain, bones, or muscles. Ludwig's results are generally confirmed by Johnson and Chittenden (Amer. Chem. Journ.).

MM. DES CLOIZEAUX AND DAMOUR describe (Compt. rend.) a new selenite of copper, to which they give the name Chalcomenite. The mineral occurs in the Argentine Republic, in s nall green clinorhombic crystals, associated with selenite of lead, and selenite of lead and copper.

M. SULLIOT proposes (Compt. rend.) to employ "chamber crystals" as a disinfectant. He places a solution of these crystals in sulphuric acid in the room or other place to be disinfected; the atmospheric moisture slowly decomposes the liquid with liberation of oxides of nitrogen, which destroy noxious organic matter present in the air.

MR. M. W. WILLIAMS describes, in Chem. Soc. Journal, a method for freeing water, to be analysed by the process of Frankland and Armstrong, from nitrates and ammonia. He digests the water with carefully-prepared "copper-zinc couple," whereby all nitrates are reduced to ammonia; he then distils off ammonia, evaporates to dryness, and proceeds in the usual manner. The use of sulphurous acid, which has always been much objected to, is thus obviated.

IN the same journal there is a suggestive paper by Prof. Hartley on the "Relation between the molecular structure of carbon compounds and their absorption-spectra." Evidence is accumulated in favour of the view that the selective absorption exhibited by "aromatic" compounds depends on the vibrations of the carbon atoms within the molecule, but that these atomic vibrations are dependent upon the nature of the molecular vibrations themselves, and are probably to be regarded as harmonics of these fundamental vibrations.

THE second and third parts of the Gazetta Chimica Italiana for the present year exhibit very unmistakably the activity of Italian chemists, chiefly in the domain of organic chemistry. Schiff continues his researches on Glucosides; the derivatives of thymol are studied by Paternò and Canzoneri; Macagno describes experiments on the spectroscopic detection of artificial and other known chemists contribute papers.

-and formation of a less volatile-chloral alcoholate; and at the same time the expulsion of a less volatile substance-waterby a more volatile-alcohol.

THE proto-salts of chromium (or chromous salts) are unstable and but little known: in Compt. rend. M. Moissau describes two salts belonging to this series, viz., chromous chloride, CrCl, and chromous sulphate, CrSO47H2O.

IN the Berichte of the Ger nan Chemical Society Herr C. Zi nmermann states that potassium permanganate may be used for determining iron in presence of considerable quantities of hydrochloric acid, if a solution of manganous chloride, or preferably manganous sulphate, be added previous to titration. ACCORDING to the hypothesis of Vant' Hoff, propyl glycol ought to be an optically active liquid, inasmuch as the molecule of this compound contain; one asymmetric carbon aton, i.e. an atom directly united with four different radicles;-propyl CH-C-CH2OH glycol being formulated as

H он

Le Bel

has recently shown (Compt. rend.) that if ordinary propyl glycol-from glyceric acid-be subjected to partial fermentation, the unfermented residue exhibits slight dextrorotatory powers. Le Bel thinks that ordinary propyl glycol contains both an optically active and an optically inactive modification, and that the latter being decomposed by the ferment, the presence of the former is rendered evident. From optically active propyl glycol Le Bel has prepared an active propylene oxi le boiling at 35%, which he states is the most volatile optically active compound at present known.

GEOGRAPHICAL NOTES

MR. EDWARD WHYMPER on Monday last addressed a large meeting of the Geographical Society on some features in his recent journey among the Great Andes of the Equator. His paper was not, however, of so popular a nature as those which he read before the Alpine Club and the Society of Arts. The chief facts left on the minds of his very attentive audience may be briefly stated. Mr. Whymper found by careful experiments that aneroid barometers are not to be depended upon for the determination of heights, and that there is a remarkable differ. ence in altitudes as fixed by the boiling point of water and the mercurial barometer. He asserted, as the result of his observations, that it is a mistake to suppose that there are two parallel chains in the Ecuadorian Andes, as usually shown on our map. This is a point, however, on which more light is evidently required. Mr. Whymper's account of his ascent of the hitherto unknown peak called Sara-Urcu, was very interesting, and this achievement alone would stamp him a mou itaineer of the highest skill and courage.

THE following award has just been made of the medals given annually by the Council of the Geographical Society for com petition among a limited number of public schools:-Physical Geography (Mr. H. N. Moseley, F.R.S., examiner): Gold medal, E. G. Reid, Dulwich College; silver medal, Sydney Edkins, City of London School; Political Geography (Right Rev. Bishop Abraham, examiner): Gold medal, Theodore

THE Willem Barents, the little Polar ship which has already made three voyages to the Northern Polar Sea, has left Amsterdam for the fourth time. The crew consists of a lieutenant of the Royal Navy, H. van Broekhuyzen, as captain, two other officers, a physician, a zoologist, a photographer (the Englishman, Mr. Grant), and six sailors.

DOCTORS ARTHUR AND AUREL KRAUSE have left Bremen to spend some time in the neighbourhood of Behring Straits for the purpose of exploring and collecting, at the expense of the Bremen Geographical Society. They will visit the Chukchi peninsula, Behring Islands, and Alaska, where they will make zoological collections and carry on various scientific observations.

MR. HENRY SOLTAU and Mr. J. W. Stevenson, of the China Inland Mission, have successfully made the journey from Bhamo into China, reaching I-chan-fu, on the Yang-tsze-kiang, on March 14. This is the first time that it has been accomplished by Europeans, and the time occupied was about four months.

THE first paper in the May number of Petermann's Mittheilungen is a study of the Padolian Dniester region by Ritter v. Habdank Dumkowski. This is followed by the continuation of Dr. Radde's account of his journey to Talysh, Aderbeijan and the Sawalan; M. Charray's expedition to Central America from the North American Review; M. Potanin's researches in Western Mongolia in 1876-77, with a map; Recent Surveys in the Western United States, with a map; and the usual Monthly Notes. Among the latter is a long account of Dr. Lenz's journey to Timbuctoo, with a sketch-map.

WE have received Nos. 1 and 3 of the Bulletin of the American Geographical Society, the two most important papers in which are on the recent investigations of the Gulf Stream, by the U.S. Coast Survey steamer Blake, by Commander J. R. Bartlett, and Changes in the Physical Geography of the Ancient Home of Man in Central and Western Asia, by the Rev. Owen Street.

DR. MOFFAT, the venerable missionary and pioneer explorer in Africa, was entertained at a banquet in the Mansion House on Saturday.

THE Bulletin of the Society of Commercial Geography of Bordeaux contains a brief statement of M. Paul Soleillet's views on the African question. After addressing the Society M. Soleillet proceeded to Paris, but he entertains hopes of being able to return to West Africa in November.

THE PRODUCTION OF SOUND BY RADIANT ENERGY 1

IN my Boston paper on the photophone (NATURE, vol. xxii. p. 500) the discovery was announced that thin disks of very many different substances emitted sounds when exposed to the action of a rapidly-interrupted beam of sunlight. The great variety of material used in these experiments led me to believe that sonorousness under such circumstances would be found to be a general property of all matter.

At that time we had failed to obtain audible effects from masses of the various substances which became sonorous in the condition of thin diaphragms, but this failure was explained upon the supposition that the molecular disturbance produced by the light was chiefly a surface action, and that under the circumstances of the experiments the vibration had to be transmitted through the mass of the substance in order to affect the ear. It was therefore supposed that if we could lead to the ear air that was directly in contact with the illuminated surface, louder sounds might be obtained, and solid masses be found to be as sonorous as thin diaphragms. The first experiments made to verify this hypothesis pointed towards success. A beam of unlight was focussed into one end of an open tube, the ear being placed at the other end. Upon interrupting the beam, a clear musical tone was heard, the pitch of which depended upon the frequency of the interruption of the light and the loudness upon the material composing the tube.

While in Paris a new form of the experiment occurred to my mind, which would not only enable us to investigate the sounds produced by masses, but would also permit us to test the more Abstract of a paper by Prof. Alexander Graham Bell, read before the National Academy of Arts and Sciences, April 21, 1881.

intermittent light, is a property common to all matter. The substance to be tested was to be placed in the interior of a transparent vessel made of some material which (like glass) is transparent to light but practically opaque to sound.

Under such circumstances the light could get in, but the sound produced by the vibration of the substance could not get out. The audible effects could be studied by placing the ear in communication with the interior of the vessel by means of a hearing tube.

Some preliminary experiments were made in Paris to test this idea, and the results were so promising that they were communicated to the French Academy on October 11, 1880, in a note read for me by Mr. Antoine Breguet.

I wrote to Mr. Tainter suggesting certain experiments, and upon my return to Washington in the early part of January, Mr. Tainter communicated to me the results of the experiments he had made in my laboratory during my absence in Europe. He had commenced by examining the sonorous properties of a vast number of sul stances inclosed in test-tubes in a simple empirical search for loud effects. He was thus led gradually to the discovery that cctton-wool, worsted, silk, and fibrous materials generally, produced much louder sounds than hard rigid bodies like crystals, or diaphragms such as we had hitherto used.

In order to study the effects under better circumstances he inclosed his materials in a conical cavity in a piece of brass closed by a flat plate of glass. A brass tube leading into the cavity served for connection with the hearing-tube. When this conical cavity was stuffed with worsted or other fibrous materials the sounds produced were much louder than when a test-tube was employed. Mr. Tainter next collected silks and worsteds of different colours, and speedily found that the darkest shades produced the best effects. Black worsted especially gave an extremely loud sound.

About a teaspoonful of lamp-black was placed in a test-tube and exposed to an intermittent beam of sun-light. The sound produced was much louder than any heard before. Upon smoking a piece of plate-glass, and holding it in the intermittent beam with the lamp-black surface towards the sun, the sound produced was loud enough to be heard, with attention, in any part of the room. With the lamp-black surface turned from the sun the sound was much feebler.

Upon smoking the interior of the conical cavity and then exposing it to the intermittent beam with the glass lid in position as shown, the effect was perfectly startling. The sound was so loud as to be actually painful to an ear placed closely against the end of the hearing-tube. The sounds, however, were sensibly louder when we placed some smoked wire gauze in the receiver.

When the beam was thrown into a resonator, the interior of which had been smoked over a lamp, most curious alternations of sound and silence were observed. The interrupting disk was set rotating at a high rate of speed, and was then allowed to come gradually to rest. An extremely feeble musical tone was at first heard, which gradually fell in pitch as the rate of interruption grew less. The loudness of the sound produced varied in the most interesting manner. Minor reinforcements were constantly occurring, which became more and more marked as the true pitch of the resonator was neared. When at last the frequency of interruption corresponded to the frequency of the fundamental of the resonator, the sound produced was so loud that it might have been heard by an audience of hundreds of people.

The extremely loud sounds produced from lamp-black have enabled us to demonstrate the feasibility of using this substance in an articulating photophone in place of the electrical receiver formerly employed. Words and sentences spoken into the transmitter in a low tone of voice were audibly reproduced by the lamp-black receiver at forty metres distance.

In regard to the sensitive materials that can be employed, our experiments indicate that in the case of solids the physical condition and the colour are two conditions that markedly influence the intensity of the sonorous effects. The loudest sounds are produced from substances in a loose, porous, spongy condition, and from those that have the darkest or most absorbent colours. The materials from which the best effects have been produced are cotton-wool, worsted, fibrous materials generally, cork, sponge, platinum and other metals in a spongy condition, and lamp black.

The loud sounds produced from such substances may perhaps be explained in the following manner: Let us consider, for

example, the case of lamp-black-a substance which becomes cheated by exposure to rays of all refrangibility. I look upon a mass of this substance as a sort of sponge, with its pores filled 6 with air instead of water. When a beam of sunlight falls upon this mass the particles of lamp-black are heated, and consequently = expand, causing a contraction of the air-spaces or pores among them. Under these circumstances a pulse of air should be expelled, just as we would squeeze out water from a sponge. The force with which the air is expelled must be greatly increased by the expansion of the air itself, due to contact with the heated particles of lamp-black. When the light is cut off the converse process takes place. The lamp-black particles cool and contract, thus enlarging the air-spaces among them, and the inclosed air also becomes cool. Under these circumstances a partial vacuum should be formed among the particles, and the outside air would then be absorbed as water is by a sponge when the pressure of the hand is removed.

I imagine that in some such manner as this a wave of condensation is started in the atmosphere each time a beam of sunlight falls upon lamp-black, and a wave of rarefaction is originated when the light is cut off. We can thus understand how it is that a substance like lamp-black produces intense sonorous vibrations in the surrounding air, while at the same cime it communicates a very feeble vibration to the diaphragm or solid bed upon which it rests.

In his paper read before the Royal Society on March 10 Mr. Preece describes experiments from which he claims to have proved that the effects are wholly due to the vibrations of the confined air, and that the disks do not vibrate at all.

But for reasons stated Mr. Bell concludes that in the case of thin disks a real vibration of the diaphragm is caused by the action of the intermittent beam, independently of any expansion and contraction of the air confined in the cavity behind the diaphragm. Lord Rayleigh has shown mathematically that a to-and-fro vibration, of sufficient amplitude to produce an audible sound, would result from a periodical communication and abstraction of heat, and he says: "We may conclude, I think, that there is at present no reason for discarding the obvious explanation that the sounds in question are due to the bending of the plates under unequal heating" (NATURE, vol. xxiii. p. 274).

[Mr. Bell then describes experiments (devised by Mr. Tainter) which have given results decidedly more favourable, in his opinion, to the theory of Lord Rayleigh than to that of Mr. Preece.]

The list of solid substances that have been submitted to experiment in my laboratory is too long to be quoted here, and I shall merely say that we have not yet found one solid body that has failed to become sonorous under proper conditions of experiment.1

The sounds produced by liquids are much more difficult to observe than those produced by solids. The high absorptive power possessed by most liquids would lead one to expect intense vibrations from the action of intermittent light, but the number of sonorous liquids that have so far been found is extremely limited, and the sounds produced are so feeble as to be heard only by the greatest attention and under the best circumstances of experiment. In the experiments made in my laboratory a very long test tube was filled with the liquid under examination, and a flexible rubber-tube was slipped over the mouth far enough down to prevent the possibility of any light reaching the vapour above the surface. Precautions were also taken to prevent reflection from the bottom of the test-tube. An intermittent beam of sunlight was then focussed upon the liquid in the middle portion of the test-tube by means of a lens of large diameter.

Acoustic vibrations are always much enfeebled in passing from liquids to gases, and it is probable that a form of experi ment may be devised which will yield better results by communicating the vibrations of the liquid to the air through the medium of a solid rod.

The vapours of the following substances were found to be highly sonorous in the intermittent beam:-Water vapour, coal gas, sulphuric ether, alcohol, ammonia, amylene, ethyl bromide, diethylamene, mercury, iodine, and peroxide of nitrogen. The loudest sounds were obtained from iodine and peroxide of nitrogen. I have now shown that sounds are produced by the direct action of intermittent sunlight from substances in every physical condition (solid, liquid, and gaseous), and the probability is therefore very greatly increased that sonorousness under such circumstances will be found to be a universal property of matter.

At the time of my communication to the American Association the loudest effects obtained were produced by the use of selenium, arranged in a cell of suitable construction and placed in a galvanic circuit with a telephone. But the selenium was very inconstant in its action, and from experiments by Dr. Chichester Bell of University College of London, it was found that all the selenium used was tainted with impurities.

Prof. W. G. Adams (Proceedings Royal Society, vol. xxiv. p. 163) has shown that tellurium, like selenium, has its electrical resistance affected by light, and we have found that when this tellurium spiral is connected in circuit with a galvanic battery and telephone and exposed to the action of an intermittent beam of sunlight, a distinct musical tone is produced by the telephone. It occurred to Mr. Tainter before my return to Washington last January that the very great molecular disturbance produced in lamp-black by the action of intermittent sunlight should produce a corresponding disturbance in an electric current passed through it, in which case lamp-black could be employed in place of selenium in an electrical receiver. This has turned out to be the case, and the importance of the discovery is very great, especially when we consider the expense of such rare substances as selenium and tellurium.

We have observed that different substances produce sounds of very different intensities under similar circumstances of experiment, and it has appeared to us that very valuable information might be obtained if we could measure the audible effects produced. For this purpose we have constructed several different forms of apparatus for studying the effects, but our researches are not yet complete. When a beam of light is brought to a focus by means of a lens the beam diverging from the focal point becomes weaker as the distance increases in a calculable degree. Hence if we can determine the distances from the focal point at which two different substances emit sounds of equal intensity we can calculate their relative sonorous powers. liminary experiments were made by Mr. Tainter during my absence in Europe to ascertain the distance from the focal point of a lens at which the sound produced by a substance became inaudible. A few of the results obtained will show the enormous differences existing between different substances in this respect. Distance from Focal Point of Lens at which Sounds become Inaudible with Different Substances

...

Pre

m.

1'51 I'90 2'00

2'15 2'15

3'10

4'01

4'06

4'13 4'38

Yellow worsted

Yellow silk

White cotton-wool

Green silk

4°52

Blue worsted

4.69

Purple silk

4.82

Brown silk

The meaning we have uniformly attached to the words "photophone" and "light" will be obvious from the following passage quoted from my Boston paper :

"Although effects are produced as above shown by forms of radiant energy, which are invisible, we have named the apparatus for the production and reproduction of sound in this way the 'photophone,' because an ordinary beam of light contains the rays which are operative."

To avoid in future any misunderstandings upon this point we have decided to adopt the term "radiophone" proposed by M. Mercadier as a general term signifying an apparatus for the production of sound by any form of radiant energy, limiting the words thermophone, photophone, and actinophone to apparatus for the production of sound by thermal, luminous, or actinic rays respectively. M. Mercadier, in the course of his researches in radiophony, passed an intermittent beam from an electric lamp through a prism, and then examined the audible effects produced in different parts of the spectrum (Comptes rendus, December 6, 1880). We have repeated this experiment, using the sun as our source of radiation, and have obtained results somewhat different from those noted by M. Mercadier. A beam of sunlight was reflected from a heliostat through an achromatic lens, so as to form an image of the sun upon the slit. The beam then passed through another achromatic lens and through a bisulphide of carbon prism, forming a spectrum of great intensity, which, when focussed upon a screen, was found to be sufficiently pure to show the principal absorption lines of the solar spectrum. The disk-interruj ter was then turned with sufficient rapidity to produce from five to six hundred interruptions of the light per second, and the spectrum was explored with the receiver, which was so arranged that the lamp-black surface exposed was limited by a slit, as shown.

Under these circumstances sounds were obtained in every part of the visible spectrum, excepting the extreme half of the violet, as well as in the ultra-red. A continuous increase in the loudness of the sound was observed upon moving the receiver gradually from the violet into the ultra-red. The point of maximum sound lay very far out in the ultra-red. Beyond this point the sound began to decrease, and then stopped so suddenly that a very slight motion of the receiver made all the difference between almost maximum sound and complete silence.

2. The lamp-blacked wire gauze was then removed and the interior of the receiver was filled with red worsted. Upon exploring the spectrum as before, entirely different results were obtained. The maximum effect was produced in the green at that part where the red worsted appeared to be black, On either side of this point the sound gradually died away, becoming inaudible on the one side in the middle of the indigo, and on the other at a short distance outside the edge of the red.

3. Upon substituting green silk for red worsted the limits of audition appeared to be the middle of the blue and a point a short distance out in the ultra-red. Maximum in the red.

4. Some hard-rubber shavings were now placed in the receiver. The limits of audibility appeared to be on the one band the junction of the green and blue, and on the other the outside edge of the red. Maximum in the yellow. Mr. Tainter thought he could hear a little way into the ultra-red, and to his ear the maximum was about the junction of the red and orange.

5. A test-tube containing the vapour of sulphuric ether was then substituted for the receiver. Commencing at the violet end, the test-tube was gradually moved down the spectrum and out into the ultra-red without audible effect, but when a certain point far out in the ultra-red was reached a distinct musical tone suddenly made its appearance, which di appeared as suddenly on moving the test-tube a very little further on.

6. Upon exploring the spectrum with a test-tube containing the vapour of iodine the limits of audibility appeared to be the middle of the red and the junction of the blue and indigo. Maximum in the green.

7. A test-tube containing peroxide of nitrogen was substituted for that containing ic dine. Distinct sounds were obtained in all parts of the visible spectrum, ut no sounds were observed in the ultra-red.

The maximum effect seemed to me to be in the blue. The sounds were well-marked in all parts of the violet, and I even fancied that the audi le effect extended a little way into the

the absorption-spectrum of peroxide of nitrogen it was at once observed that the maximum sound was produced in that part of the spectrum where the greatest number of absorption lines made their appearance.

8. The spectrum was now explored by a selenium cell, and the audible effects were observed by means of a telephone in the same galvanic circuit with the cell. The maximum effect was produced in the red. The audible effect extended a little way into the ultra-red on the one hand and up as high as the middle of the violet on the other.

Although the experiments so far made can only be considered as preliminary to others of a more refined nature, I think we are warranted in concluding that the nature of the rays that produce sonorcus effects in different substances depends upon the nature of the substances that are exposed to the beam, and that the sounds are in every case due to those rays of the spectrum that are absorbed by the body.

Our experiments upon the range of audibility of different substances in the spectrum have led us to the construction of a new instrument for use in spectrum analysis. The eye-piece of a spectroscope is removed, and sensitive substances are placed in the focal point of the instrument behind an opaque diaphragm containing a slit. These substances are put in communication with the ear by means of a hearing-tube, and thus the instrument is converted into a veritable "spectrophone."

Suppose we smoke the interior of our spectrophonic receiver, and fill the cavity with peroxide of nitrogen gas. We have then a combination that gives us good sounds in all parts of the spectrum (visible and invisible) except the ultra violet. Now pass a rapidly interrupted beam of light through some substance whose absorption spectrum is to be investigated, and bands of sound and silence are observed upon exploring the spectrum, the silent positions corresponding to the absorption bands. Of course the ear cannot for one moment compete with the eye in the examination of the visible part of the spectrum; but in the invisible part beyond the red, where the eye is useless, the ear is invaluable. In working in this region of the spectrum lamp. black alone may be used in the spectrophonic receiver. Indeed the sounds produced by this substance in the ultra-red are so well marked as to constitute our instrument a most reliable and convenient substitute for the thermo-pile. A few experiments that have been made may be interesting.

1. The interrupted beam was filtered through a saturated solution of alum.

Result: The range of audibility in the ultra-red was slightly reduced by the absorption of a narrow band of the rays of lowest refrangibility. The sounds in the visible part of the spectrum seemed to be unaffected.

2. A thin sheet of hard rubber was interposed in the path of the beam.

Result Well-marked sounds in every part of the ultra-red. No sounds in the visible part of the spectrum, excepting the extreme half of the red.

The e experiments reveal the cause of the curious fact allı ded to in my paper read before the American Association last August-that sourds were heard from selenium when the beam was filtered through both hard rubber and alum at the same time.

3. A solution of ammonia-sulphate of copper was tried.

Result: When placed in the path of the beam the spectrum disappeared, with the exception of the blue and violet end. To the eye the spectrum was thus reduced to a single broad band of blue-violet light. To the ear however the spectrum revealed itself as two bands of sound with a broad space of silence between. The invisible rays transmitted constituted a narrow band just outside the red.

I think I have said enough to convince you of the value of this new method of examination, but I do not wish you to understand that we look upon our results as by any means complete. It is often more interesting to observe the first totterings of a child than to watch the firm tread of a full-grown man, and I feel that our first footsteps in this new field of science may have more of interest to you than the fuller results of mature research. This nut be my excuse for having dwelt so long upon the details of incom; lete experiments.

I recognise the fact that the spectrophone must ever remain a mere adjunct to the spectroscope, but I anticipate that it has a wide and independent field of usefulness in the investigation of absorption spectra in the ultra-red.

ON AN ACOUSTIC PHENOMENON NOTICED IN A CROOKES TUBE

A

SHORT time since, while experimenting with a Crookes tube, I noticed a phenomenon which was quite striking, and so evident that it hardly seems possible that it has not frequently been observed before; but as no allusion to the effect in question has come to my notice, I venture to call attention to it.

In working with the tube in which a piece of sheet platinum is rendered incandescent by the concentration upon it of electrified particles, repelled from a concave mirror, I noticed that when the mirror was made the negative electrode, so that this concentration took place, a clear and quite musical note issued from the tube. I thought at first that the pitch of the note would coincide with that produced by the circuit-breaker used with the coil (which made about 100 breaks per second), but this did not prove to be the case. In fact very great changes in the rate of the circuit-breaker did not affect the note given by the tube. The effect seemed to be produced by the vibration of the sheet-platinum in its own period, under the influence of the molecular impact, which vibration was communicated to the glass walls of the tube by the enamel rod to which the platinum was attached, giving rise to a sound somewhat resembling the pattering of rain against a window-pane, but higher in pitch and more musical. This sound changed its character very greatly when the direction of the current was reversed, a feeble murmur only being heard. I obtained a similar musical note, though far less loud, with the "mean free-path tube," best when the middle plate was positive. With a tube containing phosphorescent sulphide of calcium, the note was very dull in its quality and low in pitch, but still quite perceptible. With this tube a change in the direction of the current, as might be expected, did not affect the sound produced. I did not obtain this musical note from any tube that I have in which the current enters and leaves by a straight wire, except in the case of a single Geissler's tube exhausted so as to give stratifications, in which it was very feebly heard.

UNIVERSITY AND EDUCATIONAL

INTELLIGENCE

LARGE number of ladies and gentlemen assembled on Tuesday in Cowper Street to witness the laying of the foundation-stone of the Finsbury Technical College which it has lately been resolved to establish by the City and Guilds of London Institute, by His Royal Highness Prince Leopold. According to the report of the Council of the Institute to the Governors, the projected building is estimated to cost 20,382/., exclusive of the professional charges, fittings, and other incidental expenses, which will amount to some 5000l. In the plans ample accom. modation is provided for instruction in the application of physics, chemistry, and mechanics to the various industries. The building will contain thirty-two rooms, including a large laboratory, two lecture theatres, class, drawing, private, and engine rooms, workshops, and clerks' offices. Lord Selborne, in welcoming the Prince, after noting the progress of science as applied to arts and manufactures in this and other countries, said that in the race of competition the prize must in the end belong to those who best knew how to build the superstructure of arts and manufacture on their handicrafts with a sound foundation of scientific knowledge. The ceremony of laying the stone was gone through by Prince Leopold, who in the course of his remarks said that the institution has proclaimed its determination to enter into generous rivalry with other countries in those branches of trade and commerce in which, one must needs confess, our native industries have of late years not taken that position which we as Englishmen would wish them to occupy. We are beginning to realise that a thorough and liberal system of education must be placed within the reach of the British artisan in order to enable him to hold his own against foreign competition. Mr. Mundella said that by instituting this college they were taking the same step in applying science to industries which had been taken in applying arts to manufactures at South Kensington. Among the articles deposited in the cavity of the foundation-stone was a copy of NATURE.

Read by C. R. Cross at a meeting of the American Academy of Arts and Sciences, November 10, 1880.

THE Berlin correspondent of the Times states that a movement is afoot among the Germans in the United States for the creation of a native University on the model of those in the old country, to be called the Kaiser Wilhelm Universität, in commemoration of the "glorious resuscitation of the Fatherland." Milwaukee is mentioned as the likeliest candidate among all the cities of the West that aspire to the honour of harbouring this plant of pure Teutonic culture, which would cost, to begin with, about two million dollars. It is not at all probable, however, that the scheme will come to anything.

SCIENTIFIC SERIALS

(vol. xv. part 3), contains :-On the bones, articulations, and THE Journal of Anatomy and Physiology for April, 1881 muscles of the rudimentary hind-limb of the Greenland right whale (Balana mysticetus), by Dr. J. Struthers.-On the stridulating apparatus of Callomystax gagata, by Prof. A. C. Haddon (Plate 20). On the sternum as an index of age and sex, by Dr. Thomas Dwight (concludes that the breast-bone is no trustworthy guide either to the sex or the age).-On the mechanism of costal respiration, by Dr. J. M. Hobson (with figures).-On the membrana propria of the mammary gland, by Dr. C. W. M. Moullin (with figures).-On double and treble staining of microscopical specimens, by Dr. W. Stirling.-On the comparative anatomy of the lymphatics of the mammalian urinary bladder, by Drs. George and F. Elizabeth Hoggan (plate 21).-Notes on a dissection of a case of epispadias, and on the morphology of the muscles of the tongue and pharynx, by Dr. R. J. Anderson. -On the so-called movements of pronation and supination in the hind-limb of certain marsupials, by Dr. A. H. Young.-A contribution to the pathological anatomy of pneumonokoniosis (Chalicosis pulmonum), by Thos. Harris (plate 22).—On the histology of some of the rarer forms of malignant bone tumours, by Robt. Maguire.—On the morbid histology of the liver in acute yellow atrophy, by Prof. Dreschfeld.—On the relationship between the muscle and its contraction, by Dr. J. Theodore Cash. -Anatomical notes.

The Quarterly Journal of Microscopical Science, April, 1881, contains-On the minute anatomy of the branchiate echino. derms, by P. Herbert Carpenter (plates II and 12).-On young stages of Limnocodium and Geryonia (plate 13), and observations and reflections on the appendages and on the nervous system of Apus cancriformis, by E. Ray Lankester (plate 20).— On the origin and significance of the metamorphosis of Actinotrocha, by Edmund B. Wilson (plates 14 and 15).-A further contribution to the minute anatomy of the organ of Jacobson in the guinea-pig (plates 16 and 17), and histological notes, by Dr. E. Klein. On the development of microscopic organisms occurring in the intestinal canal, by Dr. D. Cunningham (plate 18).-Researches upon the development of starch-grains, by A. F. W. Schimper (plate 19), translated from the Botanische Zeitung.— On the cause of the striation of voluntary muscular tissue, by Dr. J. B. Haycraft.-On the relation of micro-organisms to disease, by Prof. Lister; with notes and memoranda.

The American Naturalist, April, 1881.-Wm. Trelease, on the fertilisation of Salvia splendens by birds. (The fertilisation is apparently effected by a humming-bird.)—Prof. E. D. Cope, on the origin of the foot-structures of the Ungulates.-C. A. White, progress of invertebrate paleontology in the United States for 1880.-Carl F. Gissler, evidences of the effect of chemico-physical influences on the evolution of branchiopod Crustaceans.-Dr. R. W. Schufeldt, notes on a few of the diseases and injuries of birds.-A. S. Packard, jun., the brain of the locust (with three plates).

Bulletin of the United States Geological and Geographical Survey of the Territories, vol. vi. No. 1.-On the vegetation of the Rocky Mountain region and a comparison with that of other parts of the world, by Asa Gray and Joseph D. Hooker (pp. 1, 77).-On some new Batrachia and Reptilia from the Permian beds of Texas; on a wading bird from the Amyzon shales; on the Nimravida and Canide of the Miocene period; and on the Vertebrata of the Wind River Eocene beds of Wyoming, by E. D. Cope.-The osteology of Speotyto cunicu laria, var. hypogaa, and on the osteology of Eremophila alpestris, by Dr. R. W. Schufeldt.-A preliminary list of the North American species of Agrotis, by A. R. Grote.