a peptic ferment is very rare among invertebrates; a ferment similar to thrypsine, on the other hand, is met with among different classes of these animals.-M. Plateau communicates an account of experiments (with the graphic method and poisons of the heart), on the movements and innervation of the central organ of circulation in articulate animals, Inter alia, section of the cardiac nerve diminishes the number of pulsations (in vertebrates, it produces acceleration).-M. Renard describes the diabase of Challes, near Stavelot, in the Cambrian system. Dr. Koninck continues his researches on Belgian minerals; and there are some papers on mathematical subjects.

THE Bulletin de l'Académie Impériale des Sciences de St. Pétersbourg (vol. xxv. No. 2) contains the following papers of interest :-On the occurrence of the musculus peroneo tibialis in Quadrumana, by Dr. Wenzel Gruber. On a control barometer, by H. Wild (with plate). On the reduction of Kirchhoff's spectral observations to wave-lengths, by Dr. B. Hasselberg.On the observed ingress of Mercury upon the solar disc, at the transit of 1878, May 6, by O. Struve, of Pulkowa (with plate), -Catalogue of forty-two new red stars, by E. Lindemann.On the Russian species of the mollusc Clausilia, Drap., by Dr. Oskar Boettger.-On the theory of curves of the shortest parameter on curved surfaces, by F. Minding. On the hexylenes resulting from tertiary hexylalcohols and their polymerisation, by L. Jawein. On the action of tertiary iodide of butyl upon isobutylene in the presence of metallic oxides, by J. Lermontoff. -On tetramethylethyl and its derivates, and on the chemical composition of pinacone, by D. Pawlow.

taken east of the moon give always a result thirty or forty seconds different from those taken west, though his mean result he says was entirely satisfactory; and until the early part of this century all East Indian longitudes were in error nearly 3m. to the east, a result which very nearly agrees with the errors resulting from these observations, supposing them to have been deduced from the new moon of five to eight days old, probably the most convenient time at which to take them from the sun. The whole series, it was stated, consists of 250 separate distances, each distance being either a mean of three or two, or else only one observation, there being about an equal number of each class, though there is no reason to think that the last are less trustworthy than the others in any serious degree; the Greenwich mean time for each being established, with the exception of a very few, within certainly ten seconds. Only 200 of these, the number at present thoroughly verified, were discussed on the present occasion. Classing these in groups of about forty, it was found that the first group gave thirty-two results where the measured distance was in defect of the theoretical distance, and thirteen in which it was in excess. Assuming the rule given in p. 417 of the paper referred to to be correct, this result exactly agrees with what might be expected, it being almost always most convenient, especially for a beginner, to take lunars, at any rate from the sun, under such circumstances as will give this result, while the example of India, founded apparently on observations made at Madras, seems to imply this probable facility, and also that they were made on the new moon, these being more easily taken in our hemisphere than those made on the old one. In the four remaining groups the proportions are 26 to 18:28 to 15: 25 to 17: 17 to 14: giving a total of 128 observations in defect, and 77 in excess. Rejecting three or four certainly ques

pinacone, by M. D. Pavloff. - On the glucose derived from lactose, by M. Foudakovsky. On the action of bromide of aluminium in the formation of the bromides of aromatic hydrocarbons, by G. Gustavson. On the dextrogyrate terpene obtained from Russian terpentine, by F. Flavitzky. On the chemical structure of terpenes, by the same. -On dibenzoyldinitrodiphenol, by M. Goldstein. -On some new mineral springs in the Caucasus, by E. Wroblewsky. -On the influence of the surrounding medium upon electrodynamical actions, by J. Borgmann. On the determination of the magnetic function of iquids, by the same.

Verhandlungen der naturforschenden Gesellschaft zu Freiburg i. B. (vol. vii. part 2).-From the part we note the following papers: On organic cyanides and their decomposition, by A. Claus.-Note on wine analysis, by the same. - On the equilibrium of a system of expanded molecules and the theory of elastic after effects, by E. Warburg. Observations on the torsion oscillations of an iron wire heated to redness, by Dr. Messer. On the sensitiveness of alum crystals towards minute variations in the concentration of their mother-liquor, by F. Klocke.

SOCIETIES AND ACADEMIES
CAMBRIDGE

Philosophical Society, October 21.-Dr. Pearson read a paper on a series of lunar distances taken by him during the years 1875-77, mostly at Cambridge and at a place not far distant, the longitude and latitude of each spot being accurately known. He said that they entirely bore out the conclusions at which he had arrived some time back from a much smaller number of observations, and which were communicated by him to the Society in a paper read by him, March 13, 1876 (see Proceedings, ii. pp. 414-418), viz., that the errors are such as cannot be called errors of observation of any kind, and may probably arise from the solution of the spherical problem on which the result depends not being, as at present given, strictly accurate. It was mentioned that there is much to justify this conclusion; for example, this method of obtaining longitudes is not much resorted to now in practice (from which it may be argued that it is actually found inaccurate). It is not formally adopted in Germany, though it still is retained in the Nautical Almanac, and in the corresponding publication, the Connaissance des Temps, issued at Paris. Capt. To Capt. Toynbee, F.R.A.S., in a paper in the Nautical Magazine for February, 1850 (of which there is an abstract in the Monthly Notices of the R.A.S.), distinctly states that lunars

and 2' 48" in excess. The true mean has not yet been ascertained, but is certainly in each case not far from I'-1' 20"; which, on an average, will give the observer an error of about half a degree of longitude, or of twenty to thirty-five miles, advancing from our own latitude to the equator. There are probably not a dozen clear exceptions to the rule suggested in the communication of March, 1876, that if the luminaries are both on the same side of the meridian, the observed distance is always in defect of the true if the moon be nearest to it, and in excess if she is farther distant; while the same rule holds good, but with less certainty, when the two luminaries are on different sides. The only exceptions seem to arise where the one more distant from the meridian has a greater altitude than the other, or is of a considerably higher declination, and when the distances are very great, i.e. from 120° to 130°, in which case the measured distance seems generally ally to be slightly in excess of the true; but, as might naturally be expected, these last distances cannot often be taken in our own climate. It was as explained explained that all the reductions had been made by Borda's formula, stated in the Philosophical Transactions for 1797 to have been the first strictly mathematical solution of the problem. But the results vary only by a few seconds of arc from those given by the system adopted in the large folio published in 1772 by Mr. Shepherd, Plumian Professor at Cambridge University under the superintendence of the Commissioners of Longitude, and while Dr. Maskelyne was Astronomer-Royal; or from other methods which it is believed are allied to this. Two examples were also exhibited of distances reduced according to the elaborate method suggested by Bessel in the Astronomische Nachrichten of 1832; Bessel's results, however, do not differ to any great extent from those obtained otherwise. It was suggested that the problem is really one of spherical trigonometry, and from the fact that the errors seem to depend on the position of the luminaries towards the meridian, whereas the old methods of solution depend on their altitudes, and also that the different ways suggested for eliminating the error due to the difference between the geocentric and geographical latitude of the place of observation give different results, a hope was expressed that if these two circumstances were thoroughly reconsidered in dealing with the question, means might be found of discovering a farther correction of the observed distance, which would give a really accurate result.

MANCHESTER

Literary and Philosophical Society, October 15.-J. P. Joule, F.R.S., &c., president, in the chair. Relative brightness of the planets Venus and Mercury, by James Nasmyth, C.1 C.E., F.R.A.S., Corresponding Member of the Society. "On many occasions, when observing Mercury and Venus in full daylight,

I have always been impressed with the strikingly inferior brightness of Mercury as compared with Venus; and as such a condition is the very reverse of what might be expected by reason of Mercury being so much nearer to the sun than Venus, I awaited the rare event of a very close conjunction of these two planets that occurred on September 26 and 27 last. With the advantage of a perfectly clear sky I had the two planets before me for several hours, so to speak, side by side in the field of the telescope at the same time, thus affording me a most perfect opportunity for making a comparison of their relative brightness. It is difficult to convey in words an exact impression of the difference in the brightness of such objects, but I may attempt to do so by stating that Venus looked like clean silver, while Mercury looked like lead or zinc. Were I to indicate my impressions by way of number I would say that Venus was fully twice as bright as Mercury. So remarkable an inferiority in the brightness of Mercury, notwithstanding his much greater nearness to the sun, appears to me to indicate the existence of some very special and peculiar condition of his surface in respect to

to present interesting numerical relations. Decipium is so called from decipiens, deceiving. The didymium of cerite is probably a mixture of several bodies, by M. Delafontaine. This is based on spectral observations.-Reply to a recent communication by M. Hirn, on a gyroscopic apparatus, by M. Gruey.-Classification of double stars, by M. Flammarion. Of the 11,000 double or multiple stars discovered, he finds there are only 819 that give certain indications of a relative motion of the components. These groups are divided into 731 doubles, 73 triples, 12 quadruples, 2 quintuples, and I sextuple, in all 1,745 stars variously associated. Of these couples in motion 558 have been found with orbital systems, and 316 whose components have been connected merely by the chance of celestial perspectives and form optical groups. In the orbital systems there is a preponderance of retrograde motion from north to south by west (Several other facts are given.)-On the integration of the equation (1) Ay'2 + Byy' + Cy2 + Dy + Ey + F = O, by M. Alexeeff. - On involution in curves of n degree, by M. Serret.-Remarks on two integrals obtained

the nature of his envelope, if such exist, or of that of his surface, by which the fervid light of the sun's rays falling on him are in a great measure quenched or absorbed so as to leave but a small residue to be reflected from his surface. If this be so, it appears to me to be reasonable to suppose that the absorption of so much light must result in a vast increase in the heat of the surface of Mercury beyond what would have been the case had Mercury possessed the same surface conditions as Venus. Whether in the progress of spectroscopic investigation we shall ever be enabled to detect some evidence of metallic or other vapours or gases clinging to or closely enveloping the surface of Mercury that might in some respect account for so remarkable an absorption of the sun's light, we must be content to await the acquirement of such evidence if it ever be forthcoming. It appears to me, however, to be well to raise such a question, so that our astronomical spectroscopists may be on the outlook for some evidence of the cause of so very remarkable a defective condition in the light-reflecting power of Mercury to which I have thus endeavoured to direct attention." - On the water of Thirlmere, by Harry Grimshaw, F.C.S., and Clifford Grimshaw.

PARIS

Academy of Sciences, October 28.-M. Fizeau in the chair.-M. De la Gourmerie read a note on the works of the late M. Bienayme. -The following papers were also read:-On the decomposition of hydracids by metals, by M. Berthelot. The heat of formation of gaseous chlorhydric acid from its elements is surpassed by that of all anhydrous chlorides, even chlorides of lead, copper, mercury, and silver; gold is the only exception among ordinary metals. The inference that all these metals, except gold, must decompose chlorhydric gas with liberation of hydrogen, is confirmed by experiment. Platina and palladium, also, their chlorides having low heats of formation and little stability, did not decompose chlorhydric gas up to 550°. On Vice-Admiral Cloué's "Pilote de Terre Neuve," by M. Faye. On the state in which carbonic acid exists in the blood and the tissues, by M. Bert. The escape of carbonic acid during the respiratory act requires a dissociation of the super-carbonised salts of the blood. These salts were saturated with carbonic acid neither in the arterial nor the venous blood, nor in the tissues. The life of the anatomical elements can only be maintained in presence of carbonic acid in the state of combination. When the alkalis are saturated, and this gas appears in excess in the state of simple solution it rapidly causes death. Influence of the nervous system on the phenomena of absorption, by M. Moreau. He attached to the dorsal fins of fishes that had swimming bladders a small glass balloon, lighter than the water, and in a few hours the volume of the fish had diminished through absorption of a part of the air contained in the bladder. When a piece of metal was substituted for the balloon, the volume of the fish increased. There is thus a sensation of thrust upwards or downwards, and it is under influence of the former that absorption of air in the bladder takes place, probably through a reflex action. -On decipium, a new metal of samarskite, by M. Delafontaine. In the samarskite of North Carolina he finds yttria, erbine, terbine, philippine (yellow (PPO), equiv. about 90; characteristic absorption band about 449 in x), decipine (white (DpO), equiv. about 122, band 416); thorine and oxides of didymium and cerium. The equivalents of the metals in some of these earths are shown

ply to an observation of M. Boltzmann, by M. Lévy. On the magnetisation of tubes of steel, by M. Gaugain. When a system formed of two parts having different coercive forces is subjected to action of a weak current, the part having the least coercive force is always that which takes the strongest magnetisation (whichever its position, tube, or core). -On a telephone call, by M. Perrodon. This consists in connecting a Ruhmkorff coil with the plate of the telephone, so as to get a loud continuous sound. On the transformation of valerylene into terpilene, by M. Bouchardat.-Artificial reproduction of melanochroïte, by M. Meunier. This is by keeping fragments of galena in dilute aqueous solution of bichromate of potash. On the elimination of salicylate of soda, and the action of this salt on the heart, by MM. Blanchier and Bochefontaine. It stimulates various secretions, notably the salivary. In man it is at once expelled by the kidneys (appearing in the urine in 20 mm.); in the dog it appears both in the urine and the saliva, also in the bile and pancreatic fluid. The hypersecretion of saliva is due to action of the salicylate on the grey substance of the central nervous system. In strong doses, the salt stops the heart in diastole.On parthenogenesis in bees, by M. Sanson.

A Question raised by the observed absence of an Atmosphere in the Moon.-S. TOLVER PRESTON

Remarkable Local Colour-Variation in Lizards. -ALFRED R. WAL-
LACE and BARON DE BASTEROT

Termites kept in Captivity by Ants.-HENRY O. FOREES
Colour-Blindness. CLEMENTINA BLACK; EDMUND MCCLURE
Carrier-Pigeons. -THOMAS STEVENSON, C.Е.
Globular Lightning -CHARLOTTE HARE
Speaking-Trumpets.-Wм. CHAPPELL.

Toughened Glass.-G. C. DRUCE
POTTERY AT THE PARIS EXAIBITION
SUN-SPOTS, ATMOSPHERIC PRESSURE, AND THE SUN'S HEAT. By
JOHN ALLAN BROUN, F.R.S.

THE SIZE OF THE TIGER. By Sir J. FAYRER, F.R.S.
THE TELEPHONE, ITS HISTORY, AND ITS RECENT IMPROVEMENTS, II.
By Prof. W. F. BARRETT (With Illustrations).

OUR ASTRONOMICAL COLUMN:

The Late Solar Eclipse at Watson's Station.
Calculation of Excentric Anomalies.
The Minor Planets

GEOGRAPHICAL NOTES

THE WERDERMANN ELECTRIC LIGHT

NOTES

ON THE VERTICAL DISTRIBUTION OF THE LIGHT FROM LIGHTHOUSES
PLACED AT HIGH ELEVATIONS ABOVE THE SEA-LEVEL. By T.
STEVENSON, С. Е.

MEDICAL ENDOWMENTS AT OXFORD
ON THE THERMAL PHENOMENA PRODUCED BY THE PASSAGE OF ELEC-
TRICITY THROUGH RAREFIED GASES. By Dr. NACCARI and M.
BELLATI.

NOTES FROM NEW ZEALAND
UNIVERSITY AND EDUCATIONAL INTELLIGENCE

SCIENTIFIC SERIALS

SOCIETIES AND ACADEMIES. . . . .

3

3

3

THURSDAY, NOVEMBER 14, 1878

CLEOPATRA'S NEEDLE AND THE WIND PRESSURE

THE statements recently made in the Times respecting the stability of Cleopatra's needle and the maximum intensity of the pressure of the wind in this country have awakened much interest, if not anxiety, about the subject. The appearance of the lofty obelisk balanced on so small a base suggests to many the thought of an egg | standing on its end, and presents every idea of instability. This idea is much amplified by a very erroneous estimation, we believe, by most persons of the real dimensions of the base; we have heard this estimated at various diameters down to two feet, but in reality it is in no direction less than five. The statement that the stability of the obelisk is sufficient to withstand a wind pressure of 80 or 90 lbs. per square foot having been made, the storm from Liverpool at once broke on it and upset people's minds, if not the monolith. Thus we learn, from the observations taken by Mr. Hartnup, the astronomer at the Liverpool Observatory, that on January 30, 1868, "it began to blow strongly about 9 A.M., and from that time gradually increased in violence until halfpast II P.M. on the 31st, when there was one gust of wind which registered 51 lbs. on the square foot. From this time the gale rapidly increased till noon next day, blowing with a severity quite unprecedented in this country. The anemometer which has been erected at the Bidston Observatory is made to register up to 60 lbs. on the square foot, the idea being that no gale would reach that degree of violence. Between eleven o'clock and one o'clock, however, the registering pencil was driven far beyond this limit, and Mr. Hartnup calculated that at several periods the pressure could not have been less than from 70 lbs. to 80 lbs. on the square foot. The anemometer was erected in 1851, and the most severe gale registered up to this time was in December, 1863, when there were three gusts which registered 45 lbs. to the square foot." Further details respecting this remarkable hurricane will be found in the Journal of the Scottish Meteorological Society, from which we find that at Glasgow, from 1.15 P.M. to 1.30 P.M., twenty-one miles of wind passed the observatory, giving a velocity of eighty-four miles per hour, or corresponding to a pressure of 35 lbs. to the square foot, while the strongest gusts registered 42 lbs. on the square foot. At Edinburgh the gale was more severe than at the latter place; cabs and horses are said to have been blown over, but there is no record of the pressure or velocity as there was unfortunately no anemometer in working order. Many authorities state that the maximum pressure of the wind does not exceed 55 lbs. to the square foot in this country, and as this is the figure commonly assumed by engineers in the design of large structures, it is of the greatest importance that the trustworthiness of the Bidston anemometers should be ascertained. Pressure anemometers are obviously liable to errors from the varying modulus of elasticity of their springs and the momentum of their moving parts and supports, while Robinson's anemometers may give a maximum velocity due to small eddies, which VOI. ΣΙΥ.-No. 72

is much in excess of the true value. Mr. John Dixon in his letter to the Times on the subject gives a good illustration of a pressure of 80 lbs. to the square foot by comparing it to the weight on the floor of a densely-crowded room. It has been ascertained by experiment that the weight of a crowd of persons can attain 80 to 120 lbs. per square foot, the latter figure being reached only when the experiment was made with labourers of above the average stature packed as closely as possible, and the former being commonly taken as the maximum load to which the platform of a bridge can be subjected by a dense mixed crowd. Thus Mr. Dixon remarks, "the 'windows of a building certainly have to bear an equal strain with the walls, and I suppose it would be immaterial to the glass whether it was placed vertically or horizontally. densely packed crowd hardly weighs 80 lbs. per square foot of the space it stands upon. Reduce therefore the theory to common sense; would any one dream of standing on a floor formed of glazed window sashes?" On the whole we rather think not, even if, to make the case analogous, means were taken to distribute the pressure uniformly, and we are forced to the conclusion that either the Bidston Observatory is a very strongly constructed building with window-sashes and glass of unusual strength, or that the anemometers are untrustworthy.

A

Leaving now the question of the maximum pressure of the wind to be decided by meteorologists, there remains to be ascertained what that pressure would have to reach on the banks of the Thames to endanger the existence of the obelisk. Mr. Dixon's assurance has probably set the fears of many at rest; he says: "As to its stability there need be no fear-130 lbs. of wind-pressure would not upset it. The columns of the Times are not the place to ventilate calculations and figures." We can assure Mr. Dixon that these calculations would be of sufficient interest to the readers of NATURE to find a place in its columns, but in their absence we are obliged to fall back on our own. The widths of the top and bottom of larger face of the obelisk are respectively 64 inches and 95 inches, the height being 60 feet 6 inches exclusive of the pyramidal point, which would be 7 feet high if intact; assuming, then, an additional foot of height for the lower rounded end, the moment about the base of the pressure on the area of the larger face will be 12,931 foot pounds for a wind pressure of I lb. on the square foot. The weight of the stone is estimated at 196 tons, whence, on the assumption of perfect rigidity, the ultimate stability would be 196 tons X radius of base (2.5), and the corresponding wind pressure

=

196 × 25 × 2240 = 84.88 lbs. per square foot. But

12,931

C

bodies emit light with heat to be 977°, and shows experimentally that as the temperature of an incandescent body rises it emits rays of an increasing refrangibility; also that the amplitude of any particular vibration increases with the temperature, and that to every particular wave-length there belongs a particular colour. But even more remarkable are the deductions he makes regarding light and heat, deductions which, though evident now, perhaps, in the present state of knowledge, had by no means then the appearance of undoubted truths. He boldly asserted that light and heat were effects of radiation and not forces existing in the radiations themselves.

It is, however, with photographic research that the name of Draper is most generally linked; and as his researches in this line commenced in 1837, two years before the announcement of Daguerre's and Fox Talbot's discoveries, his claim to be considered one of the pioneers in photography admits of no contravention. In his memoir on "Studies in the Diffraction Spectrum" we read: "Several years before the commencement of the discovery of photography by Daguerre and Talbot (1839), I had made use of the process for the purpose of ascertaining whether the so-called chemical rays exhibited interference, and in 1837 published the results in the Journal of the Franklin Institute, Philadelphia (July, 1837, p. 45). In this, as will be seen by consulting that publication, I was successful." In his memoir of 1843, he describes the mode in which he photographed the spectrum, from the blue to the ultra-violet, and from near Cin the red region to a point some distance below the limit of visibility. The apparatus he employed would at the present time be considered, perhaps, somewhat rude, but, as is well known, the roughest appliances in the hands of a true philosopher are sufficient even for delicate experiment. Thus, in photographing his spectrum we find that he worked before the days of collimating lenses, and with a consequent feebleness of light which was a serious matter when the slow (as compared with that now extant) process of Daguerre was employed for registering the impressions of the radiations. Half an hour's exposure was not too long to give to obtain a developable image, whereas now as many seconds as he gave minutes, with the same size of spectrum and width of slit, would be more than ample. The method by which Draper registered the lines in the red and ultra-red regions is fully treated of in his fifth memoir. The plate received a preliminary exposure to white light, and was then exposed to spectrum; or feeble daylight was allowed access to the plate whilst being similarly exposed; the result, on development by mercury, being that the dark lines in these regions were registered as light lines on a dark background, instead of as dark lines on a white background. This action Draper, Claudet, and others ascribed to the

undevelopable. Whatever may be the explanation of this phenomenon, we have in Draper's photographs of the least refrangible region a gigantic feat, considering the date at which it was performed. Though recent methods may outstrip the more antiquated one as regards rapidity of execution, yet it is due to him to acknowledge that he has long priority in showing that chemical action was not confined to the least refrangible end of the spectrum. As regards the application of photography to portraiture, to our author seems to belong the honour of having taken the first portrait by the Daguerreotype process, and the arrangements adopted for the purpose read rather comically in these days of quasi-instantaneous pictures. In his memoir, "On Taking of Portraits by Photography," he says :- "On a bright day, and with a sensitive plate, portraits can be obtained in the course of five or seven minutes in the diffused daylight. .. Difficult parts of the dress. require intervals (exposure) differing considerably, to be fairly copied, the white parts of a costume passing on to solarisation before the yellow or black parts have made any decisive representation. We have therefore to make use of temporary expedients. A person dressed in a black coat and open waistcoat of the same colour must put on a temporary front of a drab or flesh colour, or, by the time that his face and the dark shadows of woollen clothing are evolved, his shirt will be blue, or even black, with a white halo around it." We are sure that the author cannot have regretted the supercession of a process which entailed such "dodging" to render a portrait practicable, more particularly at the time when he sat for the photograph from which the admirable portrait forming the frontispiece was engraved.

To this same memoir we have also an append in which it is shown that Dr. Draper had priority in taking a photograph of the moon; and when it is considered that the exposure was twenty minutes, and the diameter of the image about one inch, it would not be surprising had it lacked in detail. By an extract from the minutes of the New York Lyceum of Natural History we learn that in this photograph we have "a distinct representation of the moon's surface."

To yet another discovery of Draper's we must refer, since, like some others of his, it has been re-discovered quite recently. He says, in his description of the Daguerreotype process, "On these principles" (he alludes to the different photographic effects produced by different rays of light) "it is plain that an achromatic object-glass is by no means essential for the production of fine photographs; for if the plate be withdrawn at a certain period when the rays that have a maximum energy have just completed their action, those that are more dispersed but of slower effect will not have had time to leave any stain. We work, in fact, with a temporary monochromatic

as an objective he tested his theory, and found that on this principle he could photograph an engraving, with all its finest details present. The similarity between Janssen's use of an uncorrected lens for solar work and this is apparent.