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Mubarak, Minister of Worship at that time. his return to Berlin he was appointed exThis decree directed that a building be erected traordinary professor in the university, and in in the ministerial premises, of a capacity for the the following year he was created a member proper accommodation of 30,000 volumes, in of the Academy. In 1829 he took part in which should be collected and preserved the Alexander von Humboldt's journey to Asia. books, maps, scientific instruments, and papers, Having become Secretary of the Academy in belonging to the public benevolent institutions 1842, he was appointed ordinary professor at and public offices of the country, in such a the university in 1847. A sketch of his first shape as to be convenient for the use of the journey is contained in “Naturgeschichtliche public. The library will include the "Old Reisen durch Nordafrika und Westasien in den Library," founded by Mehemet Ali in 1838, Jahren 1820–25, von Hemprich und Ehrenconsisting principally of works printed at the berg." The scientific results of this journey public printing-office. Of the libraries of the are contained in “Symbole physicæ seu public benevolent and religious institutions to Icones et Descriptiones Mammalium” (1828– be incorporated in it, a writer in the Allge- '33), “Symbolæ physicæ Avium” (1828), meine Zeitung names as known to him those “Symbolæ physicæ Insectorum" (1829–34), of thirty-one mosques, three Talijne, or der- and “Symbolæ physicæ Animalium Evertebravis cloisters, one school, and three private torum sepositis Insectis" (1829-31). His great residences, containing in all 16,562 volumes, scientific fame is based chiefly on the knowlexclusive of the collection in the mosque of edge of microscopic organisms, which was Al Azhar. The library will be made as com- considerably promoted by him. Although his plete as possible in the special departments of observations have been superseded by more "Egyptology," of which all works published, recent ones, he must be regarded as the founder in all languages, will be procured, and of Orien- of this school. Among his works pertaining tal literature. The collection of Arabic works to this subject the most important are: “Orgawill be carefully looked to, and it is antici- nisation, Systematik und geographisches Verpated that this department of the library of hältniss der Infusionsthierchen" (1830), "Zur many valuable writings, now practically out of Kenntniss der Organisation in der Richtung the reach of European scholars, will be made des kleinsten Raums (1832–'34), Zusätze accessible and useful. It is intended also, in zur Erkenntniss grosser Organisation im the scientific departments, to provide the kleinen Raum" (1836), and his principal work, works necessary for the pursuit of the profes- “Die Infusionsthierchen als vollkommene sional studies of engineers, architects, and Organismen, ein Blick in das tiefere Leben others, to professional men, without their hav- der organischen Natur” (1838), with 64 coping to go out of the country. The library is perplates engraved from his own drawings. open to every one for consultation, on the He was led by the discovery that many firesingle condition of his presenting a certificate stones, chalk, and other mineral substances consigned by his consul or some prominent man sisted of layers of microscopic organisms, to the of the city ; but books cannot be taken out. observation of the smallest fossil creatures. The collection has already become very valu- On these researches he reported in “Die Bilable. During 1876 it was enriched by the ad- dung der europäischen, libyschen und uralidition of a large portion of the works, chiefly schen Kreidefelsen und des Kreidemergels Oriental manuscripts, of the late Mustafa Fazyl aus mikroskopischen Organismen” (1839), Pasha, of Constantinople.

“Die fossilen Infusorien und die lebendige The Assembly of the Delegates of Egypt Dammerde” (1837), and his principal work on was opened on the 23d of November. The this subject, " Mikrogeologie” (1864). Among Khedive recommended the establishment of his later works are: “Uebersicht der seit 1847 an Egyptian national bank.

fortgesetzten Untersuchungen über das von The war with Abyssinia, commenced in der Atmosphäre unsichtbar getragene reiche 1875, continued through the greater part of organische Leben" (1871), “Nachtrag zur 1876, being in its results rather disastrous to Uebersicht der organischen Atmosphärilien " the Egyptians. (See ABYSSINIA.)

(1872), and "Mikrogeologische Studien über EHRENBERG, CHRISTIAN GOTTFRIED, & das kleinste Leben der Meerestiefgründe aller German naturalist, born April 19, 1795; died Zonen " (1873). June 27, 1876. He entered the University of ELECTRICITY. Electricity and the TheLeipsic in 1815, studying at first theology, and gry of Comets. — Reitlinger and Urbanitsky then devoting himself to the study of the have addressed to the Paris Academy of natural sciences and of medicine. In 1816 he Sciences a memoir on a new electrical repalwent to Berlin, where he graduated as doctor sion and its application to the theory of comof medicine in 1818. In the following year ets. It is known that the luminous column the Academy of Sciences furnished him and produced in a Geissler tube gives rise to a his friend Friedrich Wilhelm Hemprich with phenomenon of attraction, when the finger the means for a long scientific journey. They or any conductor whatever is brought near went to Egypt and its neighboring countries, the tube. The authors experimented with two from which Ehrenberg returned alone in 1826, tubes that had contained, the one bromine Hemprich laving died at Massowah. Upon and the other perchloride of tin. The light

obtained was greenish and of peculiar aspect, creases with the width of span of the arch. The in which the spectroscope showed neither the principal length-line, then, is the sum of the most rays of bromine nor those of tin perchloride, tion is the most positive point of the leaf at the but only the three well-known bands usually fore-end of the hindermost third of the midrib. attributed to the spectrum of carbon. These And, as in the whole leaf all is symmetrical on bands are the same which Vogel and other the two sides of the midrib, so in each leaf-half all observers have designated as forming the is symmetrical on the two sides of the middle crossspectrum of comets. Besides, the luminous be disturbed only in that the most positive point in column thus produced gave rise, not to a the midrib is displaced back from the middle. phenomenon of attraction, but to a very well The examination of the upper surface of the leaf defined repulsion. The authors, after re- offers great difficulties, owing to its sensitiveness. peated experiments, are firmly convinced that These having been overcome, it is found that the these curious phenomena are due to the ex

same distribution of tensions prevails as on the

under surface. treme rarefaction of the gases employed; and, since the gas forming the tails of comets is

The source of the electro-motive action he undoubtedly in a state of high rarefaction, supposes to reside in the interior of the leaf, they conclude that this is the cause of the

nor can it, according to him, arise from heterorepulsion of the sun on the comet's tail, the geneity of surface. The primary organs of the sun being then considered simply as a good hairs, the fibro-vascular cords, nor the epider

electric forces are neither the disk-glands, the conductor. Electrical Phenomena in Plants.—The leaf in the halves of the leaf and in the midrib.

mis, but the cylindrical cells of the parenchyma of the plant Dionæa muscipula, one of the These cells are endowed with forces of such a carnivorous plants, has been found by Dr. kind that the positive electricity is driven from Burdon-Sanderson to possess an electro-motive action. The saine author has shown that the middle of the cell to each of the two poles, when contraction takes place in the leaf there which are positive poles to the middle. is a negative variation of the current; he has two kinds : stimulation movements, and resorption

The mechanical movements of the plant are of also observed in the leaf something corre- movements. In the former, the leaf closes very sponding to the latent stimulation of muscles quickly after stimulation, within a minute or so, all and the electrotons of nerves. This subject parts moving simultaneously. In a few hours it has lately been investigated by Hermann Munk, begins to open again, and is quite

open after

twentywhose results have been published in Der Na- four to thirty-six hours. It is then susceptible of turforscher. Briefly they may be stated as the other hand, is more rare, and occurs when a follows:

small piece of flesh, albumen, or the like, is care

fully laid on the leaf-surface, avoiding the sensitive Applying the unpolarizable electrodes to the under hairs. The closure which follows is very slow, not surface of a leaf, a current appears in (say) an up; beginning for some hours, and being completed only vard direction, i. e.,

flowing in the leaf from the end in one to two days. The movements of the two of the petiole or leaf-stalk (call it the fore-end of the halves are irregular and unsimultaneous, and depend leaf) to the free end or point of the leaf (which on the place of contact, from which they spread may be called the hinder end). Points situated sim- outward. The reopening þegins after several days, ilarly on the two halves of the leaf are homogeneous, and takes several days to be completed; and during hence on the two sides of the midrib all is symmet- this time the leaf is not, or is very little, susceptible rical. Conceive the midrib divided into two un- of either stimulation or resorption movements. The equal parts, a shorter hinder part and a longer fore leaf may die after one such resorption movement, part; then in each of these parts every point nearer and two or three always prove fatal to it; it opens the inner end is positive to every more distant point. no more. The most positive point of the midrib lies about the We now come to the electrical phenomena in stimfore-end of its hindermost third, and with increas- ulation, of which Dr. Sanderson said that they ing distance from this point the positivity decreases presented a negative variation similar to that of the toward both ends.

muscle-current. The electrodes were placed on the Suppose lines drawn on the surface of a half-leaf under surface of the midrib, as being the only part at right angles to the midrib; and call these cross- of the leaf which, during movement of the latter, lines of the leaf. Every point of such a cross-line does not alter in position. On stimulation through pmres negative to the corresponding point of the movement of the sensitive hair, there occurs, not a midrib; and regularly the negativity of these points simple negative variation, but, as the author exincreases first to a maximum, and then, on to the presses it, a positive variation with negative primary outer leaf-border, decreases. The most negative impulse, which he calls double variation. This point of the cross-line never coincides with the mid- electrical phenomenon occurs even when, notwithdle of the line, but is always nearer the leaf-border standing stimulation, there is no movement of the than the midrib.

leaf. The latter circumstance renders possible an By connecting the most negative points of all the examination also of the leaf parenchyma; and the sections, we have a principal line of length nearly same double variation is here observed. parallel to that of the midrib. All points in this As to the explanation of this double variation, the fine are homogeneous. So also are related points supposition that all the cells pass first through a of other lines of length running parallel to the mid- negative, then through a positive variation, is to be rib, and lying inward from the principal length- rejected, the process is rather (the author thinks) line. or the middle parts of two cross-lines, which that through stimulation the cells of the upper sre both in the fore or both in the hinder halves of halves of the half-leaf parenchyma and of the upper the leaf-halves, the middle nearer to the fore or to midrib parenchyma experience a negative variation, the binder leaf-border respectively is always posi- those of the under halves of the half-leaf parenchytire to the more distant middle, and the force, down- ma and of the under

midrib parenchyma a positive ; Fard in the former case, upward in the latter, in- that

is, the negativity

of the middle of the cells to

their poles increases in the former cells, on stimula- bright-blue, dark-blue, and violet glass, the plate tion, and decreases in the latter.

was equally negative. Variation in the Electrical Condition of the In free sunlight the illuminated strip was first

Strongly-oxidized copper strips were next tested. Heart.-It is known that during every revolu- strongly positive, then weakly negative, then the tion of the heart its muscular tissue undergoes action ceased. Behind red glass the plate was pretty singular variations of temperature and excita- strongly positive, but the deflection of the needle bility, a dimination of excitability, and a rise the strip was very strongly positiye, but very soon the of temperature, coinciding with the systole, action diminished; on darkening, a strong negative while during diastole the opposite phenomena deflection occurred. Behind dark-green glass the are manifested. Supposing it to be probable plate was first wenkly positive, and then negative; that corresponding variations of the electrical behind dark-blue glass it was also negative, and condition of the cardiac muscle could be de- sunlight; behind violet glass the action was similar.

this change was more considerable than with free tected, Marey has made a series of experi The author describes also the behavior of copper ments to determine this question. The gal- in sulphate-of-copper solution, and the behavior of vanometer, owing to the inertia of its needle, silver, tin, brass, zinc, and platinum, which metals is unsuitable for the observation of sudden

were examined in the same way. changes in the intensity of currents. Hence, Effects of Lightning on Different Species of in Marey's experiments, Lippmann's elec- Trees.-The effects of lightning on different trometer was employed. The heart of a frog species of trees have been made a subject of was placed on two non-polarizable electrodes, investigation by Daniel Colladon, who has one of which supported the apex of the ven- communicated to the Geneva Society of Nattricle, while the auricles rested on the other. ural History the results of his observations. Two successive negative variations of the cur- He states that when a poplar is struck all the rent were indicated by the electrometer during upper part of the tree remains perfectly sound each cardiac systole: one of these was sudden, and green. The height above the ground at and corresponded with the abrupt contraction which the injuries appear does not, in large of the auricles; the other was more gradual, poplars, exceed one-third of the tree's height. and coincided with the slower movement of These injuries commence immediately below the ventricle. The phases of electrical varia- the junction of the strong branches with the tion are thus seen to be similar to those of the trunk. In general, they do not reach quite to work done by the muscle.

the ground. It is always the tallest poplar of Influence of Light on the Electrical Be- a group that is struck. In some cases the havior of Metals.—In order to determine the storm will pass over trees of other species and action of light upon the electrical behavior of will burst on poplars, though they be of less metals in water-a subject which many years height. The author has never met with any ago engaged the attention of E. Becquerel - traces of carbonization. The cases in which Hankel, a member of the Leipsic Gesellschaft several poplars are injured by a single disder Wissenschaften, employed two carefully- charge of lightning are rare. One such case is cleaned and newly-scoured strips of copper, recorded by M. Colladon, where three poplars one of which he fixed in a porous clay cell by were damaged by the same stroke. These trees means of a cork stopper. This cell was filled stood in a straight line, and about twelve feet with water, and placed in a larger vessel of distant from each other. glass containing some water, in which the Magnetic Properties of Nickel and Cobalt.other copper strip was so immersed as to have The researches of Hankel into the magnetic one of its surfaces turned toward the source properties of nickel and cobalt are worthy of of light. The two strips having been con- being recorded here. The bars of these metals nected with the wire of a galvanometer, the used in his investigations were large and pure, glass, with its contents, was placed in a black the nickel-bar being 168 millimetres long, 41.1 case having a slide for the adinission of direct millimetres broad, and 13.1 millimetres thick; sunlight or colored light to the outer strip of the cobalt-bar was of nearly the same dimencopper. The results were as follows:

sions. A bar of iron, of like dimensions, was

examined at the same time. Comparing the On access of free sunlight, the strip exposed to the iron with the nickel, it was found that, within light was negative to the one in darkness, though the limits of current-strength used, the magaction was inconsiderable ; with yellow glass, a little netism in the former increased proportionally stronger; with green and dark-blue successively, to this strength; the nickel at first, i. e., with still stronger; with very dark-violet glass it was weak currents, showed nearly the same magless again.

netic force as the iron; very soon, however, The copper strips were now oxidized by moderate its magnetism increased in less degree than in In free sunlight the illuminated strip was strongly the iron, so that with the greatest strengths of negative; on darkening again, the deflection grad- current it was little over a half of that in the ually disappeared; behind red glass the action was iron. The cobalt behaved like the nickel in less; behind light-yellow glass the plate was first that, even with moderate currents, the magpositive, then negative; on darkening. it became netism increased in less degree than the intenbehind dark-green glass the behavior was similar, sity of current; but it differed in showing a but the first positive deflection was less; behind much less strength of magnetism within the

strengths of current employed. Since, how- wires, a different deflection was obtained in ever, the increase of magnetism from the sec- each case, but these were rendered equal by ond last to the last observation, in cobalt, was inserting an additional resistance in circuit much greater than in nickel, it is not impos- with that wire whose elongation was greater. sible that, with very strong electric currents, The tube was now filled with water so as to the magnetism of cobalt may be greater than carry off the heat generated in the lower wire that of nickel. Unlike the nickel, the cobalt as rapidly as possible. It was found that the piece was not without coercive force.

galvanic expansion was only 1.2 to 2.2 per New Electro-Motor. — In a new electro- cent. of the heat-expansion; and no connecmotor recently exhibited in London by its tion was recognizable with the nature of the inventor, Chutaux, the primary force is sup- metal employed. If it be considered that plied by a battery of eight or more cells, these values, of course, can only be an upper being a modification of the Bunsen battery. limit, it will follow, from the smallness of the The elements used are graphite and unamal- effect obtained, that there is no sufficient gamated zinc, and the exciting fluids are sul- ground for the hypothesis of a special expanphuric acid and bichromate of potash in the sion power of the galvanic current. There inner (or graphite) cell, and a solution of acid can hardly be any doubt that the slight expansulphate or bisulphate of potash in the outer sion which the water-inclosed wire still shows (zine) cell. No material action is exerted on is simply and alone due to the heat remaining the zinc while the battery is at rest, hence the in it. reason for dispensing with the process of amal Magnetic Equivalent of Heat.-In Lamin gamation. Two or more horseshoe electro- and Roger's decisive experiment establishing magnets, with their poles upward, are worked the production of heat through disappearance by the current, a wheel rotating on an horizon- of magnetism, the soft iron of an electro-magtal axis immediately above and almost touch- net was placed in the reservoir of a large thering them. This wheel is practically formed of mometer of oil of turpentine; on sending an two parallel wheels joined at their circumfer- interrupted current through the spiral, it was ence by a series of soft-iron bars. As soon as observed that the liquid expanded. The conthe current is set up the wheel begins to re- clusion hence drawn was, that during each magFolve, owing to the attraction between the netization a part of the electricity goes into electro-magnets and the iron, the motion being the iron, producing magnetism, and that at the kept up, and rapidly increased, by means of a moment of demagnetization this magnetism is simple automatic * current-reverser." The transformed into heat. In further investigatprincipal feature to which the inventor draws ing this subject, Cazin employed three different attention is the construction of the transverse methods of experimentation. In the first, the soft-iron bars, each of which is composed of iron core was inclosed in an hermetically-closed seven thin plates, much being thus gained in vessel filled with petroleum, and surrounded by intensity of magnetization, and consequently in the magnetizing spiral. From the vessel promechanical power. By a series of ingenious ceeded a capillary tube, also containing petrodevices the machine is applied to the working leum, and the changes of level in it were obof pumps, sewing-machines, lathes, etc., as å served when the core was magnetized by an insabstitute for manual or foot labor. It is not terrupted current. But inasmuch as change of of course in any way intended to supersede level might arise, not from heat-action, but steam, its object being the simple and easy from the expansion of the iron by magnetism, performance of labor of a light description. the following experiment was arranged : The battery is free from smell, and, being very Into the vessel containing the liquid and the iron " constant,” will last for a long time without core were introduced some closed

glass tubes, which renewal, the trouble involved in starting and displaced a third of the liquid; the vessel was then stopping the machine being practically nil.

closed, and the experiment repeated. If the expanInfluence of the Electric Current on the this must now be the same as in the experiment

sion of the iron were the cause of the change of level, Dimensions of Iron.—The change in length of without the glass tubes; if, on the other hand, the i condnctor, through which an electric current change of the level were due to the heat produced, is passing, has been

measured by Exner, whose it must now be different, for, instead of three volumes method is free from the error caused by the of liquid, two volumes of liquid and one volume of expansion due to the heat produced by the cur- i'he experiment then revealed a difference, wbich rent. In making this measurement, two pieces corresponded to the difference of the specific heats of the same wire of nearly equal lengths were and confinements of expansion of petroleum-oil and hung one over the other, and so connected glass, with a battery that the current might be It was thus proved that the discontinuous passed through either. The lower wire was magnetization of an iron core produces heat. passed through a glass which might be filled In another method for demonstrating and with water if desired. The elongation was measuring this heat-effect, the core was an measured by resting the end of the wire on a iron tube, closed at both ends with corks, and lever carrying a mirror whose deflection was inclosing the bulb of a common thermometer. read by a microscope and scale. The current Here, again, there was heat-action when the being passed successively through the two spiral was traversed by an interrupted cur

rent. In the third method a differential ther- vious that this must occur as long as a single mometer was used, consisting of two hollow car remains on the track, or when the circuit iron cores, communicating by a capillary tube is broken by a displaced or broken rail, or any in which was a liquid index: every heat-action other cause. Hence the device may be applied in the one core was followed by an expansion over an entire line, and will indicate the condiof the contained air, and displacement of the tion of every section to a train about to enter index.

on the same. It is not affected by changes of In order to determine the cause of the de- weather. velopment of heat, M. Cazin proceeded as fol ELIO, JOAQUIN, a Spanish general, died in lows:

January, 1876, very much advanced in years. Round the iron core in the petroleum thermometer He was educated for service in the royalist two coils of 480 turns were passed, one of them being army in Spain, in which he obtained his first in the interrupted magnetizing circuit, while the commission. During the progress of a stormy of the interrupting apparatus was closed. The first public career, he served under many governcoil could now induce a current in the second, if ments. In 1860 he commanded a part of the the closures of the two circuits took place at the Carlist insurgents, and during the last Carlist proper times, as might be arranged at will. These War he also acted with Don Carlos, by whom experiments gave the greatest development of heat he had been threatened with the loss of his tinually

open. The heat was not altered when the command, and with court-martial, on several circuit was closed at closing of the magnetizing cur- occasions. In 1860 he was captured by Queen rent. There is thus no thermal action during the Isabella's forces, and was only saved from variable period of closure. Lastly, the heat was death by the clemency of the Queen. On that smaller when the circuit of the second spiral, dur; occasion, he wrote a letter to the Queen, in ing the opening of the inducing circuit, was closed; which he promised never again to take part in it went down as much as the half, “ It thus proved that the production of the magnetic heat takes place any movements against her; but, nevertheless

, during the opening of the voltaic circuit; conse he fought in the Carlist War against her son, quently, that it accompanies the disappearance of Don Alfonso. Don Carlos appointed him in magnetism in the core.''

1873 captain-general of the Carlist forces, and The decrease of heat in this last case is ex- Minister of War. He conducted the operations plained on the principle of thermo-dynamics. of the Carlist forces against Bilbao, and the The disappearance of the magnetism is the defense of the line of Sommorastra, in 1874, cause of the appearance of a certain quantity and, when the Carlists were repulsed there, of heat. When no circuit is near, in which an he resigned his position, but remained with the induced current can arise, then the whole of army. this heat appears in the core; but, when induc

EXGINEERING. The art of engineering tion occurs, a part of the heat appears in the has made great strides in late times, and, with induced circuit, and the rest remains in the the growth of commerce, has been put more core. The cessation of the magnetization is and more into requisition to devise and conan operation in which the magnetic energy de- struct shorter and easier avenues of communicreases and is transformed into heat-energy, cation. In all progressive countries gigantic either in the core or in the neighboring masses works are constantly in progress, requiring which are in a position to be the seat of in- millions of outlay and years of labor, while duction phenomena.

still greater undertakings are being seriously Improved Electric Railway-Signal.—A sim- proposed, such as would formerly have been ple and effective application of electricity to considered fond and idle dreams. Among railroad signaling is in use on the Boston, them may be mentioned the connection of the Lowell & Nashua Railroad. The apparatus is Black Sea with the Caspian by a ship-canal; described and illustrated with a woodcut in the the construction of an artificial channel beScientific American. Its principle will be tween the great rivers of Central Africa, so readily understood from what follows: A sin- as to make a navigable water-way across the gle-cell Calland battery is connected to the two continent; the cutting of a passage between rails at one end of a given section of the line the sea and the low bed of the great African (say two miles in length), each section being Desert, by which a great portion of the sandy insulated from adjoining sections. At the other waste would be submerged, and wide districts end of the section the signal has an electro- rendered fertile; the building of a great shipmagnet similarly connected to the two rails. canal through Southern France from the bay When the circuit is closed, as is normally the of Biscay to the Mediterranean; the widening case, the magnet is excited and the signal and deepening of the Seine, so as to make controlled thereby, so as to show that the Paris a seaport. line is clear. But when a train enters on the It is worthy of note that the chief engineersection, then a shorter circuit is made by the ing projects of the most recent times look wheels' and axles, and the current returns to toward the extension and improvement of the battery by this course instead of passing water-communication. The construction of a through the signals. The magnet ceases now ship-canal through the American Istimus, to attract, and the signal, by mechanical means, which has long been a cherished project of the is at once turned to indicate danger. It is ob- American people, may be said to be on the

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