How to use Spectrum in a sentence
Our eyes are capable of seeing only a narrow spectrum of light.
There is a certain amount of evidence that at any rate in some cases light is necessary, and that the violet rays of the spectrum are chiefly concerned.
Let AoBo be a plane wave-surface of the light before it falls upon the prisms, AB the corresponding wave-surface for a particular part of the spectrum after the light has passed the prisms, or after it has passed the eye-piece of the observing telescope.
There are many thousands of lines in the mercury spectrum, so that from this evidence it would appear that for mercury vapour n ought to be very great, and y almost equal to unity.
Moseley, shortly after the discovery of the diffraction of X-rays by crystals, set to work to examine the X-ray spectrum of a number of elements each of which he made in turn the target of an X-ray tube.Advertisement
A band might in that case fade away towards zero frequencies, and as s increases, return again from infinity with diminishing distances, the head and the tail pointing in the same direction; or with a different value of constants a band might fade away towards infinite frequencies, then return through the whole range of the spectrum to zero frequencies, and once more return with its tail near its head.
The difficulty is further diminished when it is proved, as it can be proved, 2 that the modes of energy represented in the atomic spectrum acquire energy so slowly that the atom might undergo collisions with other atoms for centuries before being set into oscillations which would possess an appreciable amount of energy.
At first he occupied himself with ordinary routine work, but being far from satisfied with the scope which this afforded, he seized eagerly upon the opportunity for novel research, offered by Kirchhoff's discoveries in spectrum analysis.
In the general solar spectrum this element is represented by a large number of lines, but in the spectrum of the prominences and chromosphere one pair only can be detected.
The striking discovery was, in 1903, made by the same investigators that the spontaneous luminosity of radium gives a spectrum of a kind never before obtained without the aid of powerful excitation, electrical or thermal.Advertisement
Sodium is most distinctly recognized by the yellow coloration which volatile salts impart to a Bunsen flame, or, better, by its emission spectrum which has a line (double), the Fraunhofer D, line, in the yellow (the wave-lengths are 5896 and 5890).
The emission spectrum shows two lines, Ka, a double line towards the infra-red, and Ka in the violet.
From 1861 onwards he paid special attention to the solar spectrum.
He was the first, in 1867, to examine the spectrum of the aurora borealis, and detected and measured the characteristic bright line in its yellow green region; but he was mistaken in supposing that this same line, which is often called by his name, is also to be seen in the zodiacal light.
He especially devoted himself to investigations of the radiation of heat from the sun and its absorption by the earth's atmosphere, and to that end devised various delicate methods and instruments, including his electric compensation pyrheliometer, invented in 1893, and apparatus for obtaining a photographic representation of the infra-red spectrum (1895).Advertisement
Its salts are reddish violet in colour, and give a characteristic absorption spectrum.
The salts of praseodymium are green in colour, and give a characteristic spark spectrum.
As the light is twice refracted, the dispersion is increased, and the rays, after transmission through the prism, form a divergent system, which may be allowed to fall on a sheet of white paper, forming the wellknown solar spectrum.
By slightly turning the prism P, the position of the spectrum on the first screen could be shifted sufficiently to cause light of any desired colour to pass through.
Operating on this beam with a second prism, he found that the homogeneous light was not dispersed, and also that it was more refracted the nearer the point from which it was taken approached to the violet end of the spectrum RV.Advertisement
The combined effect of the two is to produce a spectrum sloping up from left to right.
The spectrum will be straight if the twoprismsaresimilar in dispersive property, but if one of them is con structed of a material which possesses any peculiarity in this respect it will be revealed by the curvature of the spectrum.
If we compare the spectrum produced by refraction in a glass prism with that of a diffraction grating, we find not only that the order of colours is reversed, but also that the same colours do not occupy corresponding lengths on the two spectra, the blue and violet being much more extended in the refraction spectrum.
If the increase of the angle of refraction were proportional to the diminution of wave-length for a prism of any material, the resulting spectrum would also be normal.
If the sodium is only gently heated, so as to produce a comparatively rarefied vapour, and a grating spectroscope employed, the spectrum obtained is like that shown in fig.Advertisement
Julius to explain the "flash spectrum" seen during a solar eclipse at the moment at which totality occurs..
If suitable values are chosen for these constants, the formula can be made to represent the dispersion of ordinary transparent media within the visible spectrum very well, but when extended to the infra-red region it often departs considerably from the truth, and it fails altogether in cases of anomalous dispersion.
In this way the existence of bands in the infrared part of the spectrum has been predicted in the case of quartz and detected by experiments on the selective reflection of the material.
He wrote numerous papers on photometry and spectrum analysis in Poggendorff's Annalen and Berichte der k.
Henry Draper's most important contributions to science were made in spectroscopy; he ruled metal gratings in 1869-1870, made valuable spectrum photographs after 1871, and proved the presence of oxygen in the sun in a monograph of 1877.Advertisement
Spectrum analysis thus passed quickly out of the stage in which its main purpose was " analysis " and became our most delicate and powerful method of investigating molecular properties; the old name being no longer appropriate, we now speak of the science of " Spectroscopy."
At present we have still to content ourselves with a much diminished intensity of light when working with gratings, but there is some hope that the efforts to concentrate the light into one spectrum will soon be successful.
The resolving power in the case of gratings is simply mn, where m is the order of spectrum used, and n the total number of lines ruled on the grating.
Opticians should supply sufficient information of the dispersive properties of their materials to allow dµ/dX to be calculated easily for different parts of the spectrum.
If a thickwalled capillary tube is passed over the platinum tube and its length so adjusted that the liquid rises in it by capillary action just above the level of the tube, the spectrum may be examined directly, and the loss of light due to the passage through the partially wetted surface of the walls of the tube is avoided.Advertisement
In consequence the question as to the connexion of the spectrum with the temperature of the gas seems to the present writer to lose some of its force.
When now a small bead of a salt of sodium or lithium is placed in the flame the spectrum of the white hot platinum is traversed by the dark absorption of the D lines.
The efforts which were consequently made in the early days of spectroscopy to discover some numerical relationship between the different wave lengths of the lines belonging to the same spectrum rather disregard the fact that even in acoustics the relationship of integer numbers holds only in special and very simple cases.
Balmer, who showed that the four hydrogen lines in the visible part of the spectrum may be represented by the equation n = A(i - 4/s2), where n is the reciprocal of the wave-length and therefore proportional to the wave frequency, and s successively takes the values 3, 4, 5, 6.
The most complete hydrogen spectrum is that measured by Evershed 8 in the flash spectrum observed during a total solar eclipse, and contains thirty-one lines, all of which agree with considerable accuracy with the formula, if the frequency number n is calculated correctly by reducing the wave-length to vacuo.9 It is a characteristic of Balmer's formula that the frequency approaches a definite limit as s is increased, and it was soon discovered that in several other spectra besides hydrogen, series of lines could be found, which gradually come nearer and nearer to each other as they become fainter, and approach a definite limit.Advertisement
In the case of those elements in which we can represent the spectrum most completely by a number of series, it is generally.
In the case of other metallic groups similar series have also been found, but while in the case of the alkali group nearly the whole spectrum is represented by the combined set of three series, such is not the case with other metals.
In the spectrum of barium no series has yet been recognized.
The spectrum of helium has been very carefully studied by Runge and Paschen.
All its lines arrange themselves in two families of series, in other words, the spectrum looks like that of the superposition of two spectra similar to those presented by the alkali metals.Advertisement
Before leaving the subject, we return for a moment to the spectrum of hydrogen.
Kayser on examining the spectrum recognized the fact that the two series were related to each other like the two branch series, and this was subsequently confirmed.
If we compare Balmer's formula with the general equation of Ritz, we find that the two can be made to agree if the ordinary hydrogen spectrum is that of the side branch series and the constants a', b, c and d are all put equal to zero.'
It seems remarkable, however, that we should not have succeeded yet in reproducing in the laboratory the trunk and main branch of the hydrogen spectrum, if the spectra in question really belong to hydrogen.
According to this view the different lines are given out by different molecules, and we should have to take averages over a number of molecules to obtain the complete spectrum just as we now take averages of energy to obtain the temperature.Advertisement
King, that in the case of the so-called spectrum of cyanogen these tails can be observed.
When we compare together electric discharges the intensity of which is altered by varying, the capacity, we are unable to form an opinion as to whether the effects observed are due to changes in the density of the luminous material or changes of temperature, but the experiments of Sir William and Lady Huggins 1 with the spectrum of calcium are significant in suggesting that it is really the density which is also the determining factor in cases where different concentrations and different spark discharges produce a change in the relative intensities of different lines.
These lines in the case of the spark cannot be due entirely to the increased mass of vapour near the poles, but indicate a real change of spectrum probably connected with a higher temperature.
The method adopted consisted in photographing the spectrum on a film which was kept in rapid motion by being attached to the front of a rotating disk.
Bunsen first announced their discovery, for according to their view every combination of an element showed the characteristic spectrum of its constituent atoms; it did not matter according to this view whether a salt,' e.g.
The experiment proves only the transparency of the gases experimented upon, and this is confirmed by the fact that bodies like bromine and iodine give on heating an emission spectrum corresponding to the absorption spectrum seen at ordinary temperatures.
In many cases there is a considerable difficulty in deciding whether a particular spectrum belongs to a compound body or to one of the elements composing the compound.
There is a vast amount of literature on the subject, but in spite of the difficulty of conceiving a luminous carbon vapour at the temperature of an ordinary carbon flame, the evidence seems to show that no other element is necessary for its production as it is found in the spectrum of pure carbon tetrachloride and certainly in cases where chlorine is excluded.
Another much disputed spectrum is that giving the bands which appear in the electric arc; it is most frequently ascribed to cyanogen, but occasionally also to carbon vapour.
Compounds generally show spectra of resolvable bands, and if an elementary body shows a spectrum of the same type we are probably justified in assuming it to be due to a complex molecule.
These bands appear in the solar spectrum as we observe it, but are due to absorption by the oxygen contained in the atmosphere.
Under different conditions we obtain (a) a continuous spectrum most intense in the yellow and green, (b) the spectrum dividing itself into two families of series, (c) a spectrum of lines which appears when a strong spark passes through oxygen at atmospheric pressure, (d) a spectrum of bands seen in the kathode glow.
Stark discovered that in the case of the series spectrum of hydrogen and of other similar spectra the lines were displaced indicating high velocities; in other cases no displacements could be observed.
No conclusion can therefore be drawn, as Stark' has more recently pointed out, respecting the charge of the molecule which emits the observed spectrum.
As the atomic weight of the haloid increases the spectrum is displaced towards the red.
The most typical case in this respect is the effect of a solvent on the absorption spectrum of a solution.
The chromates of sodium, potassium and ammonium, as well as the bichromates of potassium and ammonium, were found to give the same absorption spectrum.
Nor is the effect of these chromates confined to the blocking out simply of one end of the spectrum, as in the visible part, but two distinct absorption bands are seen, which seem unchanged in position if one of the above-mentioned chromates is replaced by another.
The spectrum of nitrobenzene is also worth comparing with benzene and nitric acid.
The detection of the presence of chlorine or bromine or iodine in a compound is at present undecided, and it may be well that we may have to look for its effects in a different part of the spectrum.
The salts have a faint pink colour, and show a faint absorption spectrum; the spark spectrum is brilliant and well characterized.
He endeavoured, but in vain, to detect any change in the lines of the spectrum of a flame when the flame was acted on by a powerful magnet.
The spectrum shows remarkable peculiarities.
From about 1864 he occupied himself almost exclusively with spectrum analysis, both of stars (Catalogo delle stelle di cui si e determinato lo spettro luminoso, Paris, 1867, 8vo; "Sugli spettri prismatici delle stelle fisse," two parts, 1868, in the Atti della Soc. Ital.) and of the sun (Le Soleil, Paris, 1870, 8vo; 2nd ed., 1877).
Besides the blue and purple of the spectrum he was able to recognize only one colour, yellow, or, as he says in his paper, "that part of the image which others call red appears to me little more than a shade or defect of light; after that the orange, yellow and green seem one colour which descends pretty uniformly from an intense to a rare yellow, making what I should call different shades of yellow."
This slit is set in such a position as to transmit a single line of the spectrum, e.g.
In the case of narrower lines, however, higher dispersion is required to prevent the light of the continuous spectrum on either side of the dark line from blotting out the monochromatic image.
This forms an image of the solar spectrum in its focal plane on the camera slit (1).
On the spectrum see Spectroscopy.
Certain absorption bands at the blue end of the spectrum are supposed to be due to rare elements such as samarium.
The spectrum, also, is very characteristic. The atomic weight, 226.4, places the element in a vacant position in group II.
Its wave-length is probably very near 55'71 tenth-metres, and it is very close to, if not absolutely coincident with, a prominent line in the spectrum of krypton.
By an ingenious method devised by Engelmann, it may be shown that the greatest liberation of oxygen, and consequently the greatest assimilation of carbon, occurs in that region of the spectrum represented by the absorption bands.
After the bacteria had all been brought to rest by being placed in the dark, he threw a spectrum upon the filament, and observed in what region the bacteria first regained their motility, owing to the liberation of oxygen in the process of carbon-assimilation.
The spectrum contains a bright green of wave-length 5351.
In 1868 they noticed in the solar spectrum a bright yellow line which did not correspond to any substance then known, and which they therefore attributed to the then hypothetical element, helium.
This want of proportion in the dispersion for different regions of the spectrum is called the "irrationality of dispersion"; and it is as a direct consequence of this irrationality, that there exists a secondary spectrum or residual colour dispersion, showing itself at the focus of all such telescopes, and roughly in proportion to their size.
The only way in which the secondary spectrum can be reduced still further is by the employment of three lenses of three different sorts of glass, by which arrangement the secondary spectrum has been reduced in the case of the Cooke photo visual objective to about I/loth part of the usual amount, if the whole region of the visible spectrum is taken into account.
The Aµ from C to F being taken as unity in each case then the AA's for the other regions of the spectrum are expressed in fractions A A (C to F) and are given under the asterisks.
Hence it is clear that if the two positive lenses of equal curvature power of o 60 and 0.102 respectively are combined with a negative lens of light flint o 569, then a triple objective, having no secondary spectrum (at any rate with respect to the blue rays), may be obtained.
It was discovered in 1875 through its spectrum, in a specimen of zinc blende by Lecoq de Boisbaudran (Comptes rendus, 1875, 81, p. 493, and following years).
Gallium is best detected by means of its spark spectrum, which gives two violet lines of wave length 4171 and 4031.
Stars having this type of spectrum are always variable, and a large proportion of the more recently discovered long-period variables have been detected through their characteristic spectrum.
If both the bodies are luminous, especially if they do not differ much in brilliancy, the motion of revolution is shown by a periodic doubling of the lines of the spectrum; when one body is moving towards us and the other away their spectral lines are displaced (according to Doppler's principle) in opposite directions, so that all the lines strong enough to appear in both spectra appear double; when the two bodies are in conjunction, and therefore moving transversely, their spectra are merged into one and show nothing unusual.
More usually, however, only one component is sufficiently luminous for its spectrum to appear; its orbital motion is then detected by a periodic change in the absolute displacement of its spectral lines.
That the effect is due to a real difference in the character of the light from the two components has been shown by spectrum analysis, but it is probably exaggerated by contrast.
The spectrum consists of of a continuous band of light crossed by a greater or Spectra .
The spectrum, which closely resembles that of a sunspot, is marked by flutings or bands of lines sharply bounded on the violet side and fading off towards the red.
Finally, a fifth type has been added, the Wolf-Rayet stars; these show a spectrum crossed by the usual dark lines and bands, but showing also bright emission bands of blue and yellow light.
The spectroscope only yields information about the thin outer envelope of the star; and even here elements may be present which do not reveal themselves, for the spectrum shown depends very greatly on the temperature and pressure.
In this connexion it may be noted that the spectrum of Nova Persei, after passing through a stage in which it resembled that of a planetary nebula, has now become of the Wolf-Rayet type.
The group consisting of five stars of Ursa Major together with Sirius has already been alluded to; another very marked group of 16 stars in Perseus, all of the Helium type of spectrum, form a similar association.
For example, the condition for achromatism (4) for two thin lenses in contact is fulfilled in only one part of the spectrum, since do /dn 1 varies within the spectrum.
Fraunhofer, who defined the colours by means of the dark lines in the solar spectrum; and showed that the ratio of the dispersion of two glasses varied about 20% from the red to the violet (the variation for glass and water is about 50%).
In uniting three colours an " achromatism of a higher order " is derived; there is yet a residual " tertiary spectrum," but it can always be neglected.
The name tarsier refers to the great elongation of two of the bones of the tarsus, or ankle, and spectrum to the huge goggle-like eyes and attenuated form which constitute two of the most distinctive features of this weird little creature.
Engelmann showed, for instance, that these red-purple bacteria collect in the ultra-red, and to a less extent in the orange and green, in bands which agree with the absorption spectrum of the extracted colouring matter.
As is shown by his verses and sometimes by his prose, his mind was highly imaginative; the poet Coleridge declared that if he "had not been the first chemist, he would have been the first poet 1 Davy's will directed that this service, after Lady Davy's death, should pass to his brother, Dr John Davy, on whose decease, if he had no heirs who could make use of it, it was to be melted and sold, the proceeds going to the Royal Society" to found a medal to be given annually for the most important discovery in chemistry anywhere made in Europe or Anglo-America."The silver produced £736, and the interest on that sum is expended on the Davy medal, which was awarded for the first time in 1877, to Bunsen and Kirchhoff for their discovery of spectrum analysis.
He can scarcely be called its inventor, for not only had many investigators already used the prism as an instrument of chemical inquiry, but considerable progress had been made towards the explanation of the principles upon which spectrum analysis rests.
Kirchhoff in announcing that the lines of the spectrum were characteristic of the chemical substance which emitted them, and in indicating the value of this discovery in chemical analysis.
According to Hittorf he was the first who saw the three lines of the hydrogen spectrum, which a few months after his death were recognized in the spectrum of the solar protuberances, and thus solved one of the mysteries of modern astronomy.
Lithium is detected by the faint yellow line of wave-length 6104, and the bright red line of wave-length 6708, shown in its flame spectrum.
This is not strictly the case, however, for such gases and vapours as exhibit well-defined bands of absorption in the spectrum, as these bands are altered in character by compression.
The solution is moderately transparent for a large number of rays in the neighbourhood of the green part of the spectrum; it is, on the whole, much more opaque for red rays, but is readily penetrated by certain red rays belonging to a narrow region of the spectrum.
The results of his labours may be found in the elaborate Photographic Map of the Normal Solar Spectrum (1888) and the Table of Solar Wave-Lengths (1898).
They have lost completely the gaseous characteristic of producing a line spectrum, and radiate like incandescent solids.
The surface region which yields a continuous spectrum is called the photosphere; it possesses optically a sharp boundary, which is generally a perfect sphere, but shows occasionally at the rim slight depressions or more rarely elevations.
Enclosing the photosphere is a truly gaseous envelope which is called the chromosphere, and which shows a spectrum of bright lines when we can isolate its emission from that of the photosphere.
The radiations from the sun must be considered in two parts, corresponding respectively to the continuous spectrum and the line-spectrum.
It is then found both by experiment and by thermodynamic theory that in these amorphous radiations there is for each temperature a definite distribution of the energy over the spectrum according to a law which may be expressed by 0 5 0(OX)dX, between the wave-lengths X, A+dX; and as to the form of the function 4), Planck has shown (Sitzungsber.
It will be seen that the maximum ordinates lie upon the curve A9 = constant dotted in the figure, and so, as the temperature of the ideal body rises, the wave-length of most intense radiation shifts from the infra-red X towards the luminous part of the spectrum.
P. Langley in 18 93 at Mount Whitney in California (14,000 ft.), with the bolometer, an exceedingly sensitive instrument which he invented, and which enabled him to feel his way thermally over the whole spectrum, noting all the Constant.
The continuous spectrum leads to no inference, except that of the temperature of the central globe; but the multitude of dark lines by which it is crossed reveal the elements composing pe ct rum o the truly gaseous cloaks which enclose it.
Paschen in 1896 identified an unmistakable oxygen triplet in the infra-red, which is shown terrestrially only in the vacuum tube, where the spectrum is very different from that of atmospheric absorptions.
The absence of lines of the spectrum of any element from the solar spectrum is no proof that the element is absent from the sun; apart from the possibility that the high temperature and other circumstances may show it transformed into some unknown mode, which is perhaps the explanation of the absence of nitrogen, chlorine and other non-metals; if the element is of high atomic weight we should expect it to be found only in the lowest strata of the sun's atmosphere, where its temperature was nearly equal to that of the central globe, and so any absorption line which it showed would be weak.
The spectrum taken near the limb of the sun shows increased general absorption, but also definite peculiarities of great interest in connexion with the spectra of the spots, which it will be convenient to describe first.
This is not a uniform shade over the whole length of the spectrum, but shows in bands or flutings of greater or less darkness, which in places and at intervals have been resolved by Young, Duner and other unquestionable observers into hosts of dark lines.
Besides this the spectrum shows very many differences from the mean spectrum of the disk, the interpretation of which is at present far from clear.
If the spot spectrum is compared with that of the chromosphere it appears that the lines of most frequent occurrence in the latter are those least affected in the spot, and the high level chromospheric lines not at all; the natural interpretation is that the spot is below the chromosphere.
The band spectrum, which corresponds to the compound or at least to the molecule of titanium, certainly belongs to a lower temperature than the line spectrum of the same metal.
Hence when the photosphere is viewed through it an absorption spectrum is shown, but when it can be viewed separately a bright line spectrum appears.
In the higher chromosphere on occasions metallic gases are carried up to such a level that without an eclipse a bright line spectrum of many elements may be seen, but it is always possible to see those of hydrogen and helium, and by opening the slit of the spectroscope so as to weaken still further the continuous spectrum from the photosphere (now a mere reflection) the actual forms of the gaseous structures called prominences round the sun's rim may be seen.
In the visual spectrum there are four hydrogen lines and one helium line in which the actual shapes may be examined.
The helium formations do not reach the sun's limb, and it is another puzzling detail that the spectrum of the disk shows no absorption line of anything like an intensity to correspond with the emission line of helium in the chromosphere.
The eruptive prominences, called also metallic, because it is they which show at their bases a complete bright line spectrum of the metallic elements, rush upwards at speeds which it is difficult to associate with transfers of matter; the velocity often exceeds loo m.
The pressure which produces a continuous spectrum in gases at a temperature of 6000 0 must be very great.
For example, in the iron spectrum three groups about wave-length 4500 are found by Duffield to be displaced respectively 0-17, 0.34, 0.66 tenth-metres, at 100 atmospheres.
Though few follow him so far, an explanation of the principle will make it clear that there are numerous possible opportunities for anomalous dispersion to qualify inferences from the spectrum.
Omitting extreme examples, like fuchsin, where the spectrum is actually cut in two, it is of more general importance to detect the phenomenon in the ordinary absorption lines of the metallic elements.
Puccianti, who measured it by the interferometer in the case of more than a hundred lines of different metals; he found its degree to differ much in different lines of the same spectrum.
In calcium, for instance, the g line shows in the laboratory much stronger anomalous dispersion than H and K; but in the solar spectrum H and K are broad out of all comparison to g.
Some of his opponents denied the truth of his experiments, refusing to believe in the existence of the spectrum.
Others criticized the experiments, saying that the length of the spectrum was never more than three and a half times the breadth, whereas Newton found it to be five times the breadth.
It appears that Newton made the mistake of supposing that all prisms would give a spectrum of exactly the same length; the objections of his opponents led him to measure carefully the lengths of spectra formed by prisms of different angles and of different refractive indices; and it seems strange that he was not led thereby to the discovery of the different dispersive powers of different refractive substances.
Thousands of the dark lines in the solar spectrum agree absolutely in wave-length with the bright rays artificially obtained from known substances, and appertaining to them individually.
Its distinctive method is spectrum analysis, the invention and development of which in the 19th century have fundamentally altered the purpose and prospects of celestial inquiries.
The Indian eclipse of the 18th of August 1868 supplied knowledge of their spectrum, found to include the yellow ray of an exotic gas named by Sir Norman Lockyer " helium."
Young caught the " flash spectrum " of the reversing layer, at the moment of second contact, at Xerez de la Frontera in Spain, on the 22nd of December 1870.
Nebular chemistry was initiated by the same investigator when, on the 29th of August 1864, he observed the bright-line spectrum of a planetary nebula in Draco.
Again by Sir William Huggins, the spectrum of the Orion nebula was photographed on the 7th of March 1882; and the method has gradually become nearly exclusive in the study of nebular emanations.
A photograph of the spectrum of Tebbutt's comet, taken by him on the 24th of June 1881, showed radiations of shorter wave-lengths but identical source, and in addition, a percentage of reflected solar light marked as such by the presence of some well-known Fraunhofer lines.
When, in the third quarter of the igth century, spectrum analysis was applied to the light coming to us from the heavenly bodies, a new era in astronomical science was opened up of such importance that the body of knowledge revealed by this method has sometimes been termed the "new astronomy."
Even in a liquid form, the spectrum of any kind of matter is less characteristic than that of gas.
Moreover, a gaseous body of uniform temperature, and so dense as to be non-transparent, does not radiate the characteristic spectrum of the gas of which it is composed.
When the spectroscope was first applied in astronomy, it was hoped that the light reflected from living matter might be found to possess some property different from that found in light reflected from non-living matter, and that we might thus detect the presence of life on the surface of a planet by a study of its spectrum; but no hope of this kind has so far been realized.
We have, in this brief view of the subject, referred mainly to the results of spectrum analysis.
The true character of the light in this case may be revealed by analysing it with a spectroscope, when a spectrum is obtained traversed by dark bands corresponding to the constituents that are weakened or annulled.
Arago pointed out, by supposing that in passing through the plate the plane of polarization of each monochromatic constituent is rotated by an amount dependent upon the frequency - an explanation that may be at once verified either by using monochromatic light or by analysing the light with a spectroscope, the spectrum in the latter case being traversed by one or more dark bands, according to the thickness of the plate, that pass along the spectrum from end to end as the analyser is rotated.
Upsala, however, is a place where the auroral spectrum can often be observed in the sky, even when no aurora is visible, and it has generally been believed that what Angstrom really saw was an auroral and not a zodiacal spectrum.
Wright, of New Haven, also made careful observations leading to the conclusion that the spectrum differs from sunlight only in intensity.
He was unable to see any marked deviation of the spectrum from that of the sun; but it does not appear that either he or any other of the observers distinctly saw the dark lines of the solar spectrum.
For example, the real image may be recorded on a photographic plate; it may be measured; it can be physically altered by polarization, by spectrum analysis of the light employed by absorbing layers, &c. The greatest advantage of the compound microscope is that it represents a larger area, and this much more completely than is possible in the simple form.
If the obliquity of illumination be so great that the principal maximum passes through the outermost edge of the objective, while a spectrum of 1st order passes the opposite edge, so that in the back focal plane the diffraction phenomenon shown in fig.
If now the spectrum of Est order of the larger division be cut out from the diffraction figure, as is shown in fig.
In systems employed for visual observation (to which class the microscope belongs) the red and blue rays, which include the physiologically most active part of the spectrum, are combined; but rays other than the two selected are not united in one point.
By using these glasses and employing minerals with special optical properties, it is possible to correct objectives so that three colours can be combined, leaving only a quite slight tertiary spectrum, and removing the spherical aberration for two colours.
In this, the secondary spectrum is so much lessened that for all practical purposes it is unnoticeable.
The chief cone of rays then enters obliquely into the objective, the angle between the direct cone of rays and the diffraction spectrum of the first order can then become as large again as with direct lighting, and still be taken up in the objective.
A broad spectrum of lighting effects allows them to offer the most competitive value for lighting in the industry.
She was of the opinion that sensible legislation would be welcomed across the spectrum and hasty decisions would only bring anguish.
All the crude extracts and the fractions exhibited a very good level of broad spectrum antibacterial activity.
Silver is a broad spectrum antimicrobial that helps to prevent infection.
The response file used to generate the arf is written in the spectrum in the keyword RESPFILE.
The code is currently at beta... asp - amiga SPectrum emulator aSp is a Sinclair ZX Spectrum Emulator for the amiga.
Anne Church a personal assistant also from Ashworth who suggested color themes through the whole spectrum for the Ashworth Center.
Case study examples will be chosen across the whole spectrum of agricultural biotechnology.
There is an extender PCB which fits on to the Spectrum and a ribbon cable to the keyboard.
The problem is that the Spectrum ROM handles this line interpretation as an arithmetic calculation, and calls its calculating routines.
A first- or second-generation cephalosporin has the required spectrum of activity.
Antibiotic rationale A third-generation cephalosporin has the required spectrum of activity against the majority of likely pathogens and is an appropriate initial choice.
It burns with a brilliant blue flame - the name cesium derives from the sky-blue lines in its spectrum.
For example, the Spectrum allows multiple program lines with each program line, separated by a colon.
We also used a spectrum analyzer to show the coloration.
Other people are very happy, and further down the spectrum, other people are what we may say suffering from mild contentment.
Kirchhoff's second law A low-density gas will radiate an emission-line spectrum with an underlying emission continuum.
In the wavelet spectrum that follows, an exact n FFT is used for the CWT's fast convolution.
Sinclair also said that about the Spectrum but immediately countermanded the idea by producing a range of games programs.
Film director David Cronenberg was the world's first cyborg - being half human, half Spectrum 48k.
Here is the spectrum of cytochrome c. The absorption pattern for all three cytochrome c. The absorption pattern for all three cytochromes changes markedly when these molecules are oxidized and reduced.
At the extreme end of the spectrum, people can find themselves clinically depressed or even suicidal.
Project Spectrum Project Spectrum offers an alternative approach to assessment and curriculum development for the preschool and early primary years.
A broad spectrum, proven activity disinfectant should be used.
The broad spectrum disinfectant Virkon S meets the needs.
Can children with autistic spectrum disorders perceive affect in music?
The family of electromagnetic waves from the high-frequency gamma rays to the relatively low-frequency radio waves forms what is called the electromagnetic spectrum.
While control of the entire electromagnetic spectrum is impossible, key portions must be commanded at the right time.
To alleviate such difficulties, it is common to assume a uniform emissivity over the entire wavelength spectrum.
The Spectrum Emulator games cd a Spectrum emulator games cd a Spectrum Emulator CD with 3000 games.
These can be estimated in a way similar to the power spectrum, but more data is usually needed to get reliable estimates.
Palestine is now a key fault line in US imperialism's effort to establish ' full spectrum dominance ' around the world.
Why does the spectrum tick every fiftieth of a second?
Positioned in railroad stations, airports and hotels, all payphone sites have a high consumer footfall ensuring that Spectrum sees ongoing healthy traffic.
They searched harder and dug heavier for tracks on this second volume, with a musical spectrum spanning from raw funk to gritty soul.
Spectrum Micro Neck gaiter Simple lightweight neck gaiter, ideal for general outdoor use.
Her angelic vocals transcend musical genres, giving her fans from all sides of the music spectrum.
Weiser defines a spectrum of access ranging from open to closed, with various gradations in between.
A total of 24 sources were observed with one or both transmission grating spectrometers, from which 19 gave a useful spectrum.
This is the spectrum of myoglobin, a mostly helical protein.
The more reliable narrow spectrum hydrometer gave a reading of 1.026 which actually would mean a saline figure of 35.
They play a key role in the delivery of the spectrum of care needed by mentally ill people.
The amber color reduces the spectrum of light that the flying insects can see, thus sending them to a brighter source of light.
Further suppose that spectrum inversion does not in fact occur.
Urea is the main form in which nitrogen is excreted in mammals UV radiation invisible rays that are part of the electromagnetic spectrum.
Data is also collected on the spectrum of organisms isolated from cases of fungal keratitis.
The light source was a halogen lamp used in the dental clinic, emitting mainly in the blue part of the spectrum.
Domestic tungsten - Domestic tungsten lighting has a strong yellow/orange cast, because its color spectrum is shifted toward stronger wavelengths.
When a gas is heated or a large electric current is passed through it, the gas emits a characteristic line spectrum.
The success with control of the hibiscus mealybug has served to sensitize a wide spectrum of the public about biological control.
Exercise You are provided with a spectrum of a compound (identified with a letter) having the molecular formula C 6 H 14.
All of these added up to a rather motley spectrum and to an ambivalent score.
Photonics Focus dropped into a session where speakers approached diffractive optics from extreme ends of the power spectrum.
The nominal TiO in the X-ray photoelectron spectrum (XPS) upon which they rely heavily has almost certainly suffered surface oxidation.
The color of light A glass prism will split white light into a spectrum of colors.
An AR spectrum's peaks are not linearly proportional to power.
Preliminary evidence suggests increased activity of a broad spectrum cysteine protease.
Our findings are discussed with respect to previous works on the spectrum of energetic protons in the 10 MeV to GeV energy range.
Almost one quarter of these are members of a previously unknown class of X-ray bright, flat spectrum, radio-loud quasars.
The station will also be on air in Germany as it has secured space on the German digital radio spectrum.
At a stroke MVNO could remove the absolute barrier to entry arising from the finite available radio spectrum.
The company was one of the first to manufacture an independent 16K ram pack for the Spectrum.
These approaches combined show a potential way out of the current artificially created resource scarcity of spectrum.
As a result, the low-frequency radio emission is affected by synchrotron self-absorption, giving cores a characteristically flat radio spectrum.
On the other end of the spectrum, " Ride With Me " displays an almost breezy pop sensibility.
The spectrum contains just one component, at 256 Hz, because the pure tone is a single sine wave.
The Spectrum Any sound can be constructed by adding up enough sine waves of differing intensity levels, frequencies and starting times.
Visitors can enjoy a wide spectrum of activities and a great number of museums and archeological sites.
Objectives To share issues and methodologies in language and identity across the spectrum of applied linguistics, including sociolinguistics.
The label designer encompasses a very broad spectrum of different mediums for John Rocha.
During the two days of this conference, expert speakers from all quarters will span the spectrum of system criticality.
Steve's address covered a wide spectrum ranging from the events of September 11th to the virtues of the internet.
The enemy can use his vision across a broad band of the electromagnetic spectrum.
Oliver advises on a broad spectrum of company law matters.
More often people to find it helpful make sense of their experiences in light of the autistic spectrum.
We have a wide spectrum of runners which start with people who just want to jog all the way through to top club athletes.
Our century has seen the entire electromagnetic spectrum opened for business.
I just translate that effect from a sound spectrum into a visible eye spectrum.
Health visitors advise on ASD Our recent pieces on autism spectrum disorders have generated much response.
The cobalt is still Co 2+ as evidenced by the crystal field splitting of the Co L-edge peak in the absorption spectrum.
Only by making better use of the radio spectrum can the visions be achieved.
Road traffic noise is variable and the frequency spectrum itself is not ideal for masking speech.
This thickness is then used in the analysis of the X-ray spectrum to correct for self absorption of X-rays in the sample.
Intended for amateur radio operators, the book also gives instructions for smaller projects such as simple frequency synthesizer and spectrum analyzer.
Hood in dove gray unlined, edged with Spectrum blue taffeta with a thin gold cord sewn to the leading edge of the hood.
It could possibly be hypothecated taxation from spectrum receipts.
Striking graphics confusing ANYONE who has seen 3-D Tunnel will find Vortex for the 16K Spectrum familiar.
While top-end and mid-range are handled well, once again however the lower ends of the sound spectrum are left sadly unplumbed.
The presence or absence of expression of these splice variants is being documented in normal tissues and a spectrum of brain tumors.
The colors are ordered in the spectrum in the sequence red, orange, yellow, green, blue, indigo, violet.
Hartford's spectrum basic a boston car heights insurance simple measure boththe zephyr xport then again blue.
About the colour there can be no prima facie difficulty; for, as soon as the question is raised, it is seen that the standard of linear dimension, with reference to which the particles are called small, is the wave-length of light, and that a given set of particles would (on any conceivable view as to their mode of action) produce a continually increasing disturbance as we pass along the spectrum towards the more refrangible end.
Vogel and his successors employed one or other form of measuring machine, provided with a microscope having single or close parallel webs which could be successively pointed on the photographed lines of the star spectrum and the lines of the terrestrial spectrum.
Descartes regards matter as uniform in character throughout the universe; he anticipates, as it were, from his own transcendental ground, the revelations of spectrum analysis as applied to the sun and stars.
The spectrum of helium as observed in a discharge tube is distinguished by a moderate number of brilliant lines, distributed over the whole visual spectrum.
The rays of the visible spectrum do not supply all the energy which the plant obtains.
The atomic weight of the element was determined by C. Winkler by analysis of the pure chloride GeCl4, the value obtained being 72.32, whilst Lecoq de Boisbaudran (Comptes rend us, 1886, 103, 45 2), by a comparison of the lines in the spark spectrum of the element, deduced the value 72.3.
He showed that in the spectra of the fixed stars many of the dark lines were different from those of the solar spectrum, whilst other wellknown solar lines were wanting; and he concluded that it was not by any action of the terrestrial atmosphere upon the light passing through it that the lines were produced.
His name is especially associated with two main branches of investigation - aeronautics, and the exploration of the infra-red portions of the solar spectrum.
He found that his crystal-grating gave a spectrum of two lines for each element and that their frequency increased by definite steps ashepassed from one element to the next; indeed, the frequency of vibration associated with each element was a simple function of a number which he found to be identical with the atomic number.
In a diffraction spectrum the diffraction is proportional to the wavelength, and the spectrum is said to be "normal."
It is no doubt important to recognize that the two types of spectra seem to represent two extreme cases of one formula, the significant difference being that in the line spectrum the distance between lines diminishes as we recede from the head, while in the case of the band it increases, at any rate to begin with.
Further, he showed that the spectrum of a dense ignited gas resembles that of an incandescent liquid or solid, and he traced a gradual change in the spectrum of an incandescent gas under increasing pressure, the sharp lines observable when it is extremely attenuated broadening out to nebulous bands as the pressure rises, till they merge in the continuous spectrum as the gas approaches a density comparable with that of the liquid state.
For relatively short focal lengths a triple construction such as this is almost necessary in order to obtain an objective free from aberration of the 3rd order, and it might be thought at first that, given the closest attainable degree of rationality between the colour dispersions of the two glasses employed, which we will call crown and flint, it would be impossible to devise another form of triple objective, by retaining the same flint glass, but adopting two sorts of crown instead of only one, which would have its secondary spectrum very much further reduced.
The spectrum is of the third type with bright hydrogen emission lines (see below, Spectra of Stars).
Most of the metallic vapours that produce this lie too close to the photosphere for the separation to be made except during eclipses, when a flash spectrum of bright lines shines out for, say, five seconds after the continuous spectrum has disappeared, and again before it reappears (see Eclipse).
It would apply only if the spectrum had no infra-red and ultraviolet extensions.
We offer a selection of high quality, purified genomic DNA suitable for a wide spectrum of genetic research applications.
An example of this can be seen in the spectrum of the most distant quasar currently known.
The company was one of the first to manufacture an independent 16K RAM pack for the Spectrum.
A set of motion energy receptive fields is designed in order to sample the power spectrum of a moving texture.
The recording of the spectrum and redshift of this object is noteworthy in itself.
The book covers a wide spectrum of approaches from Bach flower remedies to reminiscence therapy.
The explanations given for spectrum multiplexing are unclear, and seem to be delivered by rote without any understanding.
If it is 2-D, then each spectrum will be scrunched according to the corresponding cross-section of the wavelength array.
Steve 's address covered a wide spectrum ranging from the events of September 11th to the virtues of the internet.
The spectrum analyzer is to be assembled on a satellite on Polar orbit 700 km above the surface of the Earth.
I have a special interest in working with adults with autistic spectrum disorder.
Using this function on a time signal has the feel of plugging in a spectrum analyzer.
Better to use a low output Tesla coil, which generates high voltage splattered all over the RF spectrum.
Is there a machine code routine which simulates sprite graphics on the Spectrum?
The approach is to estimate the power spectrum of the clean speech by subtracting the noise spectrum from the noisy speech spectrum.
Use a broad spectrum sunscreen with an SPF of 15 or above.
Now we have technologies we can use to explore the terahertz region of the spectrum, said Professor Davies.
During the second clonic phase, the relative power spectrum of theta frequency was higher than that before stunning.
Dynamic variations in frequency spectrum are known to have an important effect on the timbre of sounds.
The game is at the Guildford Spectrum Arena on Thursday 15th September with tip-off at 8.00 pm.
Students will explore the particular learning styles of pupils with autism spectrum disorders, taking into consideration the triad of impairments.
Below, you will see the spectrum of the Sun at ultraviolet wavelengths.
This cassette contains five of the most uninspired games ever to disgrace the Spectrum.
However, no attempt has been made to estimate the groundwater travel time spectrum for the unsaturated zone of the Chalk.
What is being discussed is how to utilize the spectrum more efficiently.
A false color image is generated from the EDX maps by assigning the visible spectrum to a suitable band of X-ray energies.
The global wavelet spectrum, which is similar to a smoothed FFT, is given by using the full time range.
Hartford 's spectrum basic a boston car heights insurance simple measure boththe zephyr xport then again blue.
At the other end of the size spectrum are photo frames with the baby's first name and birth date engraved into them.
Use your newborn's weight as a guide; you'll want to move up to the next size as his or her weight approaches the larger end of the spectrum.
Or on the other spectrum, you might feel like any old piano will do.
Some phones offer spread spectrum features.
Basically, the spread spectrum increases the security of the phone to help keep unauthorized listeners off the phone.
A new television can cost over $1,000 at the low end of the spectrum.
This tablet comes in black only and is on the higher end of the tablet pricing spectrum, retailing at around $3,000.
On the other end of the spectrum are those people who actually look for free kittens to feed to snakes, use as bait for dog fights or sell for a profit to laboratories.
Cats aren't able to see colors in the red spectrum the same way we do.
On the other end of the spectrum are those that believe homemade is best.
Age is a factor, especially for the young and seniors, as they are both on the wrong end of the spectrum.
At the other end of the spectrum, large wind turbines can produce great amounts of electricity and are often set up in clusters known as wind farms.
The Paris collections cover the entire spectrum of traditional through contemporary, always building upon trends from the years before.
The gold and yellow color spectrum is another popular range of colors.
To help make the most of your small space, keep the colors on the cooler end of the spectrum.
Colors can run the temperature spectrum from one end to the next, so don't feel that if you love the color green, but have a large kitchen, that it won't work.
Purple falls on the far end of the blue spectrum and can be used as an accent color, just as red, pink, yellow, or green.
While it tends to showcase homes at the more expensive end of the spectrum, it provides plenty of inspiration and advice to create the same looks in your own home.
On the light end of the spectrum, there is the bright but light Robin's Egg and the cool and gray-hinted Wedgewood.
Some cost money, and others are free - with the hope you will purchase a full spectrum of makeup once you see how beautiful your face looks after new makeup has been applied.
This gorgeous spectrum of colors is further enhanced by not being tested on animals, which is a fact that many cosmetic companies cannot claim.
Green eyes should try plums and brown can go to either end of the spectrum.
Iredale products are water-resistant, non-comedogenic, naturally anti-inflammatory and contain broad spectrum sun protection.
The minerals are refined to a dust-like substance, and the products contain broad spectrum sun protection and are free of irritants like dye, oil, talc, alcohol and perfume.
The colors are less on the orange side of the spectrum and more brownish-beige, with hints of gold and champagne to soften them up.
Bronzed Gold certainly performs well on its own, thanks to its remarkable color, but the cream is especially nice when worn as a base beneath shadows across the color spectrum (think turquoise and green for summer).
Brown Sugar is a delightful pinkish-brown shade that tends to fall more on the nude end of the spectrum.
With over 125 eye shadows, 100 lipsticks and a broad spectrum of products for body painting and special effects, the line has over 1400 quality products available for beauty professionals as well as the average cosmetic consumer.
Redheads should always stick to either side of the color spectrum, rather than in the middle.
Knowing that black women's skin tones run the full gamut of the color spectrum, Fashion Fair has long offered women of all complexions quality cosmetics designed to bring out their beauty.
Two of the colors (Painkiller and Flash) are exceptionally bright, while the rest of them are on the lower-key end of the spectrum.
The special spectrum of colors and metallic shimmers make a fashion statement that carries the Twilight saga from the screen into everyday culture.
Make sure you choose three colors that are in the same color spectrum such as all browns, purples, grays, or blues.