scholarly journals III. On the atmospheric lines of the solar spectrum, illustrated by a map drawn on the same scale as that adopted by Kirchhoff

1875 ◽  
Vol 165 ◽  
pp. 157-160
Keyword(s):  
Rainy Season ◽  
Royal Society ◽  
General Procedure ◽  
Solar Spectrum ◽  
The Other ◽  
The Sun ◽  
Single Group ◽  
Short Period ◽  
Clear Atmosphere ◽  
Do So

The spectroscopic observations hereafter discussed were made with instruments belonging to the Royal Society, and in accordance with certain suggestions which a Committee were good enough to make in connexion with my letter to Sir Edward Sabine, President, dated 13th February, 1866. In view of my residence at a considerable height, and the exceedingly clear atmosphere prevailing at some periods of the year, it was suggested that the locality was peculiarly favourable for comparing the solar spectrum when the sun was high with the corresponding spectrum at sunset; any differences between these aspects which might appear were to be noted on Kirchhoff’s well-known maps. Accordingly I set to work with the spectroscope first supplied to me (hereafter distinguished by the prefix old ), and during the autumns of 1868 and 1869 I mapped the differences in question from the extreme red to D: these results appeared in the ‘Proceedings of the Royal Society,’ No. 123, 1870, the Map being marked vol. xix. pl. 1; it is unnecessary, therefore, to dwell on this portion of my labours, excepting to add that the definitions and general procedure there adopted have been retained in the remarks which follow. 2. The observations hereafter noticed were always taken in the autumn , when, the rainy season having passed away, the atmosphere on these mountains is exceedingly clear, so that the sun, the object of inquiry, is bright even to his setting, and a spectrum may therefore be then obtained through a long stretch of terrestrial atmosphere corresponding to the height of the station of observation; on the other hand, with the sun about the meridian, the height of station places the observer above a relative amount of atmosphere, so that the spectrum obtainable at this time and about sunset are highly eligible for the comparison in view. Accordingly the two spectra are given in the accompanying map (Plate 25); and for easy comparison they are placed in juxtaposition. By “sun high” is to be understood any position for the sun within a couple of hours of the meridian; by “sun low” that the sun was within 3 or 4 diameters of his setting and yet quite bright. Indeed it is only when very near sunset that the marked alterations in the lines appear; so that the spectrum required is not only rarely obtainable, but it hardly lasts beyond 10 minutes of an evening. In this short period (when, moreover, the observer is fatigued with previous watching) changes from the sun-high spectrum must first be detected; then their position must be identified, and, failing this, found by measurement; next, the appearance should be drawn, and finally the drawing should be compared with the original: under these conditions a week may be easily absorbed by a single group. It is also to be borne in mind that no human eye will endure, without at least temporary injury, protracted watching of the bright solar spectrum for more than four or five weeks at a time; indeed, though I habitually used both eyes as a relief to one another, they both invariably suffered, and continued to do so for several weeks after every autumn. The following facts may be here mentioned:—

scholarly journals II. On the atmospheric lines of the solar spectrum, illustrated by a map drawn on the same scale as that adopted by Kirchhoff

1875 ◽  
Vol 23 (156-163) ◽  
pp. 201-202
Keyword(s):  
Sea Level ◽  
Royal Society ◽  
Solar Spectrum ◽  
The Sun ◽  
Atmospheric Absorption ◽  
Spectroscopic Observations ◽  
Clear Atmosphere

The spectroscopic observations described in this paper were made with instruments belonging to the Royal Society, and in accordance with certain suggestions which had been made to the author by a committee appointed in consequence of a letter of his to Sir Edward Sabine, President, dated 13th February, 1866. In view of his residence at a considerable height above the sea-level, and of the exceedingly clear atmosphere prevailing at some periods of the year, it was suggested that the locality was peculiarly favourable for a determination of the lines of the solar spectrum due to atmospheric absorption, and that, for this purpose, the solar spectrum when the sun was high should be compared with the spectrum at sunset, and any additional lines which might appear in the latter case should be noted with reference to Kirchhoff’s map. Accordingly the author set to work with the spectroscope first supplied to him, and in the autumns of 1868 and 1869 mapped the differences in question from the extreme red to D. These results appeared in the 'Proceedings of the Royal Society' for June 16,1870, and the map of the spectra, sun high and sun low, of the region in question forms plate 1 of the 19th volume.

scholarly journals II. Some particulars of the transit of Venus across the Sun, December 9, 1874, observed on the Himalaya Mountains, Mussoorie, at May-Villa Station, Lat. 30° 28′ N., long. 78° 3′. E., height above sea 6765 feet

1875 ◽  
Vol 23 (156-163) ◽  
pp. 254-259
Keyword(s):  
Royal Society ◽  
The Other ◽  
The Sun ◽  
Other Hand ◽  
Time Of Year ◽  
The Himalaya ◽  
Clear Atmosphere ◽  
Himalaya Mountains

Naturally sharing in the great interest excited by the transit of Venus, which occurred this forenoon, I proposed that I should observe the event with the equatoreal of the Royal Society, which Capt. J. Herschel, R. E., in his absence from India, had temporarily placed at my disposal; and the project meeting with liberal support from Col. J. T. Walker, R. E., Superintendent, Great Trigonometrical Survey of India, I was enabled, through his kindness, to provide myself with four chronometers, a good altazimuth, a barometer, thermometers, and other articles of equipment necessary for the undertaking. My especial object in view was to observe the transit from a considerable height ; and this condition was easily secured through the circumstance that I was located only 14 miles from Mussoorie, on the Himalaya Mountains. No doubt a station on these mountains would be very liable to an envelope of mist and cloud at the time of year in question; but, on the other hand, were really good weather to prevail, I should enjoy the advantages of an exquisitely clear atmosphere, such as I have never experienced save on the Himalayas.

scholarly journals IX. On the lines of the solar spectrum

1860 ◽  
Vol 150 ◽  
pp. 149-160 ◽  
Keyword(s):  
Nitrous Acid ◽  
Royal Society ◽  
Solar Spectrum ◽  
Human Vision ◽  
The Sun ◽  
Continuous Line ◽  
Acid Gas ◽  
Principal Lines

In a paper published in the Transactions of the Royal Society of Edinburgh for 1833, Sir David Brewster stated that by various means he had examined the lines of the solar spectrum, and those produced by the intervention of nitrous acid gas, and had delineated them on a scale four times greater than that employed in the beautiful map of Fraunhofer. Some portions also, which were more particularly studied, had been drawn on a scale twelve times greater. "Fraunhofer,” he continued, "has laid down in his map 354 lines, but in the delineations which I have executed, the spectrum is divided into more than 2000 visible and easily recognized portions, separated from each other by lines more or less marked, according as we use the simple solar spectrum, or the solar and gaseous spectrum combined, or the gaseous spectrum itself, in which any breadth can be given to the dark spaces.” None of these drawings, however, were published at the time. Frequent observations were continued during the years 1837, 1838, and 1841; and now, after a lapse of many years, the various delineations, having been collated and arranged by Dr. Gladstone, form the principal diagrams in the Plate accompanying this paper. Fig. 1 of Plate IV. represents the lines observed when the sun was at a considerable altitude above the horizon, and its light was examined by means of a good prism and telescope. The spectrum is delineated on so large a scale that it was necessary to divide it into two portions, the upper diagram representing the part between the least refrangible end and the line designated F 7, the lower diagram the part between F 7 and the most refrangible end. On a comparison with Fraunhofer’s large map, the principal lines and features will be easily recognized; but it will be seen that every portion of the spectrum contains lines wanting in the earlier drawing, and that parts which Fraunhofer has marked by one line are resolved into groups of bright spaces alternating with dark lines. The figure of the spectrum extends at the more refrangible or violet end to about the same distance as that of the Bavarian philosopher, but it exhibits a considerable extension at the red or less refrangible end. The principal lines are indicated by those letters, A, a , B, C, &c., which were assigned to them by him, and the larger intermediate lines are marked by numbers, 1, 2, 3, &c., beginning afresh on the more refrangible side of each letter; so that any one of these may be expressed by a combination of a letter and numeral; as, for instance, C 6, a remarkable line in the orange, of which much will be said hereafter. The extreme violet is lettered, both in this and in a map to be subsequently described, by that continuation of the alphabet which has been adopted by M. Becquerel. It was necessary to indicate in some similar manner the newly published, though not newly discovered, lines at the red end of the spectrum; and as the alphabet has not been appropriated by M. Becquerel beyond P, and it is not likely that further research will largely extend the spectrum in that direction, it was thought safe to take the end of the alphabet, and denoting the first strongly-marked line before A by Z, to work backwards into those slightly refrangible rays, which have been as yet unresolved by human vision. Some of the dark spaces of the spectrum are of an appreciable breadth, in which case they are represented as bands; and where the observation of a line was indistinct or uncertain, it is marked by an interrupted instead of a continuous line.

scholarly journals IX.—The Solar Spectrum in 1877–1878, with some practical idea of its probable temperature of Origination

1880 ◽  
Vol 29 (1) ◽  
pp. 285-342 ◽  
Author(s):  
Piazzi Smyth
Keyword(s):  
Great Britain ◽  
Royal Society ◽  
Solar Spectrum ◽  
The Sun ◽  
Atmospheric Phenomena

Although the Spectrum whose linear record is now presented to the Royal Society, Edinburgh, is unfortunately not so perfect as it might have been with better apparatus (but which I did not possess)—yet it represents the labour and expense connected with two voyages in 1877–1878 to Portugal; and many weeks work there in both years, with the sun in a more favourable position for observing really solar, and not telluric, or atmospheric, phenomena, than is ever, at any time, obtainable in Great Britain.

scholarly journals I. Researches on the spectra of meteorites. A report to the Solar Physics Committee. Communicated to the Royal Society at the request of the committee

1888 ◽  
Vol 43 (258-265) ◽  
pp. 117-156 ◽  
Keyword(s):  
Royal Society ◽  
Solar Physics ◽  
Solar Spectrum ◽  
The Sun ◽  
Metallic Elements ◽  
Chemical Constitution

Some years ago I commenced a research on the spectra of carbon in connexion with certain lines I had detected in my early photographs of the solar spectrum. I have been going on with this work at intervals ever since, and certain conclusions to which it leads, emphasising the vast difference between the chemical constitution of the sun and of some stars, recently suggested the desirability of obtaining observations of the spectra of meteorites and of the metallic elements at as low a temperature as possible. I have latterly, therefore, been engaged on the last-named inquiries. The work already done, read in conjunction with that on carbon, seems to afford evidence which amounts to demonstration on several important points.

scholarly journals V. Researches in spectrum-analysis in connexion with the spectrum of the sun

1874 ◽  
Vol 22 (148-155) ◽  
pp. 391-391
Keyword(s):  
Spectrum Analysis ◽  
Wave Length ◽  
Solar Spectrum ◽  
The Other ◽  
Photographic Method ◽  
The Sun ◽  
The Third

Maps of the spectra of calcium, barium, and strontium have been constructed from photographs taken by the method described in a former communication (the third of this series). The maps comprise the portion of the spectrum extending from wave-length 3900 to wave-length 4500, and are laid before the Society as a specimen of the results obtainable by the photographic method, in the hope of securing the cooperation of other observers. The method of mapping is described in detail, and tables of wave-lengths accompany the maps. The wave-lengths assigned to the new lines must be considered only as approximations to the truth. Many of the coincidences between lines in distinct spectra recorded by former observers bave been shown, by the photographic method, to be caused by the presence of one substance as an impurity in the other; but a certain number of coincidences still remain undetermined. The question of the reversal of the new lines in the solar spectrum is reserved till better pho­tographs can be obtained.

scholarly journals Analog Video Magnetograms in Real Time

1971 ◽  
Vol 43 ◽  
pp. 76-83 ◽  
Author(s):  
R. C. Smithson ◽  
R. B. Leighton
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Solar Magnetic Field ◽  
Solar Spectrum ◽  
Zeeman Splitting ◽  
The Other ◽  
Line Of Sight ◽  
Zero Field ◽  
The Sun ◽  
Solar Magnetic Fields

For many years solar magnetic fields have been measured by a variety of techniques, all of which exploit the Zeeman splitting of lines in the solar spectrum. One of these techniques (Leighton, 1959) involves a photographic subtraction of two monochromatic images to produce a picture of the Sun in which the line-of-sight component of the solar magnetic field appears as various shades of gray. In a magnetogram made by this method, zero field strength appears as neutral gray, while magnetic fields of one polarity or the other appear as lighter or darker areas, respectively. Figure 1 shows such a magnetogram.

scholarly journals I. Note on the spectrum of carbon

1880 ◽  
Vol 30 (200-205) ◽  
pp. 335-343 ◽  
Keyword(s):  
Solar Atmosphere ◽  
Royal Society ◽  
Solar Spectrum ◽  
Ultra Violet ◽  
The Other ◽  
Visible Part

In the year 1878 I communicated to the Royal Society a paper in which the conclusion was drawn that the vapour of carbon was present in the solar atmosphere. This conclusion was founded upon the reversal in the solar spectrum of a set of flutings in the ultra-violet. The conclusion that these flutings were due to the vapour of carbon, and not to any compound of carbon, was founded upon experiments similar to those employed in the researches of Attfield and Watts, who showed that the other almost exactly similar sets of flutings in the visible part of the spectrum were seen when several different compounds of carbon were exposed to the action of heat and electricity. In my photographs the ultraviolet flutings appeared under conditions in which carbon was the only constant, and it seemed therefore reasonable to assume that the flutings were due to carbon itself, and not to any compound of carbon.

scholarly journals Active bodies in the near-Earth region: The tenuous boundary between comets and asteroids

2015 ◽  
Vol 10 (S318) ◽  
pp. 142-143
Author(s):  
Julio A. Fernández ◽  
Andrea Sosa
Keyword(s):  
Dynamical Evolution ◽  
The Other ◽  
General Definition ◽  
The Sun ◽  
Main Belt ◽  
Close Encounters ◽  
The Earth ◽  
Bare Nucleus ◽  
Short Period ◽  
Near Earth Asteroids

AbstractWe analyze the dynamics and activity observed in bodies approaching the Earth (perihelion distancesq< 1.3 au) in short-period orbits (P< 20 yr), which essentially are near-Earth Jupiter Family Comets (NEJFCs) and near-Earth asteroids (NEAs). In the general definition, comets are “active”, i.e. they show some coma, while asteroids are “inactive”, i.e. they only show a bare nucleus. Besides their activity, NEJFCs are distinguished from NEAs by their dynamical evolution: NEJFCs move on unstable orbits subject to frequent close encounters with Jupiter, whereas NEA orbits are much more stable and tend to avoid close encounters with Jupiter. However, some JFCs are found to move on stable, asteroidal-type orbits, so the question arises if these objects are asteroids that have become active, perhaps upon approach to the Sun. In this sense they may be regarded as the counterparts of the main-belt comets (Hsieh & Jewitt 2006). On the other hand, some seemingly inert NEAs move on unstable, comet-type orbits, so the question about what is a comet and what is an asteroid has become increasingly complex.

Introductory remarks

1978 ◽  
Vol 284 (999) ◽  
pp. 1-2
Keyword(s):  
Great Barrier Reef ◽  
Royal Society ◽  
Accurate Determination ◽  
The Sun ◽  
Barrier Reef ◽  
The South ◽  
The Face ◽  
The Universe ◽  
Do So

What we are here to discuss concerns the Great Barrier Reef of Australia. It is very fitting that we should do so in this place, because the Royal Society was intimately concerned with events that led to its discovery in 1770. We go back to 1716, to a communication printed in Latin in the Philosophical Transactions by Edmond Halley, then Savilean Professor of Geometry at Oxford and Secretary of this Society. There, and for no less an objective than the more accurate determination of the dimensions of the Universe, he drew attention to the unique opportunities to that end to be presented by observing the transits of Venus across the face of the Sun due on 6 June 1761 and 3 June 1769. In the event international observations in the former year were largely fruitless, giving added reason for adequate observations in 1769. One of the conclusions of the specially appointed Transit Committee of the Society was that one site for observation should be in the South Seas.

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