Astronomical observatory

“ The only instrument which, as I think, may possibly be called for by the demands of the astronomer or the astronomical public, is a telescope of the largest size, for the observation of faint nebulae and minute double stars. Whether the addition of such an instrument to our apparatus would be an advantage, is, in my opinion, not free from doubt. The line of conduct for the Observatory is sufficiently well traced; there can be no doubt that our primary objects ought to be the accurate determination of places of the fundamental Stars, the Sun, the Planets, and, above all, the Moon. ”

“ In 1870, an observing-room for the transit-circle was added, forming an extension of the west wing. A tower and dome, to accommodate the superb new equatorial telescope recently completed, was finished in October. The equipment of the observatory in astronomical, magnetic, and meteorological instruments is now in a fair way to become worthy of the institution and the country it represents, and the library is increasing rapidly in the number of volumes and their scientific value. ”

“ When the progress of terrestrial magnetism and meteorology began to make regular observations necessary, the duty of taking these was often thrown on astronomical observatories, although in some cases separate institutions were created for the purpose. In this article the astronomical observatories will be chiefly considered.
Up to about 300 B.C. it can scarcely be said that an observatory existed anywhere, as the crude observations of the heavens then taken were only made by individuals and at intervals, employing the simplest possible apparatus. ”

“ A new observatory has been erected to supplement the uses of the old one, which was distinguished as being the first observatory for astronomical purposes erected in this country. The new one has mounted in it a meridian circle of the latest and best construction. Other instruments in both observatories in the hands of one so eminent as Professor Safford, furnish unusual means for the prosecution of astronomical studies. Clark Hall, a fine new building, contains the Wilder Mineralogical Cabinet and the [Pg 501] college archives. ”

“ The second remark is, that when persons well acquainted with the general facts of Astronomy are introduced into an Observatory, they are, for the most part, utterly unable to understand anything which they see; they are impressed perhaps with the apparent complexity of subsidiary parts of the Astronomical instruments, and they imagine that the fundamental principles of their construction are complicated, and too obscure for the understanding of ordinary men ”

“ I fear that I may in this way have strengthened an erroneous impression that the seat of important astronomical work is necessarily connected with an observatory. It must be admitted that an institution which has a local habitation and a magnificent building commands public attention so strongly that valuable work done elsewhere may be overlooked. A very important part of astronomical work is done away from telescopes and meridian circles and requires nothing but a good library for its prosecution. ”

“ It should be fixed at such a distance that the mark may be distinctly seen without altering the focus of the telescope when adjusted to the sun or stars, which, in most cases, will require to be at least half a mile from the place of observation, and more if it can be obtained.
Observatories may be distinguished into public and private. A private observatory may be comprehended in a comparatively small building, or in the wing of a building of ordinary dimensions for a family, provided the situation is adapted to it. ”

“ The building is by far the largest on the ground, but in little accord with the popular idea of an astronomer as perpetually looking through a telescope, carries but a single dome; its best rooms being set apart as 'computing rooms,' for the use of those members of the staff who are employed in the calculations and other clerical work, which form, after all, much the greater portion of the Observatory routine.
An observer with the transit instrument, for instance, will take only three or four minutes to make a complete determination of the place of a single star. ”

“ Even the Lick Observatory, which was built at the summit of Mount Wilson, 5885 feet high, at tremendous expense, cannot satisfy the astronomers. An observatory that would reach about twice that height, such as the one built by the scientist in this story, would be more likely to hit the mark. Certainly, the views obtained of the Moon, and even of Mars, through our present apparently gigantic telescopes, undoubtedly call for a higher observatory, fitted with a more enormous telescope, which will some day be established. ”

“ He must constantly ask himself, while using his instruments, "If I do this or that, what will happen, and why?" Now, it is presumably to forward this branch of Astronomy—Spherical Astronomy—that the college observatory was founded, and, if it does this in the right way, it is of great value. To do this properly, requires but a small outlay. A small equatorial of, say, four inches aperture, with circles divided to one minute, will serve to exhibit every thing of interest to the general observer, and will give a student much more opportunity for work than he can possibly find time to improve. ”

“ The Equatorial, which is the largest telescope in the Observatory, is mounted in the revolving dome which rises above the main building. It has a fourteen-feet refractor, and an object-glass nine inches in diameter. Its movements are most ingenious, being regulated by machinery and clock-work. Its powers are so great, that it renders stars visible at midday, and, if directed at a given star in the morning, its machinery will work so accurately, that it will follow with perfect exactness the path of the star, which will be visible through it as long as the star is above the horizon. ”

“ The telescope is driven by a most efficient clock, whose motive power is a heavy weight. The rate of the weight in falling is regulated by an ingenious governor, which brings its speed very nearly indeed to that of the star, and any little irregularities in its motion are corrected by the following device. A seconds pendulum is mounted in a glass case on the wall of the Observatory, and a needle at the lower end of the pendulum passes at each swing through a globule of mercury. ”

“ These giant telescopes, however, require an enormous object-glass or mirror, for the points of light are so spread out in making the large image that it is very faint unless an enormous number of rays are collected. Lord Rosse's telescope has a reflecting mirror measuring six feet across, and a man can walk upright in the telescope tube. The most powerful telescope yet made is that at the Lick Observatory, on Mount Hamilton, in California. It is fifty-six and a half feet long, the object-lens measures thirty-six inches across. ”

“ The upper deck was the main living quarters. There were several small rooms on each side of the corridor down the center; at the extreme nose was the control room, and at the extreme stern was the observatory. The observatory was equipped with a small but exceedingly powerful telectroscope, developed from those the Nigrans had left on one of the deserted planets Sol had captured in return for the loss of Pluto to the Black Star. The arc commanded by the instrument was not great, but it was easy to turn the ship about, and most of their observations could be made without trouble. ”

“ But the fact is when one is dealing with a fine instrument like Fig. 168 of as much as 5 inches aperture, the question of a permanent housing (call it observatory if you like) at once comes up and will not down.
It is of course always more convenient to have the telescope permanently in place and ready for action. Some observers feel that working conditions are better with the telescope in the open, but most prefer a shelter from the wind, even if but partial, and the protection of a covering, however slight, in severe weather. ”

“ Thus there is a telescope at Lord Rosse's Observatory, at Parsonstown in Ireland, which is the finest yet constructed. Its highest magnifying power is 6,000, therefore every object we look at with it is brought within the 6,000th of its distance from us. Looking at the moon, for instance, we know that our satellite is distant some 240,000 miles from us; we have, therefore, only to divide that number by 6,000 to find that by means of this wonderful instrument the moon is brought within 40 miles of the earth. ”

“ In 1879 a work of magnitude was begun—the photometric observation of all stars down to those of the sixth magnitude visible in this latitude. For greater facility, and particularly to avoid loss of time in identifying stars of small magnitude, it was decided to make a new departure in method and in construction of an instrument. The new instrument was called the meridian photometer, and stars were observed by it only when near the meridian. The position of any star being well known, the time of its appearance in the field of the telescope could be foreseen. ”

“ The next step beyond the eyepiece fixed in general position is so to locate it that the observer can be thoroughly protected without including the optical parts of the telescope in such wise as to injure their performance.
One cannot successfully observe through an open window on account of the air currents due to temperature differences, and in an observatory dome, unheated as it is, must wait after the shutter is opened until the temperature is fairly steadied. ”

“ The magnitude of this undertaking, as a whole, surpassed anything ever attempted in any other country.
In his report, reviewing the year 1848, the director says; “Some experiments made with the daguerreotype and talbotype processes for obtaining impressions of the sun’s image formed by the telescope have not been attended with complete success; however, we do not despair of ultimate success.” ”

“ By means of these levers, too, a rack and windlass, the observatory is brought to any degree of approximation to the pillars that the altitude of an observation may require; and although, when at its nearest station it cannot command an observation with the great lens within about fifteen degrees of the meridian, it is supplied with an excellent telescope of vast power, constructed by the elder Herschel, by which every high degree can be surveyed. ”

“ There is no enterprising head of an observatory but must feel cramped in his designs if he can command no more than 14 or 15 inches of aperture, and he aspires to greater instrumental capacity, not merely with a view to the chances of discovery, but for the steady prosecution of some legitimate line of inquiry. Thus projects of telescope-building on a large scale are rife, and some obtain realisation year by year. Sir Howard Grubb finished in 1893 a 28-inch achromatic for the Royal Observatory, Greenwich ”

“ His observatory was then a small, round building, and in it was a small telescope; he had drawn a map of a group of stars, one of which he supposed was not a star, but the planet. He set the telescope to this group, and asking his son to count the seconds, he allowed the stars to pass by the motion of the earth across the field. If they kept the relative distance of the night before, they were all stars; if any one had approached or receded from the others, it was a planet ”

“ An early application of photography in this investigation was in the direction of determining the color of stars, measuring their brightness by an independent method, picturing their spectra, exhibiting the effect of atmospheric absorption of light in a series of plates covering the period of a year, and ascertaining by images of stars trailed upon the plate, the clearness and steadiness of the atmosphere.
In 1887 the Boyden fund being available, the first step was taken in the important enterprise of giving a continental expansion to the work of the observatory. ”

“ Where this instrument is possessed, and in cases where no great degree of accuracy is required, the equatorial may be made to serve the general purposes of a transit instrument.
A private observatory might be constructed in any house which has a commanding view of the heavens, provided there is an apartment in it, in which windows may be placed, or openings cut out fronting the north, the south, the east and the west. ”

“ The details of observatory-work are not, properly speaking, scientific. They involve, no doubt, the continuous application of scientific principles, but no such processes as are likely to lead to discoveries in science. The ordinary notion, for instance, that the large telescopes of our national observatories are employed in advancing our knowledge of astronomy, is altogether erroneous, as any one will perceive who examines the records of the work done in those observatories. ”

“ Agreeably to the announcement of the annual report of Harvard College Observatory for 1877, as to photometry, a beginning was made by constructing a photometer suitable to be attached to the great telescope. Other photometers have been devised at different times for use independently. One of the earliest was applied during the year beginning Oct. 12, 1877, in measuring the light of all known satellites excepting the two inner ones of Uranus, which are too faint to be discerned, even by the great telescope. ”