140 



REVELATIONS OF LORD ROSSE'S TELESCOPES IN THE SIDEREAL HEAVENS. 



[1854 



Tlio Earl of Kosse's Telescopi >, and llicir Kevelalious ill 

 the s dercal Heavens. 



,* 



r. r. s., s. l. & e., etc.* 

 ipterestins subjects, recently 



BY REV. W. SCORESBY, D. D. ; 



In a second lecture on these 

 delivered at Torquay, much and important consideration was 

 given to the inquiry, — What has the gigantic telescope done ? 



The lecturer having himself had the privilege of observing on 

 different visits, and for considerable periods, with both the instru- 

 ments, was enabled to reply, he hoped in a satisfactory manner, 

 to this inquiry. His opportunites of observing, he said, not- 

 withstanding interruptions from clouds and disturbed atmosphere, 

 had been somewhat numerous, and, not unfi equently, highly 

 instructive and delightful. Of these observations he had made 

 records of nearly 60, on the moon, planets, double stars, clusters, 

 and nebula?. He had been permitted also to have free access to, 

 and examination of, all the observatory records and drawings, so 

 that he was enabled on the best grounds, he believed, to say, that 

 there had been no disappointment in the performance of the 

 instruments ; and that the great instrument, in its peculiar quali- 

 ties of superiority, possesses a marvellous power in collecting 

 light and penetrating into regions of previously untouched space. 

 In what may be called the domestic regions of our planet — the 

 objects in the solar system — all that other instruments may 

 reveal is within its grasp or more, though by the prodigious flood 

 of light from the brighter planets, the eye is dazzled unless a 

 large portion is shut out. 



But in its application to the distant heavens and exploration of 

 the nebulous systems there, its peculiar powers have, with a 

 steady atmosphere, their highest developments and noblest tri- 

 umphs. In this department — that to which the instrument has 

 been particularly directed — every known object it touches, when 

 the air is favorable, is, as a general fact, exhibited under some 

 new aspect, It pierces into the indefinite or diffuse nebulous 

 forms shewn by other instruments in a general manner, and 

 either exhibits configurations altogether unimagined, or resolves 

 perhaps the nebulous patches of light into clusters of stars. 

 Guided in the general researches by the works of the talented 

 and laborious Herschels-^-to whom astronomy and science owe a 

 deep debt of gratitude — time has been economized, and the 

 interests of the results vastly enhanced. So that many objects 

 in which the fine instruments of other observers <eould discern 

 only some vague indefinite patch of light, have been brought out 

 in striking, definite, and marvellous configurations. 



Among these peculiar revelations ^ that of the spiral form — 

 the most striking and appreciable of all — which we may venture 

 to designate " The Rossean Configuration." Its discovery was 

 at once novel and splendid ; and in reference to the dynamical 

 principles on which these vast aggregations of remote suns are 

 whirled about within their respective systems and sustained 

 against interferences, promises to be of the greatest importance. 



One of the most splendid nebula? of this class — the great 

 spiral or whirlpool — has been figured in the Philosophical 

 Transactions for 1850. It may be considered as the grand type 

 and example of a class ; for near 40 more, with spiral character- 

 istics, have been observed, and about 20 of them carefully 

 figured. Dr. Scoresby had the pleasure of being present at the 

 discovery of this particular form in a nebula of the planetary 

 denomination, in which two portions following spiral forms were 

 detected. Its color was peculiar, — pale blue. He bad the 

 privilege, too, of being present on another interesting oecasion, 

 when the examination of the great nebula in Orion was first 

 seen to yield decisive tokens of resolution. 



• An abstract of a lecture dHiveted hi 'lorquny, November 15, 18-52. — 

 From Ihe Edinburgh New Pbilusophioal Journal for January, J853— Sill. 

 J.njr, 



Iii those departments of research, the examination of the con- 

 figurations of nebula;, and the resolution of nebulae into stars, 

 the six-feet speculum has had its grandest triumphs, and the 

 noble artificer and observer the highest rewards of his talents and 

 enterprise. Altogether, the quantity of work done, during a 

 period of about seven years,— including a winter when a noble 

 philanthropy for a starving population absorbed the keenest 

 interests, of science, — has been decidedly great, and the new 

 knowledge acquired, concerning the handiwork of the Great 

 Creator, amply satisfying of even sanguine anticipations. 



Dr. Scoresby found, in September last, that about 700 cata- 

 logued nebula? had been already examined, and transferred to the 

 ledger records fi'om the journals of the Obseivatory, ('comprising 

 only a selection from the general observations,) and the new neb- 

 ula, or nebulous knots, discovered merely incidentally, amounted 

 to 140 or more. The number of observations, involving separate 

 sets of the instru nent, recorded in the ledger, (exclusive of very 

 many hundreds, possibly thousands, on the moon and planets,) 

 amount to nearly 1700, involving several hundreds of determi- 

 nations of position and angular measurements with the micrometer 

 on the far distant stars. The carefully drawn configurations, 

 eliciting new characteristics, exceed 90, and the rough or less 

 finished sketches amount to above 200. Of the 700 catalogued 

 nebuke already examined, it should be observed, that in full one- 

 half or more, something new has been elicited. 



In speaking of the effects of the flood of light accumulated 

 by the six-feet speculum of the Earl of Rosse, Dr. Scoresby 

 remarked, that this peculiarity of the instrument (connected as it 

 is with due length of focus and admirable definition) enabled it 

 to reach distances in space far beyond the powers of any other 

 instrument. This was its peculiar province ; and in this, as to 

 existing instruments, tbere was not, nor, as he hoped to shew, 

 could there be, any competition. For comparing the space- 

 penetrating power of the six-feet speculum with one of two feet 

 . (which has rarely been exceeded) we find it three to one in favor 

 of the largest, with an accumulation of light in the ratio of 6 3 

 to 2 2 , or 9 to 1. On comparing the powers of this magnificent 

 instrument with those of a refractor of two feet aperture, the 

 largest hitherto attempted, we have a superiority — making a 

 due allowance for the loss of light by reflection from two mir- 

 rors, and assuming an equal degree of peifectness, figure, and 

 other optical requirements in the refractor, and no allowance for 

 absorption of light — in the ratio of about 4-5 to 1, as to light, 

 and as 2" 12 to 1, as to the capability of penetrating space, or 

 detectiug nebulous or sidereal objects at the extreme distance 

 of visibility. Hence, whilst the range of telescopic vision in a 

 refractor of two feet aperture would embrace a sphere in space 

 represented by a diameter of 2 ; the six-feet speculum (assuming 

 both instruments to be of equal optical perfection, magnifying 

 equally, and allowing fifty per cent, for loss of light for two 

 reflections in the one ■ case, and none ( ?) in the other) would 

 comprehend a sphere of about 4-24 diameter, — the outer shell 

 of which, 1-12 in thickness, being the province of the great 

 instrument alone. But let us reduce those proportions to sections 

 of equal spaces, that we may judge more accurately of the rela- 

 tive powers. Now, the solid contents of different spheres, we 

 know, are in the ratio of their diameters. Hence the compara- 

 tive spheres, penetrated by the two instruments referred to, should 

 be 4-24 3 to 2 3 ; that is, as 9-5 to 1. Deducting, then, from this 

 vast grasp of space the inner sphere, capable of being explored 

 by other instruments, we find that, out of nearly ten sections of 

 space reached by this telescope, there are neariy nine sections 

 which the six feet speculum may embrace as peculiarly its own ! 



What its revelations yet may prove, then, we can have no idea. 

 Several thousands of nebulae have been catalogued : the great 



