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THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



[July, 



motive power \a meteorology, whose mode of action, and the mechanism 

 through which it acts, have yet to be inquired into. Mr. Daniell's claims to 

 scientific distinction were, however, not confined to tliis branch. In his 

 hands, the voltaic pile became an infinitely more powerful and manageable 

 instrument, than bad ever before been thought possible ; and his improve- 

 ments in its construction (the effect not of accident, bui of patient and per- 

 severing experimental inquiry), have in effect clianged the face of Electro- 

 chemistry. Nor did he coufiiie himself to these improvements. He applied 

 them: and among the last and most interesting inquiries of his life, are a 

 series of electro-chemical researches which may rank with the best things yet 

 produced in that line. 



The immediate importance of these subjects to one material part of our 

 business at this meeting, has caused me to dwell more at length than per- 

 haps I otherwise should on them. I would gladly use what time may remain 

 without exciting your impatience, in taking a view of some features in the 

 present state and future prospects of that branch of science to which my own 

 attention has been chiefly directed, as well as to some points in the philoso- 

 phy of science generally, in which it appears to me that a disposition is be- 

 coming prevalent towards lines of speculation, calculated rather to bewilder 

 than enlighten, and, at all events, to deprive the pursuit of science of that 

 which, to a rightly constituted mind, mvist ever be one of its highest and most 

 attractive sources of interest, by reducing it to a mere assemblage of marrow- 

 less and meaningless facts and laws. 



Lord Rosse's Telescope. 



The last year must ever be considered an epoch in Astronomy, from its 

 having witnessed the successful completion of the Earl of Rosse's six-feet 

 reflector — an achievement of such magnitude, both in itself as a means of 

 discovery, and in respect of the difliculties to be surmounted in its construc- 

 tion, (difficulties which perhaps few persons here present are better able 

 from experience to appreciate than myself), that I want words to express my 

 admiration of it. I have not myself been so fortunate as to have witnessed 

 its performance, but from what its nolile constructor has himself informed 

 me of its effects on one particular nebula, with whose appearance in power- 

 ful telescopes I am familiar, I am prepared for any statement which may be 

 made of its optical capacity. What may be the effect of so enormous a 

 power in adding to our knowledge of our own immediate neighbours in the 

 universe, it is of course impossible to conjecture ; but for my own part I 

 cannot help contemplating, as one of the grand fields open for discovery with 

 such an instrument, those marvellous and mysterious bodies or systems of 

 bodies, the Nebula;. By far the major part, probably, at least, nine-tenths 

 of the nebulous contents of the heavens consist of nebula; of spherical or 

 elliptical forms presenting every variety of elongation and central condensa- 

 tion. Of these a great number have been resolved into distinct stars, and a 

 vast multitude more have been found to present that mottled appearance 

 •which renders it almost a matter of certainty that an increase of optical 

 power would show them to be similarly composed. A not unnatural or un- 

 fair induction would therefore seem to be, that those which resist such reso- 

 lution do so only in consequence of the smallness and closeness of the stars 

 of which they consist ; that, in short, they are only optically and not physi- 

 cally nebulous. There is, however, one circumstance which deserves especial 

 remark, and which, now that my own observation has extended to thenebulEe 

 of both hemispheres, I feel able to announce with confidence as a general 

 law, viz. that the character of easy resolvability into separate and distinct 

 stars, is almost entirely confined to nebula; deviating ijut little from the 

 spherical form ; while, on the other band, every elliptic nebula:, even large 

 and bright ones, offer much greater difficulty in this respect. The cause of 

 this difference must, of course, be conjectural, but, I believe, it is not possible 

 for any one to review seriatim the nebulous contents of the heavens without 

 being satisfied of its reality as a physical character. Passihly the limits of 

 the conditions of dynamical stability in a spherical cluster may be compatible 

 with less numerous and comparatively larger individual constituents than in 

 an elliptic one. Be that as it may, though there is no doubt a great number 

 of elliptic nebula; in which stars have not yet been noticed, yet there are so 

 many in which they have, and the gradation is so insensible, from the most 

 perfectly spherical to the most elongated elliptic form, that the force of the 

 general induction is hardly weakened by this peculiarity ; and for my own 

 part I should have litfle hesitation in admitting all nebula; of this class to be, 

 in fact, congeries of stars. And this seems to have been my father's opinion 

 of their constitution, with the exception of certain very peculiar looking ob- 

 jects, respecting whose nature all opinion must for the present be suspended. 

 Now, among all the wonders which the heavens present to our contempla- 

 tion, there is none more astonishing than such close compact families or 

 communities of stars, forming systems either insulated from all others, or in 

 binary connexion, as double clusters whose confines intermix, and consisting 

 of individual stars nearly equal in apparent magnitude, and crowded together 

 in such multitudes as to defy all attempts to count or even to estimate their 

 numbers. What are these mysterious families.' Under what dynamical 

 conditions do they subsist? Is it conceivable that they can exist at all, and 

 endure under the Newtonian law of gravitation without perpetual collisions ? 

 And, if so, what a problem of unimaginable complexity is presented by such 

 a system if we should attempt to dive into its perturbations and its condi- 

 tions of stability by the feeble aid of our analysis. The existence of a lumi- 

 nous matter, not congregated into massive bodies in the nature of stars, but 

 disserainatrd through vast regions of space in a vaporous or cloud-like state, 

 undergoing, or awaiting the slow process of aggregation into masses by the 



power of gravitation, was originally suggested to the late Sir \X. Herschel in 

 his reviews of the nehula;, by those extraordinary objects wliich his researches 

 disclosed, which exhibit no regularity of outline, no systematic gradation of 

 brightness, but of which the wisps and curls of a cirrhus cloud afford a not 

 inapt description. The wildest imagination can conceive nothing more capri- 

 cious than their forms, which in many instances seem totally devoid of plan 

 as much so as real clouds, — in others offer traces of a regularity hardly less 

 uncouth and characteristic, and which in some cases seems to indicate a 

 cellular, in others a sheeted structure, complicated in folds as if agitated by 

 internal winds. 



Should the powers of an instrument such as Lord Rosse's succeed in re- 

 solving these also into stars, and, moreover, in demonstrating the starry na- 

 ture of the regular elliptic nebulae, which have hitherto resisted such decom- 

 position, the idea of a nebulous matter, in the nature of a shining fluid, or 

 condensible gas, must, of course, cease to rest on any support derived from 

 actual observation in the sidereal heavens, what countenance it may still re- 

 ceive in the minds of cosmogonists from the tails and atmospheres of comets, 

 and the zodiacal light in our own system. But though all idea of its being 

 ever given to mortal eye, to view aught that can be regarded as an outstand- 

 ing portion of prima;val chaos, be dissipated, it will by no means have been 

 even then demonstrated that among those stars, so confusedly scattered, no 

 aggregating powers are in action, tending to draw them into groups and in- 

 sulate them from neighbouring groups ; and, speaking from my own impres- 

 sions, I should say that, in the structure of the Magellanic Clouds, it is 

 really difficult not to believe we see distinct evidences of the exercise of such 

 a power. The part of my father's general views of the construction of the 

 heavens, therefore, being entirely distinct from what has of late been called 

 " the nebulous hypothesis," v\'ill still subsist as a matter of rational and philo- 

 sophical speculation, — and perhaps all the better for being separated from 

 the other. 



The Nebtdous Ht/pothesis. 



Much has been said of late of the Nebulous Hypothesis, as a mode of re- 

 presenting the origin of our own planetary system. An idea of Laplace, of 

 whicli it is impossible to deny the ingenuity, of the successive abandonment 

 of planetary rings, collecting themselves into planets by a revolving mass 

 gradually shrinking in dimension by the loss of heat, and finally concentrat- 

 ing itself into a sun, has been insisted on with some pertinacity, and sup- 

 posed to receive almost demonstrative support from considerations to which 

 I shall presently refer. I am by no means disposed to quarrel with the ne- 

 bulous hypothesis even in this form, as a matter of pure speculation, and 

 without any reference to final causes ; but if it is to be regarded as a demon- 

 strative truth, or as receiving the smallest support from any observed nume- 

 rical relations which actually bold good among the elements of the planetary 

 orbits, I beg leave to demur. Assuredly, it receives no support from obser- 

 vation of the effects of sidereal aggregation, as exemplified in the formation 

 of globular and elliptic clusters, supposing them to have resulted from such 

 aggregation. For were this the cause, working itself out in thousands of in- 

 stances, it would have resulted, yiot in the formation of a single large central 

 body, surrounded by a few much smaller altendants, disposed in one plane 

 around it, — but in systems of infinitely greater complexity, consisting of mul- 

 titudes of nearly equal luminaries, grouped together in a solid elliptic or glo- 

 bular form. So far, then, as any conclusion from our observations of nebute 

 can go, the result of agglomerative tendencies jnai/, indeed, be the formation 

 of families of stars of a general and very striking character ; but we see no- 

 thing to lead us to presume its further result to be the surrounding of those 

 stars with planetary attendants. If, therefore, we go on to push its applica- 

 tion to that extent, we clearly theorize in advance of all inductive observa- 

 tion. 



But if we go still farther, as has been done in a philosophical work of 

 much mathematical pretension, which has lately come into a good deal of 

 notice in this country,* and attempt " to give a mathematical consistency" 

 to such a cosmogony by the *' indispensable criterion" of ** a numerical verifi- 

 cation," — and so exhibit, as " necessary consequences of such a mode of 

 formation," a series of numbers which observation has established independent 

 of any such hypothesis, as primordial elements of our system — if, in pursuit 

 of this idea, we find the author first computing the lime of rotation the sun 

 must have had about its axis so that a planet situate on its surface and form- 

 ing a part of it should not press on that surface, and should therefore be in 

 a state of indifference as to its adhesion or detachment — if we find him, in 

 this computation, throwing overboard as troublesome all those essential con- 

 siderations of the law of cooling, the change of spheroidical form, the internal 

 distribution of density, the probable non-circulation of the internal and ex- 

 ternal shells in the same periodic time, on which alone it is possible to exe- 

 cute such a calcidation correctly ; and avowedly, as a short cut to a result, 

 using as the basis of his calculation " the elementary Huyghenian theorems 

 for the evaluation of centripetal forces in combination with the law of gravi- 

 tation ;" — a combination which, I need not explain to those w!io have read 

 the first book of Newton, leads direct to Kepler's law ; — and if we find him 

 then gravely turning round upon us, and adducing the coincidence of the 

 resulting periods compared with the distances of the planets with this law of 

 Kepler, as beinr/ the numerical verification in question, — where, I would ask, 

 is there a student to be found who has graduated as a Senior Optime in this 

 University, who will not at once lay his finger on the fallacy of such an 



« W. Conite, Phil. Positive, ii. 3."ti. 



