

METEOKS AND AEROLITES. 277 



and to seek conclusions as to other matter than that which 

 surrounds us on the surface of the earth. We may justly 

 apply to the science of our own day a sentence of older date 

 and other application Si computes annos, exiguum tern- 

 pus ; si vices rerum, cevum putes* 



We have yet to notice briefly other physical characters 

 belonging to these singular bodies. An important fact is 

 their general fragmentary aspect, as if struck off or detached 



* Since this article was first published, the opinion here expressed has been 

 unexpectedly justified by the discoveries made through the method of the Spec- 

 trum Analysis. This new and wonderful instrument of research, of which we 

 have elsewhere spoken (page 30), in disclosing to us the existence of six known 

 metals in the luminous atmosphere surrounding the Sun, has confirmed the in- 

 ference drawn from the composition of aerolites, and furnished to physical science 

 a mode of material access to the worlds in space around us. The same method 

 of enquiry (certain, as far as we can yet see, in the evidence it affords) is sure 

 to augment hereafter the knowledge thus obtained. The dark lines of the 

 spectrum left for interpretation are still exceeding numerous, and form in 

 themselves a large mine for research. To the two new metals, Caesium and 

 Rubidium, first discovered by Bunsen through their spectrum lines, a third 

 (Thallium) has recently been added by the labours of Mr. Crookes ; nor is there 

 any obvious limit to the extent to which such discovery may be carried in future. 



This new path, however, though a very seductive one, needs much patience 

 as well as zeal to follow it aright. Many perplexing questions occur in the 

 outset, as to the conditions of temperature, vaporous state, chemical action, &c., 

 which modify or change the refrangibilities of different elements (whether 

 metallic vapours or simple elements) expressed by these spectrum lines. The 

 experiments of Professor Pliicker (see Proceedings of Royal Society, 1859), 

 with an apparatus admirably contrived to concentrate the heat of the electric 

 current, show the wonderful influence of heat, simply considered, in determin- 

 ing all these results, and the importance of employing it in its simplest as well 

 as most energetic form. The spectrum lines he obtained for hydrogen, sul- 

 phur, &c., attest the value of this method of experiment, which will doubtless 

 be carried into further use. 



Meanwhile, we may repeat the main fact, that we have evidence of several 

 kinds of matter, familiarly known on our own globe, existing also in that greater 

 globe, which forms the centre of our system ; Iron especially conspicuous 

 among these substances. It is needless to speak of the many inferences which 

 hang, almost inseparably, on this single fact. It will at once be seen how much 

 they strengthen our views as to the origins of the remarkable bodies which form 

 the subject of this article ; while in more remote speculation, they promise 

 some future knowledge of the matter of other planets, and even of certain fixed 

 stars, which exhibit analogous lines in their spectra, permanently the same for 

 each. 



