322 ANNUAL OF SCIENTIFIC DISCOVERY. 



I 



rocess of development is frequently conspicuous, even when no regu- 

 ar period can be established ; this was made very evident in the succes- 

 sion of envelopes raised from the nucleus of Donati's comet, as de- 

 scribed by several observers, and more especially by Bond ; it was 

 again manifest in the marvellous alternations of brightness exhibited by 

 Comet III. 1860; and reappeared strikingly in the aspect of the brill- 

 iant comet of the fall of 1862. As remote as most of these phenom- 

 ena are from all our terrestrial analogies, a still wider deviation is to 

 be found in the tendency of cometary matter to repulsion, expansion, 

 and ultimate dispersion. In the formation of the jets and envelopes, 

 in the emission of the tail, in its irreclaimable projection to uncontrolled 

 distances, and in the actual disruption of the main mass, to which 

 there seemed a slight tendency in " the Donati," more in III. 1860, 

 still more in I. 1860, and of which Biela's comet, in 1846, appeared to. 

 offer a perfect example, we see indications of a process very foreign 

 to our own experience, but remarkably characteristic of cometary mat- 

 ter. This brief and imperfect enumeration of some of the points, which 

 we may look upon as " vantage ground " in such inquiries, may be use- 

 ful in assisting amateurs to prepare for the next opportunity of further 

 research, which, though it may be expected to confirm some of these 

 deductions, may probably at the same time surprise us with unforeseen 

 anomalies ; for it is an interesting fact that as th*ere is a broad family 

 likeness, so to speak, among the whole class, so each individual (of any 

 considerable magnitude) is apt to be distinguished by such peculiarities 

 as imply most curious variations in composition ; even in the same indi- 

 vidual, diversities of color, or want of symmetry in form, give rise to 

 the idea of a combination of various materials, all, to us, equally un- 

 known. What can more strongly impress upon our minds the extent 

 of our own ignorance, or the vastness and complexity of the work of 

 the great Creator ! Intellectual Inquirer. 



PROGRESS IN OBSERVING SOLAR PHENOMENA. 



At the recent meeting of the British Association, Prof Phillips de- 

 scribed a most ingenious invention of the English optician, Cooke, by 

 which he has succeeded in separating the heat of the solar rays from 

 the luminous portion before their arrival at the focus. The eye-piece 

 constructed by him has a prism of 45 and a right angle, with one of 

 its faces presented to receive the light after leaving the object-glass ; 

 the luminous rays are then received on the back of the prism" at a 

 larger angle than that of total reflection, so that fully ninety-five per 

 cent, of them are reflected and pass on to the eye-piece ; but the heat- 

 ing rays, from their having a smaller refractive index, are for the most 

 part permitted to pass out at the back of the prism and are not reflect- 

 ed to the eye-piece, so that at least ninety-five per cent, of them are 

 thus got rid of. By this simple contrivance the utmost comfort is se- 

 cured to the observer engaged in examining the sun. 



Dr. Lee, in remarking upon the increased facility which the above 

 and other inventions have afforded to astronomers for investigating 

 solar phenomena and their effects, said, " That their origin as yet re- 

 mains unfathomable, like the question, Whence .come the perpetual 

 beams of light and heat of the orb itself? Yet these particulars, the 

 theme of endless plausible cogitations and ingenious suggestions with- 



