396 Proceedings of Learned Societies. 



east, but would go forward and render the passage round the Cape 

 much more dangerous than it is. Capt. Toynbee recommended 

 outward-bound ships to delay crossing the fortieth parallel till the 

 longitude of 10° E. is reached, and stated that as the sea on the 

 Agulhas Bank is always several degrees colder than that to the 

 eastward of it, the thermometer is a good guide to tell a ship when 

 she is coming near the land. 



ROYAL INSTITUTION.— May 19. 



The Friday evening discourse was delivered by Mr. W. Huggins, 

 on the Chemical and Physical Constitution of the Stabs and 

 Nebulae. The heavenly bodies occupy a position of pre-eminence, 

 as they afford the only means of obtaining information as to objects 

 in the universe "external to the earth; but the experimentalist has 

 to cope with the difficulty that four out of the five senses fail him 

 in the investigation. Light is our only means of communication ; 

 but still the distances, magnitudes, and motions of many of these 

 bodies have been determined. As with sound, we can distinguish 

 not only the note, but the kind of material producing it, whether 

 wood, brass, or string ; so light gives indications of the substance 

 from which it emanates. Newton first decomposed light by a prism, 

 and showed that some rays are spread out more than others. 

 Wollaston and Frauenhofer discovered the dark lines crossing the 

 spectrum, and these lines reveal the constitution of the body ; but 

 this was written in cipher till 1859, when Kirchhoff announced the 

 mode of interpreting it. Spectra are of three orders. First, a 

 continuous coloured band, which we know must be produced by an 

 incandescent solid or liquid, but which gives no indication of the 

 nature of the luminous substance. Second, a spectrum, consisting of 

 a few bright lines, which is produced by a gas or vapour. Each 

 substance has a spectrum of its own, and that of an unknown body ; 

 being compared with the known elements, we recognize certain 

 similar groups of lines, and find what it is. The spectra of the 

 electric light and the magnesium were shown, to illustrate these 

 orders. The third kind is a coloured spectrum crossed with dark 

 lines, and these lines are produced by the absorbing effect of vapours 

 surrounding the incandescent body, each substance in the state of 

 vapour being opaque to the light produced by the same substance 

 when luminous. It is, therefore, obvious that when we find what dark 

 lines correspond with the light lines produced by luminous vapours, 

 we are sure those substances exist around or at the surface of the 

 light giving body. Kirchhoff explained on this principle the con- 

 stitution of the sun, and the lecturer had extended this mode of 

 observation to the moon, planets, fixed stars, and nebulaa. Our 

 resume of the researches of Mr. Huggins and Dr. Miller, contained 

 in the Intellectual Observer for January, renders it unnecessary 

 to repeat in detail these beautiful discoveries by which some of the 

 elements in Aldebaran, Betelgeux, Sirius, and about fifty other 

 stars, were determined. The lecturer dwelt upon the extraordinary 

 absence of hydrogen from a Orionis, and speculated on the condition 



