XXII NOTES BY THE EDITOR 



ing its apex to that luminary, thus serving to illustrate, iii another aspect, 

 the sublime simplicity of. nature's laAvs. 



The Smithsonian Institution has published, for the use of those who 

 take part in the system of meteorological observations, a series of minute 

 directions, prepared by Prof. Guyot. It occupies forty octavo pages, with 

 wood-cut representations of the instruments, and two lithographic engrav- 

 ings, to illustrate the different forms of clouds, and to facilitate their nota- 

 tions in the journals, in accordance with the nomenclature adopted by 

 meteorologists. A set of tables has also been furnished for correcting the 

 barometrical observations, on account of variations of temperature. A series 

 of experiments have also been made, in the laboratory of the Institution, 

 for the purpose of constructing, from direct observation, a scale of boiling 

 temperatures, corresponding to different degrees of rarefaction of the air. 

 With a thermometer, each degree of which occupies one inch in length of 

 the scale, the variations of the boiling point, corresponding to a slight 

 change in altitude, are found to be more perceptible than those in the 

 length of the barometrical column. A valuable collection of returns, rela- 

 tive to the Aurora, has also been made to the Smithsonian Institution. 

 These are to be placed in the hands of Capt. Lefroy, of the Toronto Observ- 

 atory, and incorporated with observations of a similar kind collected in 

 British North America. An account in full, of the series, will be hereafter 

 published by the Institution. 



The progress of Astronomy, during the past year, has been very great. 

 The Earl of Rosse has been much engaged in experiments on the best meth- 

 ods of supporting and using his large mirrors. The construction adopted 

 some time since is still retained ; namely, a system of levers, distribut- 

 ing their pressures uniformly over eighty-one points, each pressure being 

 transmitted through a small ball, which permits to the mirror perfect 

 freedom of slipping in its own plane, so as to take propqr beai-ing in the 

 chain or hoop which supports it edgeways. To Lord Rosse's critical eye, 

 the effect even of this mounting, though greatly superior to that of any 

 preceding, is not quite perfect. By the aid of his large reflector, some new 

 instances of spirally-arranged nebulas have been discovered ; some strik- 

 ing examples of dark holes in bright matter, dark clefts in bright rays, 

 and the resolution of nebulous matter into stars, have also been made 

 known. 



The determination of the parallax of the star a Centauri is a subject of 

 great interest. Observations made by Prof. Henderson give to this star a 

 parallax of 0".9187. The parallax separately deduced by Mr. Mclear, the 

 Astronomer Royal at the Cape of Good Hope, is // .9128, showing an accord- 

 ance greater than the most sanguine could have anticipated. It has been 

 recently announced, that a continuation of the observations at the Cape 

 fully confirm the results first obtained, namely, that the parallax of a Ceil- 



