42 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



erable increase in the number of stars has lately taken place, 

 and there are now visible 170, as compared with 134 visible 

 a year since. The boundary of the dark space within the 

 nebula has now six openings, but is gradually becoming less 

 distinct. Monthly Notices Hoy. Soc. Tasmania, 1872, p. 27. 



THE ORBIT OF A BRIGHT METEOR. 



Professor Galle, in the course of an investigation of the 

 path pursued by a bright meteor, on the 17th of June, 1873, 

 takes occasion to develop with great thoroughness the math- 

 ematical formulae appropriate to such studies, in the use of 

 which, in preference to any graphical construction, he seems 

 justified by the unusually large number of accurate observa- 

 tions of this meteor. A singular observation of the beginning 

 of the visible path of the meteor in question an observation 

 that was, in fact, of rare accuracy was made by Mr. Sage, 

 the principal of a high-school, who, happening to be looking 

 at the planet Mars, saw it, apparently, break in two, and the 

 next moment perceived that a meteor had come into view 

 directly between himself and Mars. For a short time the 

 meteor appeared to him without movement, and then slowly 

 passed to the westward. In Galle's computations, he de- 

 duces as the orbit of the meteor a hyperbola having the sun 

 in its focus, and scarcely appreciably inclined to the earth's 

 orbit. Astronomische Kachrichten , vol. lxxxiii., p. 320. 



THE FLATTENING OF THE PLANET MARS. 



Reverting to the proposition laid down by mathematicians, 

 that the flattening of a liquid planet revolving on its axis 

 must be contained within the limits \ and - of the ratio be- 

 tween the attraction of the planet and the centrifugal force, 

 and considering further that the planet Mars has a flattening 

 quite in excess of f, Amigues has proposed to inquire into 

 the question What would be its flattening under the sup- 

 position that this planet has been formed, as we may say, by 

 two successive operations ? At first, according to him, a 

 solid nucleus must have resulted from the cooling of a pre- 

 vious liquid mass; and, at the second step, by some means 

 not suggested by him, we must imagine a mass of cosmical 

 matter passing in the neighborhood of the planet to have 

 been attracted by it to itself permanently, and to have formed 



