156 SCIENTIFIC NEWS. 



the eyes of observers, any errour which may arise from this 

 source will also be done away by this method. 

 General re- Hence it would appear, that, in order to obtain a correct 



quisites. difference of longitude of two places from correspondent 



eclipses of the satellites of Jupiter, the circumstances at 

 both places should be similar and favourable; and that the 

 telescopes should have equal powers, or that both im- 

 mersions and emersions should be observed, which indeed 

 ought always to be done, where time will admit : also, that, 

 the circumstances being favourable atone place and not so 

 at the other, a result very different from the truth will be 

 obtained. 



• : "~- ' 



SCIENTIFIC NEWS. 



Faikinson'sOr- J[ jt£ fi rst volume of Mr. Parkinson's Organic Remains 

 janic cmain . ^ & former World, which I have noticed in Vol. IX, p. 143, 

 has been some time before the public; and I have now the 

 satisfaction of announcing the second, which is no way in- 

 ferior to its predecessor. I trust it will be a subject of gra-» 

 tification rather than disappointment to my readers to find, 

 that its indefatigable author has not been able to close hi$ 

 labours on the fossil remains of the animal world with the 

 present volume, and that he cannot even pledge himself to 

 limit them to a third ; as he very judiciously means to ren- 

 der it as complete as possible, without admitting any super- 

 fluous matter. In his arrangement he nearly follows Wal- 

 lerius, who, after treating of vegetables, proceeds through 

 corals, worms, shells, insects, amphibia, fishes, birds, and 

 quadrupeds up to man. The present volume is confined 

 to zoophytes, many figures of which are given in twenty 

 plates, executed with much elegance, and the greater part 

 of them coloured after nature. 



To enter into any adequate detail of the whole, or notice 



all the most striking parts, would much exceed my limits; 



I shall at present confine myself therefore to the following 



observations on madrepores. 



Madrepores, Under the genus madrepore are placed all those corals, 



the 



