264 Chronicles of Science. [-A^pi'ilj 



would give a period liaving some simple association of commen- 

 sm-ability with the period of Jupiter. It is well known that 

 any such association would result in disturbance, and Professor 

 Kirkwood argues that the particles which, on the nebular hypo- 

 thesis, would have occupied these vacant zones, must have been so 

 disturbed by Jupiter, as to adopt eccentric orbits, and so come into 

 collision with exterior or interior particles. Even if this did not 

 happen, the disturbance of their orbits would lead to a change of 

 period and so of mean distance. Either result serves to account 

 for the gaps in the asteroidal zone. He considers that very 

 strong evidence is afforded by these coincidences (which certainly 

 cannot be looked upon as accidental) in favour of the nebular 

 hypothesis. He goes on to examine the Saturnian rings, which he 

 remarks have been quoted in Proctor's Saturn as furnishing strong 

 evidence of the nebular hypothesis of Laplace. He shows that the 

 great division between the rings corresponds exactly with that 

 portion of the width of the system where the particles would move 

 in periods commensurate with those of the four inner satellites. 

 The coincidence is certainly most remarkable. The whole paper is 

 well worthy of careful study, being founded on well-estabhshed 

 mathematical principles, and serving to bring together and account 

 for a number of remarkable relations in the solar system. 



Mr. Stone supphes a paper upon Aboul Hhassan's catalogue of 

 240 stars, which he shows to have been derived from Ptolemy's 

 catalogue, and not (as Delambre had supposed) from Arzachel's. 

 It is known that Ptolemy derived his catalogue from that of 

 Hipparchus by applying an erroneous correction for precession. 

 Mr. Stone shows how this fact may have led to the Arabian notion 

 that the processional motion is oscillatory. " If this view be 

 correct," he says, " Ptolemy's want of candour respecting the 

 nature of his catalogue is thus found to be throwing astronomy into 

 complexities more than 1100 years after his death." 



4. BOTANY, VEGETABLE ]\rOBPHOLOGY AND 

 PHYSIOLOGY, AND ECONOMIC BOTANY. 



Sterility of Hermaphrodite Flowers. — Mr. Thomas Meeham has 

 observed that the flowers of Epigoea repens are practically dioecious 

 — since the hermaphrodite flowers are sterile. He is led to specu- 

 late upon this observation, as to whether the dicecious character 

 may not be a result of subsequent changes in the development of 

 a once monoecious form, and suggests that all plants would be pri- 

 marily monoecious but that there is a kind of exhaustion of the 



