138 Linncean Society, Astronomical Society. 



tion of the apogee of the earth's orbit, the two hemispheres vvou Id 

 alternately be placed in climates of a very opposite nature, the one 

 approaching to a perpetual spring, the other to the extreme vicis- 

 situdes of a burning summer and a rigorous winter ; and that, du- 

 ring periods sufficiently long to impress a corresponding character 

 on the vegetable and perhaps the animal productions of each. 



LINN^AN SOCIETY. 



Jan. 18, 1831. Edward Forster, Esq. in the Chair. 



The paper read was entitled, A Notice of several recent Disco- 

 veries in the Structure and CEconomy of Spiders ; by John Black- 

 wall, Esq., F.L.S. The object of the author's particular investi- 

 gation is the Clubiona atrox, of whose habits, and mode of fabri- 

 cating its residence and its snare, he gives a detailed and curious 

 account. 



ASTRONOMICAL SOCIETY. 



Nov. 12, 1830. The following communications were read: 



I. Ephemeris of the occultations of a Tauriin 1831, for ten Eu- 

 ropean Observatories, by Mr. Maclear. 



I I. Practical rules for the approximate prediction of occultations, 

 by Mr. Henderson. 



III. A note by Mr. Gompertz, to a paper by M. Kreil on the 

 rectification of the equatorial. 



IV. Occultations observed at Boston, Massachusetts, by Mr. 

 Robert Treat Paine. 



Mr. Paine gives the mean solar time of six complete observa- 

 tions of Aldebaran (immersion and emersion), five at Boston and 

 one at Nantucky, with a 3J feet achromatic telescope, and a mag- 

 nifying power of 60: the telescope was adjusted on a star. " In 

 four of the observations nothing remarkable was noticed, except 

 that when the immersion or emersion took place on the enlightened 

 limb, the star became so tremulous as to cause an uncertainty of 

 I s or 2 s ; but in two other instances (one at emersion and the other 

 at immersion) the star did actually appear projected upon the face 

 of the moon for about 2 s ; and the light of the star was in both in- 

 stances very much more brilliant than usual, although the emersion 

 took place about sunset, and the immersion while the sun was above 

 the horizon." 



" On September 17, 1829, about 10 s before immersion, [the star 

 spread out, and appeared like a star viewed through a telescope not 

 adjusted to distinct vision, and then faded away so gradually that 

 its final disappearance could not be noted with greater precision 

 than 3 5 or 4\ The same appearance was seen by another gentleman 

 observing at a place 2| miles distant from me." 



V. Observations upon the period of the variable star /3 Lyrse, by 

 Mr.W. R. Birt. 



In the year 1784-, Mr. Goodricke remarked that /3 Lyrse varied 

 from the third to the fifth magnitude, and fixed the period of this 

 variation at 6 d 9 U . On the 22d May, 1830, Mr. Birt commenced a 



series 



