Academy of Sciences in Paris. 559 



half-past eight. It appears that, by comparing the declination at 

 this hour with that observed at five o'clock, the horizontal needle 

 had been affected by the Aurora to the extent of 1 16' 39". The 

 instruments with which these observations were made are of such 

 exactness, as to render it certain that the errors are not more than 

 five seconds at the utmost. The effect of the Aurora on the needle 

 of inclination was not less decided ; but the variations of the latter 

 had no connection with, or analogy to, those of the needle of declina- 

 tion. Thus sometimes the inclination increased while the declination 

 diminished; and at others both increased or decreased together; 

 and several times one of the needles was almost stationary at the 

 moment of the greatest variations being observed in the other. On 

 the 7th of January, the least inclination was at ten minutes past 

 two in the afternoon, and the greatest at thirty-five minutes past 

 seven. The total variation was twenty-one minutes, while at this 

 season the diurnal variation scarcely exceeds one minute. At the 

 moment when the Aurora was at its height, the atmospheric 

 electrometer of the Observatory did not give the least sign of 

 electricity. 



Tides in the Atmosphere. At the meeting of the 3 1st of January, 

 M. Murphy communicated to the Academy a variety of observations 

 tending to prove that there exists an analogy between the lunar in- 

 fluence on the tides and the atmospheric temperature. This analogy 

 is most apparent at the equinoxes and solstices. M. Murphy stated 

 that during the last winter the lowest degree of temperature, both in 

 London and Paris, was in each period of frost the day or day but 

 one after one of the lunar quarters. 



BOTANY. 



Kelkoa. On the 31st of January, a report was read to the Aca- 

 de*mie des Sciences respecting the kelkoa or planera, a tree growing 

 on the coasts of the Caspian and Black seas. This tree, which was 

 erroneously distinguished in France by the name of Siberian elm, 

 received the name of planera from Gmelin, who so called it in 

 memory of Planer, Professor of Botany at Erfurth. The report 

 states, that the wood of this tree being hard, elastic, and not easily 

 injured by damp or worms, may be advantageously used by car- 

 penters and cabinet-makers ; while the luxuriance of its foliage, 

 which is not liable to injury from caterpillars, who reject it as food, 

 renders it a desirable substitute for the elm in avenues. It has also 

 another advantage over the elm, in not being subject to the cankers 

 by which the trunk of the latter is so frequently destroyed. Seeds 

 may readily be procured from Tiflis, or the planera may be grafted 

 on the elm, which is the easiest mode of propagating it. 



Maturation of Fruit. 21st of February. A report was pre- 

 sented to the Academy on several memoirs relating to the pheno- 

 mena observable in the ripening of fruits. Various opinions, in 



