368 Secchi on Magnetic and Atmospheric Perturbations. 



have belonged to a " similar animal," which he designated 

 Arcliceopteryx lithographica. For various reasons drawn from 

 comparative anatomy, M. Wagner rejects the idea of the crea- 

 ture having been a variety or new kind of bird. He says " a 

 reptile with the simple tarsal bone of a bird, and with epider- 

 mic structures presenting a deceptive appearance to bird's 

 feathers, is far more comprehensible to me than a bird with the 

 pelvis and vertebral column (especially the long slender series 

 of caudal vertebras) of a long tailed Pterodactyl, and with a 

 perfectly different mode of attachment and of feathers." The 

 idea of a " deceptive appearance'" in the feather is negatived 

 by Yon Meyer, who states that in his specimen the fibres of the 

 vane can be distinctly traced, and even the small barbules with 

 which they are beset. M. Wagner named the fossil which he 

 examined Griphosaurus (Enigma-hzard), and it does not seem 

 that Von Meyer has any reason for supposing the creature to 

 which his feather belonged was of a different nature, although 

 he has given it a different appellation. M. Wagner thinks the 

 discovery of the new fossil may explain the foot prints in the 

 Trias, which have been ascribed to birds, and Yon Meyer re- 

 marks that in 1824 he pointed out the danger of too closely 

 following Cuvier's theory that a similarity of particular parts 

 indicated a similarity of other parts, or of the whole. 



SECCHI ON MAGNETIC AND ATMOSPHERIC 

 PERTURBATIONS. 



In a letter to the French Academy, the distinguished Roman 

 observer Secchi, gives a summary of the conclusions he has 

 arrived at respecting the connection between magnetic pertur- 

 bations and atmospheric movements. This he considers esta- 

 blished, first, by the great variations of magnetic elements, and 

 especially in the intensity of the horizontal force, on the occur- 

 rence of storms ; secondly, by the irregularities which accom- 

 pany periods of squalls ; thirdly, by the great depression of the 

 bifilaire,* and the variations of other instruments which precede, 

 or follow immediately, great changes in the weather ; fourthly, 

 by variations of intensity corresponding with variations of the 

 winds ; fifthly, by the aurora borealis, which, considered as a 

 signal of variation in wind and weather, belongs to the class 

 of phenomena under discussion. 



* The "Bifilaire," or Bifilar, is a Horizontal Force Magnetometer, so called 

 from the magnetic bar being suspended by a double thread of silk or wire. Its 

 object is to measure variations in the intensity of tbe horizontal component of the 

 earth's magnetic force. 



