June I, iS88.] 



SCIENTIFIC NEAA^S. 



509 



series form a panorama, showing the development of the 

 whole chain of the Pyrenees as seen from the Pic du 

 Midi, the plates having been exposed at sunrise, before 

 the rays of the sun had touched the almost unbroken 

 bed of clouds which filled the valleys, from which 

 only the highest points of the chain emerged. The bed 

 extended in this case from the ocean to the eastern spur 

 of the group. As the sun rises, it gradually aftects this 

 cloud-bank and draws it upward, and then is seen the 



Janssen aptly likens to the " surges of a tempest-tossed 

 sea ;" behind it is the Arbizon, and on the horizon the 

 groups of the Pic Poset and of the Clarabide and the 

 Nethou. 



Closely connected with these phenomena of the cloud- 

 bank are others whose interesting meteorological causes 

 would amply repay further investigation. Sometimes 

 the clouds are entirely dissipated by the action of the 

 sun ; at other times they rise and form another cloud- 



t^:^^^: 



^-•^^^^v 



4r 



Photograph of Clouds, taken by MM. Janssen and Laji.^zguere at the Pic du Midi. 



phenomenon shown in another of the photographs, in 

 which the whole chain of the Pyrenees presents the 

 aspect of a stormy sea, the occasional summits emerging 

 from the cloud billows bearing a striking resemblance to 

 islands. Sometimes, as the cloud-bank rises, currents 

 of warmer air piercing through it, carry off some of the 

 nebulous matter, and strange flock-like forms arise from 

 the depths of the mass. In the photographs of the chain, 

 the Pic de la Picarde appears in the foreground, rearing 

 its lofty head above the bank of clouds which M. 



mantle at a much greater altitude ; or yet again they 

 resolve themselves into a fog, which envelops the whole 

 of the chain, completely hiding it from view. These 

 different phenomena are due not only to the meteorolo- 

 gical conditions of the regions where they occur, but also 

 to the action of those foreign elements, brought by the 

 winds, which invariably exert a strong influence on 

 meteorology. M. Janssen has witnessed the results of 

 this influence on several occasions, notably during 

 his stay at the elevated station of Simla, in the Himalayas, 



