4i*!(> Intelligence and Miscellaneous Articles. 



production*. Although this may be the ordinary circumstance, it 

 is not always the case. More than once vessels have been carried 

 along by the wind, and their images shifted in a similar manner. 

 This phsenomenon is often remarked on the Black Sea, from Odessa. 

 The accounts of the observations of Woltmann near Cuxhavenf, and 

 of Vince at RamsgateJ, leave no doubt with respect to this fact. The 

 following is a similar instance, observed at Nyon in the summer of 

 1848 by M. Thury, formerly professor at Lausanne, and which is 

 still better characterized than the previous ones. 



It was twenty minutes to 8 o'clock, a.m. The bise had raised 

 foaming waves upon the lake. In the south-east some vapours 

 floated on the horizon : the sky in every other part was of a clear 

 blue. By the aid of a good telescope of 0*068 millim. aperture, and 

 which magnified thirty times, M. Thury descried on the heights of 

 Coppet, in the direction of Geneva, the two lateen sails of a bark 

 the hull of which was not at all visible. A little below the lower 

 extremity of these sails, the commencement of their image was seen 

 inverted. This incomplete image terminated abruptly on the agitated 

 and clear surface of the water. The space which separated the sails 

 from their image was of a uniform greenish-blue colour. The lowest 

 strata of air undulated in a very perceptible manner. 



This last circumstance, and the situation of the image below the 

 object which it represented, are proofs that the phsenomenon resulted 

 from a greater heating of the atmosphere in the lower strata than in 

 the more elevated regions. But for the hull of the vessel to be in- 

 visible, and for the contours of the objects, examined with a telescope 

 at fourteen metres above the level of the water, to be perfectly well- 

 defined, the warmest zone of air must have terminated under the 

 wind toward the base of the sails, that is to say, at three or four 

 metres above the surface of the lake. The existence of a zone thus 

 limited is therefore possible with the bise blowing sufficiently strong 

 during the few minutes necessary for the observation. This fact 

 recalls the persistence of the undulation in the strata of air which 

 are close to the roofs and the ground during the warm hours of a 

 summer's day, or above the chimneys in winter, notwithstanding the 

 agitation produced by intense winds. 



II. On blue rays. — On the 30th of November last, a little before 

 sunrise, M. Thury perceived at Nyon, above the mountains which 

 border the lake on the east, horizontal strata of light clouds tinged 

 with a beautiful yellow. The sky, seen in the spaces between them, 

 was of a deep azure colour. Toward the point of the horizon where 

 the sun was about to appear, a dark blue ray rose divergingly up to 

 a great height, and occupied a space in which no cloud was percep- 

 tible. This appearance vanished after two or three minutes. 



Dr. Gosse has found, among his father's papers, the account of an 

 analogous observation made at Lyons toward the end of the last 



* Lehrbuch der Meteorologie, vol. iii. p. 87. — Cours Complet de Meteoro- 

 logie, translated by Ch. Martins, p. 4?2. 



t Gilbert's Annalen der Physik, vol. iii. p. 397. 

 J Philosophical Transactions, 1799, p. 13, 



