Natural History, %c. 643 



ment of winter, on account of the operation of the drains and 

 improvements before mentioned, more of the water afforded by 

 dissolving snows and cold rains in winter will necessarily be absorbed 

 by it ; and in the end of February, however dry the ground may 

 have been at the winter solstice, in the end of February, it will 

 almost always be found saturated with water ; and as the influence 

 of the sun is as powerful on the last day of February as on the 

 1 5th of October, and it is the high temperature of the ground in 

 the latter period which occasions the difference of temperature in 

 those opposite seasons, Mr, Knight thinks it cannot be doubted, that 

 if the soil be rendered more cold by the absorption of water at nearly 

 the freezing temperature, the weather of the spring must be, to some 

 extent, injuriously affected *. 



11. ON THE EARTHQUAKE AT ODESSA ON THE 26iH OF NOVEM- 

 BER, 1829. (M. Hauy). 



On the 14th (26th) of November, 1829, at3h. 58 minutes in the morn- 

 ing, M. Hauy was awakened by slight vibrations, which appear to 

 have been the beginning of the earthquake. They increased during 

 two-thirds of a minute, and then a severe shock ensued, which lasted 

 some seconds. The vibrations then abated, but increased again for 

 a minute, when a second very severe shock, which was much stronger 

 than the first, was felt. After this, the motion decreased at first, 

 and was next again about twelve or fifteen seconds on the increase, 

 when the third shock took place. It was weaker than the first, and 

 lasted only some moments. A new interval followed, in which a 

 diminution of the oscillatory motion was again succeeded by an aug- 

 mentation of it, which had lasted about a quarter of a minute, when 

 the fourth and last shock took place, which was equal in intensity to 

 the third, and lasted about three or four seconds. The tremulous 

 motion, although constantly decreasing, continued about one minute 

 and a half longer. At 4h. '2' 2" every thing was again at rest ; 

 during the four minutes which the earthquake lasted, the trembling 

 motion continued without interruption. The cracking of a wooden 

 partition in the bed-room enabled M. Hauy to count 152 complete 

 oscillations in the space of thirty seconds. He frequently observed 

 the barometer during the phenomenon, but could not discover any 

 change ; neither did M. Challaye, the French Consul, who observed 

 the barometer almost without intermission, observe any motion in 

 the mercurial column. During a good part of the night, the weather 

 was calm, the sky overcast, and the thermometer at R. (32 F). One 

 of M. Hauy's friends, Dr. Hennan, saw, to the eastward, a strong arid 

 very distinct brightness in the sky, analogous to an aurora borealis, 

 veiled, however, by the clouds which covered the atmosphere. The 

 visible maximum of the intensity of this light was at the horizon ; 



* Trans. Hort. Soc. Loud., voL vii. p. 4. 



