352 



stalks 12 or 18 inches apart upon the rows. Early in July the plant 

 has usually acquired sufficient size to shade the ground and prevent 

 the further growth of grass, and the crop is then "laid by." It is 

 of the first importance that the land should have been kept perfectly 

 clear of weeds up to this time, and in a hot climate the task is often 

 a difficult one. 



Simultaneously with the cultivation of cotton, the cultivation of 

 Indian corn, sweet potatoes, &c., proceeds, in order to furnish food 

 for the negroes of the plantation, for the mules or other draught 

 animals, and for a sufficient number of hogs to yield meat for the 

 labourers. 



In middle Alabama the cotton plant usually commences flowering 

 early in June, and continues to bloom until frost kills it, bolls con- 

 tinuing therefore to form during several months. The earliest bolls 

 open, in ordinary years, from the 10th to the 15th of August, 

 when the "picking " season commences. This lasts until the cotton 

 is all gathered until January or even February, if a full crop be 

 made. The bolls continue gradually to open long after frost has 

 prevented the formation of any more. In picking the cotton from 

 the boll, surprising manual dexterity is shown by negroes accustomed 

 to the task from early youth. 



The seed cotton, as it is collected into large baskets by the pickers, 

 is carried to the "gin-house" of the plantation, and "ginned;" and 

 when enough of the clean fibre has accumulated, a day or two is de- 

 voted by a part of the hands to pressing it with the large wooden 

 " screw " into bales ready for shipment by river to the sea-port. 



XI. "Account of Experiments made at Holyhead (North Wales) 

 upon the Transit- Velocity of Waves through the Local Rock 

 Formations." By ROBERT MALLET, Esq.. C.E., F.R.S. 

 Received June 18, 1861. 



(Abstract.) 



These experiments were made by the author at the joint request 

 of the Royal Society and of the British Association for the Advance- 

 ment of Science, aided by grants from each of those bodies. 



Their object was to ascertain the transit rate or velocity of pro- 

 pagation of waves of elastic compression, analogous to those of na- 



