FROM TBE EDDYSTONE GROUNDS TO START POINT. 379 



VIT. Fine Sand. Material which passes through O'o mm. sieve 

 and when stirred up with sea-water settles in one 

 minute. 

 VIII. Silt, liemaius in suspension at the end of one minute. 



The designations here adopted seem to agree very well with the ideas 

 generally connected with the respective terms, and it would be a great 

 advantage if these terms could in future be used in the exact senses 

 proposed. 



In determining the texture of a sample by the use of a series of 

 sieves it is necessary, in order to obtain constant results, that a con- 

 siderable quantity of material be examined, especially in the case of 

 coarse and mixed deposits. My practice was to sieve the quantity 

 which was contained in a bottle of about 800 cc. capacity. 



After trials of various methods the following was adopted as the 

 readiest and most convenient way of obtaining satisfactory results. 

 The finest sieve was placed in a vessel somewhat larger and deeper 

 than itself, so large in fact that the sieve could be conveniently worked 

 about with the hand. Sea-water was then poured into the surrounding 

 vessel until the sieve, standing in it, was nearly full. Small portions 

 of the sample were placed in the sieve and worked about until all the 

 fine sand and silt were washed out. In the case of very muddy samples 

 the process was repeated in a second quantity of water. The portion 

 remaining on the sieve was washed through the other five sieves 

 successively in a similar way, commencing with that of largest mesh. 



The mixture of fine sand and silt was separated by stirring it up well 

 in the sea-water, allowing it to stand for one minute, and then pouring 

 the water off. Where two washing waters had been used, the second, 

 with its contents, was poured on to the first sample of fine sand, 

 the whole stirred up again, left to stand one minute, and the water 

 poured off. The water in which the silt was suspended was allowed 

 to settle for at least twenty-four hours and the clear portion then 

 drawn off. The remainder was passed through a weighed filter paper 

 and the silt collected. 



The samples of gravel and sand on the various sieves and of silt on 

 the filter paper were all dried at a low temperature and weighed, the 

 results being expressed as percentages of the total weight. The tex- 

 tures of the various samples examined are shown in Table II., p. 525. 

 One of the most curious features brought out by this method of 

 examination of the texture of the bottom-deposits is the fact that nearly 

 every sample of the coarser deposits is composed of a mixture of coarse 

 gravel and fine sand or mud, material of intermediate texture being 

 present in small quantity only. Thus sample 84 is a mixture of coarse 



