206 PHILOSOPHICAL TRANSACTIONS. [aNNO 1675. 



Emersion begins gh. 12m. 30s. 



End of the eclipse 10 20 



Duration of total darkness 1 29 46 



Total duration of eclipse 3 38 10 



The clock corrected by altitudes of the stars. 



The Improvement of Cornwall by Sea-sand. By Dr. Dan. Cox. !N° 113, p. 293. 



This sand, employed in the agriculture of Cornwall, is commonly at or near 

 the sea shore. To distinguish it from what is useless, observe, that the wash 

 of the sea rolls and tumbles stones and shells, &c. one over another, whose 

 grating makes this sand. If the matter be shelfy, that is the grating of stones, 

 it is of small value. But if it be shelly, then it is good. Of this shelly sand 

 there are three colours. About Plymouth, and the southern coast, the sand is 

 bluish or grey like ashes ; which I conceive to be from the breaking of muscles 

 chiefly, and oyster-shells mixed with it. Westward near the Land's-end, the 

 sand is very white, and in Scilly, glistering. This I think happens from the 

 mouldering of moor-stones, or a kind of free-stone mingled with very white 

 shells called scollops. On the north sea, from about Padstow and eastwards to 

 Lundy, the sand is rich and of a brown reddish-yellowish colour, and is mostly 

 of the broken shells of cockles ; which I guess to be of that colour there, from 

 the wash of the Severn, which falls very dirty into the Severn sea, and perhaps 

 that accretion of the shells may be tinged thereby. 



Now besides these colours of sands, there is also a difference in the size of 

 the grain. Even in the same harbour of Plymouth in some coves, it is very 

 small, in others long grained, and is used variously for divers purposes. It is 

 said that the small is best for the tenant, who only takes to tillage for four years, 

 because it works sooner, and yields a speedy return. The larger grained is said 

 to be better for the landlord and the land ; because it lasts longer in the ground, 

 and makes the pasture afterwards the better. 



Of all these sands, the best are accounted, as to colour, first the reddish, 

 next the blue, then the white. As to kinds, the most shelly and the coralline 

 are best : and that which is taken up from under the salt-water, either by 

 dredges, or being left open by the ebbing of the tide. The blown sand is ac- 

 counted of no use. And generally, if sand be well drained of the salt-water, 

 so that it may be more conveniently carried, it is better than that which has lain 

 long drying in the sun and wind, which takes off'much of its virtue. 



These useful sands are carried by lighters as far up into the country as the 

 tides will serve to that purpose, and there they are cast on shore. When brought 

 home, it is spread on the ground intended for wheat, or usually in the first crop 



