490 A. E. Verrill — The Bermuda Islands. 



between the reefs. Ordinary tides rise from 3^ to 4 feet, but the 

 spring tides may rise 5 feet, and in gales of wind sometimes 7 feet. 

 In Harrington Sound there is usually only 6 to 8 inches of tide, seldom 

 a foot. Near the shores the tidal currents run in various directions, 

 often varying according to the winds. 



In 1666, the Royal Society of London (founded in 1662) sent to 

 Mr. Richard Norwood, the surveyor, a long series of questions con- 

 cerning these islands and their productions, whale fishing, etc. 

 Many of these were answered in a letter from Mr. Richard Stafford 

 (later Judge Stafford), July 16, 1668. Mr. Norwood replied to the 

 questions concerning the moon and tides, in a letter of June 18, 1667. 

 Both letters were published in the Philosophical Transactions, vols. 

 II, III. 



In his letter Mr. Norwood gives several facts as to the tides. He 

 stated that the tides commonly rise 4 feet, at spring tide 5 feet, but 

 that they are variable according to the wind ; in calm weather the 

 flood tide sets from the southeast ; high water occurs at 7 o'clock 

 on the "change day." 



16. — The Soil ; its Origin <<nd Composition. 



With the exception of the black peat or muck of the swamps and 

 marshes, all of the soil of the islands has been produced as an insolu- 

 ble residue, or impurity, left after the solution of the limestones and 

 shell-sands of the islands by rain water, but it is usually mixed with 

 more or less disintegrated limestone, and some organic matter. 



These rocks and sands always contain a small amount of earthy 

 impurities, often not more than 0.5 of one per cent., and seldom more 

 than one per cent., which consists mainly of clay and iron oxide, and 

 Avith a little phosphate of lime, potash, etc., to which the soil owes 

 its fertility. 



This process of forming soil is a very slow one, and indicates, as 

 well as anything else, the long period of time that has elapsed since 

 the Bermudas became dry land. The average thickness of this soil 

 has been variously estimated at from one to two feet, which would 

 require the destruction of at least 100 to 200 feet of limestone. (See 

 under Geology.) 



Where the decomposition has been complete, this soil is a reddish 

 clay, the color being due to an excess of iron oxide, but in most 

 places the clay soil is mixed with considerable shell-sand, or grains 

 of undecomposed rock. In many places the latter forms the greater 



