318 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



Oregon and Pu^et's Sound, naval officers in charge of sur- 

 veying parties have "been constantly at work aiding to com- 

 plete charts of the coasts. 



In addition to the regular work of the year, a system of 

 dredging and general examination of the oyster-beds of 

 Chesapeake Bay has been carried on to obtain information 

 for the promotion of this most valuable interest. The data 

 obtained are being examined and discussed by Mr. W. H. 

 Dall. 



A review of the work accomplished by English hydrog- 

 raphers during the past year shows no falling off in either 

 quantity or quality of results attained as compared with pre- 

 vious years. Besides a large amount of subsidiary w r ork at 

 various points on the shores of Great Britain, where changes 

 in the bottom have necessitated corrections on the charts, 

 the central part of the English Channel, from the neighbor- 

 hood of Dunseness and the Varne Shoal to the Owers, has 

 been re-sounded, the surveys made during the last century 

 bein<r very deficient in details. The river Shannon has been 

 very completely re-surveyed, and the shoal ground in the 

 neighborhood of the Smalls and Bishops rocks has been thor- 

 oughly examined. 



In view of the increasing importance of the Red Sea as a 

 thoroughfare, the surveys which have been going on there 

 for some years have been continued, the charts of Musawwa' 

 Channel having been completed during the past season by 

 the officers of H.M.S. Fawn. Data obtained by the same 

 officers regarding the approaches to the Suez Canal indicate 

 that, while a depth of 28 feet may still be carried to within 

 the breakwater on approaching the northern terminus of the 

 canal, a deposit from the Nile is taking place, amounting to 

 about one foot annually, and extending over the whole area 

 of the approaches to Port Said. 



In this connection it may be mentioned that M. de Lesseps 

 has recently communicated to the French Academy of Sci- 

 ences the results of tidal and current observations, made at 

 several stations on the Suez Canal since 1871. It appears 

 that from May to October the prevailing winds are from 

 north and northwest, raising the mean level of the water at 

 Port Said and depressing it at Suez. This difference of level 

 which amounts at times to about 1C inches, causes a constant 



