794 



SCIENCE 



[N. S. Vol. XXVII. No. 69S 



observatories were afforded to all investigators 

 who desired to make standardization com- 

 parisons of their instruments ; and in response 

 to numerous requests information, or observa- 

 tional data, was furnished for practical ap- 

 plication or for use in special investigations of 

 terrestrial magnetism and allied phenomena. 



Appendix No. 6, constituting the concluding 

 portion of a manual of tides, treats of the 

 flow of water, of river tides, tidal currents, 

 permanent currents, annual inequality, lake 

 tides, seiches, and miscellaneous tidal matters. 



Charts of concurrent lines are given for the 

 principal marginal waters along the Atlantic 

 Coast of the United States. The numbers 

 upon these lines show the times of the maxi- 

 mum flood current. 



The dependence of the permanent ocean cur- 

 rents and the annual height in equality upon 

 the prevailing winds is briefly pointed out. 

 Seiches are shown to exist in harbors and 

 other tongues of water, as well as in lakes; 

 but their character is fundamentally different 

 in some respects. 



The analyses of observations upon the tides 

 of Lake Superior show that they follow closely 

 the equilibrium theory although the range is 

 only IJ inches at Duluth and one third inch 

 at Marquette. 



In Appendix No. 7 is given a detailed de- 

 scription with appropriate illustrations of the 

 Long Wire Drag, a device for detecting erratic 

 obstructions of small extent in navigable 

 waters. The method of operating can be 

 understood from the simple statement that the 

 drag is a wire varying in length from 480 

 to 1,400 feet, supported at suitable intervals 

 and maintained at any desired depth below the 

 surface of the water. This drag is towed 

 over any given area by launches, and in the 

 area so searched no elevation of the bottom 

 above the depth at which the wire is suspended 

 can escape detection. Buoys floating at regu- 

 lar intervals above the drag indicate to ob- 

 servers in the launches when and where an 

 obstruction is touched, and the spot so indi- 

 cated is then accurately determined. 



This method of sweeping has proved a sure 

 means of detecting pinnacle rocks and similar 

 erratic obstructions which heretofore have 



eluded the hydrographic surveyor, since it is 

 almost impossible to discover them by lines of 

 soundings with the lead. Only the navi- 

 gator in whose hands rest many lives and 

 much property can realize the relief from 

 mental strain that comes from knowing that 

 the water in which he is sailing is absolutely 

 free from hidden dangers or that every 

 menace is charted. The device has proved 

 very satisfactory under widely varying condi- 

 tions and marks a decided advance in marine 

 surveying. 



This report, or any one of the Appendices, 

 numbered 3 to 7, may be obtained by interested 

 persons, free of charge, upon application to 

 the Superintendent of the Coast and Geodetic 

 Survey, Washington, D. C. 



BERMUDA BIOLOGICAL STATION FOR 

 RESEARCH 



By arrangement with the Bermuda Natural 

 History Society, the Station for Research at 

 Agar's Island will be open for about seven 

 weeks this summer. There are accommoda- 

 tions for a limited number of instructors or 

 research students in either zoology or botany. 



Members of the expedition will sail from 

 New York on the steamer Bermudian (Quebec 

 Steamship Co.) at 11 a.m., on Tuesday, June 

 16, arriving in Bermuda, June 18, and will 

 return on August 5, reaching New York 

 August 7. Those who can not sail on June 

 16, may do so two weeks later, Jime 30. 



The expense will be $110 for first-class 

 passage from New York to Bermuda and 

 return, and for board and lodging at the 

 islands six weeks and sis days. For the shorter 

 time — four weeks and six days — the expense 

 will be $90. Payments are to be made to the 

 undersigned, fifty dollars on or before June 1,. 

 the balance on arriving in Bermuda. 



For further information apply to 



E. L. Mark 



109 Ieving Street, 

 Cambeidge, Mass. 



CONFERENCE ON THE CONSERVATION OF 

 NATURAL RESOURCES 

 In a sense the federal and state scientific- 

 work to date culminates in the Conference om 



