266 



SCIENCE. 



[N. S. Vol. XV. No. 3'2. 



ware and Chesapeake bays, and the Santa 

 Barbara channel course was extended. 



In addition to other field and office work, 

 continuous tidal stations were maintained 

 in this country at 6 stations and at 1 in 

 the Philippines, and tide tables for 1902 

 were jDublished, giving predictions for 70 

 principal and about 3,000 subordinate sta- 

 tions throughout the world. 



During the year the Coast Pilot relating 

 to southeast Alaska was thoroughly revised 

 in the field and prepared for the printer. 

 The field revision of the Coast Pilot between 

 San Diego and San Francisco was com- 

 pleted and new editions of sections relating 

 to the Atlantic coast were published, and 

 the revision and issixe of other numbers are 

 in progress. 



Strict business methods are not often 

 associated with the measurement of the 

 bases of a great trigonometrical survey. 

 From the literature on the subject it ap- 

 pears that in the endeavor to attain a high 

 degree of accuracy fLnancial considerations 

 have been subordinated to the scientific and 

 experimental. The conduct of the measure 

 of the nine bases along the ninety-eighth 

 meridian was an exception to this rule, and 

 Appendix No. 3, which describes the 

 methods and results has an added interest 

 of novelty. This was the first campaign 

 of a party organized solely for the meas- 

 urement of bases. A great gain in economy 

 and time was accomplished by taking ad- 

 vantage of the skill acquired by the party 

 by the frequent repetition of the same oper- 

 ations. After a thorough study of former 

 measures a standard of accuracy was deter- 

 mined upon, anc] the operations so planned, 

 by strengthening some points in the 

 methods, that the number of measures 

 could be reduced and certain refinements 

 omitted. These bases form part of the 

 chain of triangulation which it is pro- 

 posed to extend along the ninety-eighth 

 meridian, in both a north and south direc- 



tion from the transcontinental chain, to 

 the boundaries of the United States. It 

 will include an arc of 23°, and together 

 Avith the transcontinental triangulation as 

 the backbone will form one of the ribs of 

 the main framework for the control of all 

 the triangulation in the United States. The 

 Mexican Government has already in prog- 

 ress a system along the same meridian 

 ■which, it is expected, will extend the arc 9° 

 in latitude, and it is also possible for the 

 Canadian Government to extend the arc far 

 to the northward. Appendix No. 6 treats 

 of the completed portion of the work in 

 Kansas and Nebraska. 



In connection with the general magnetic 

 survey which supplies the data for con- 

 structing the compass diagrams on the 

 charts, and furnishes the land surveyor the 

 information for correctly running his trav- 

 erse lines, observations were made at 374 

 stations in 30 States and Territories, in- 

 cluding Alaska, Porto Rico, Hawaii and 

 the Philippine Islands. In southeastern 

 Alaska places have been examined where 

 local magnetic disturbances affect the com- 

 passes of passing ships to such an extent as 

 to endanger navigation. 



A magnetic observatory has been estab- 

 lished in Maryland, and sites for others 

 have been selected in Alaska and Hawaii. 

 In addition to their regular work, these will 

 cooperate, at the formal request of the 

 German Government, with the interna- 

 tional magnetic work to be carried out dur- 

 ing the time of the various antarctic ex- 

 peditions which have been sent out from 

 Germany and Great Britain. 



Another piece of work of international 

 interest Avas executed by the Survey in 

 1900. Observations were then made with 

 the half second pendulum apparatus, de- 

 vised by the Survey, at several of the more 

 important European base stations, for the 

 purpose of connecting Washington, which 

 is used as the base for the American pendu- 



