JcLY 10, 1903.] 



SCIENCE. 



37 



pleted has been adopted as a standard of 

 reference for all future trigonometric work 

 of the survey in so far as purely geographic 

 and topographic purposes are concerned 

 and this great country will soon have a 

 homogeneous system of geographical co- 

 ordinates which will sei've, it may be con- 

 fidently believed, for all times to come, the 

 manifold uses to which it can be put by the 

 national government, by the states and 

 municipalities and by engineers and sur- 

 veyors. 



Intimately connected with the question 

 of the dimension of the earth is that of its 

 figure, and here the pendulum will play an 

 important part. The earlier work of the 

 survey with the pendulum has its chief 

 value in showing the limitations of the 

 methods and appliances used. Much 

 simpler and more reliable apparatus was 

 introduced some years ago and has given 

 satisfactory results. The apparatus was 

 used not only in relative gravity obseiwa- 

 tions in this country but for the purpose of 

 connecting our own base station with the 

 English and continental ones, a work which 

 was rendered possible by a subvention from 

 the International Geodetic Association. 

 At the present time no gravity work is be- 

 ing done, it being deemed advisable to study 

 the deflections of the plumb line as brought 

 oiit by a i-eduction of the triangulation to 

 a common system. When that has been 

 done the pendulum may perhaps serve to 

 indicate relations between any anomalies 

 that may develop in particular localities 

 and the foi-ce of gravity in the same re- 

 gions. 



Closely related to these geodetic features 

 of the work of the Coast Survey are the 

 astronomical determinations and especially 

 tlie determinations of telegraphic longi- 

 tudes. Long ago the survey determined 

 the diflference of longitude between Europe 

 and this country by means of the Atlantic 



cable. It has covered this country with a 

 well-adjusted network of stations and is 

 now stretching its determinations westward 

 across the Pacific. The longitude between 

 San Francisco and Honolulu is being de- 

 termined while we are gathered in this 

 hall, and the observers are getting ready 

 to meet the new cable at Guam witliin a 

 few \\eeks in order to extend the work to 

 jManila. Manila has been the base station 

 for our observers in the Philippines, who 

 have been for two yeai-s busily engaged in 

 utilizing the local cables and land telegi-aph 

 lines for similar purposes. The geographic 

 explorations in Alaska, the boundary ques- 

 tion and the surveys in that territory call 

 for further and immediate extension of 

 this work there. But it requires no great 

 stretch of the imagination to believe that 

 the wireless method of sending signals wiU 

 at no distant day make us independent 

 of cable or telegraph lines as far as longi- 

 tude work is concerned, and for this pur- 

 pose the method would be an ideal one. 

 Last summer, as an experiment and with 

 short-distance instruments, a chronometer 

 on one of the survey vessels transmitted 

 automatically its half-second beats to a 

 shore station over sixty miles away, where 

 they were received and automatically re- 

 corded on a moving tape. 



In the leveling of precision we have still 

 another class of work belonging to the 

 geodetic function of the survey. Here the 

 aim of the survey is to furnish a series of 

 primary bench marks properly related to 

 the mean sea level of the Atlantic, Gulf 

 and Pacific coasts which shall serve to cor- 

 relate the thousands of miles of levels 

 which have been and are being run by the 

 railways, the canal enterprises, the Geolog- 

 ical Survey and the engineers of the United 

 States Army for many different purposes, 

 but all for the common good. It is pleas- 

 ant to record that through the cooperation 



