8 



The National Geographic Magazine 



Geodetic Association, the Coast and Geo- 

 detic Survey supervises the maintenance 

 of two astronomical observatories estab- 

 lished exclusively for the purpose of 

 observing the variation of latitude. 



The Tidal Division has made good 

 progress not alone in the reduction of 

 tidal observations and in the publica- 

 tion of predictions, but has devoted at- 

 tention to the theoretical investigations 

 needful in this important and difficult 

 branch of applied science. 



The Coast Pilot Division issued last 

 year a new Coast Pilot of Southeastern 

 Alaska. It has in preparation another 

 volume of the Pacific coast from San 

 Diego to Puget Sound, and has just 

 completed, in the field, an examination, 

 of the coast from Eastport to Point 

 Judith. 



The triangulation along the 98th 

 meridian is progressing with remarka- 

 ble rapidity in consequence of carefully 

 devised plans, which prescribed the 

 method to be followed along efficient 

 and economical lines without any sacri- 

 fice of accuracy. During the last season 

 an axial distance of about 400 miles was 

 measured, which in itself constitutes an 

 arc of no mean extent. 



Speed trial courses based on the tri- 

 angulation of the Survey have been 

 laid out in various localities at the re- 

 quest of the Navy Department. 



At the request of the states of Penn- 

 sylvania and Maryland, a remarking of 

 Mason and Dixon's line has been un- 

 dertaken b} _ the Survey in cooperation 

 with commissioners from those states, 

 and the work is nearly finished. 



Two officers of the Survey were ap- 

 pointed by the United States Supreme 

 Court to take part in the remarking of 

 the disputed boundary between Virginia 

 and Tennessee, and this work has 

 reached a conclusion. 



The work of determining trigonomet- 

 rically light-houses and beacons along 

 the coasts of Maine and Massachusetts 

 erected or rebuilt since the original tri- 



angulation was made, and elsewhere, 

 was taken up and a junction was made 

 between the secondary coast triangula- 

 tion near Beaufort, South Carolina, and 

 the oblique arc near the northeastern 

 corner of Georgia. 



Revisionary h}-drographic surveys 

 were made in Nantucket Sound, in New 

 York Bay and in the Chesapeake Bay 

 and its tributaries, as well as on the Gulf 

 coast, and new hydrographic develop- 

 ments were made on the coasts of Porto 

 Rico. 



PORTO RICO 



In the survey of that island great 

 progress has been made. The entire 

 shoreline of Porto Rico, Vieques, and 

 Culebra Islands has been mapped. A 

 triangulation extending from Mona Is- 

 land on the west to St Thomas on the 

 east has been made. It encircles the 

 island of Porto Rico and traverses it in 

 the direction from San Juan to Ponce. 

 Surveys of all the ports have been made 

 and are either published or in process of 

 publication. A corrected general chart 

 of Porto Rico and adjacent waters em- 

 bodying all the work done has been en- 

 graved on copper and is in the printer's 

 hands, and a series of 4 charts on a scale 

 of 1 : 100,000 is rapidly being prepared 

 and two of these will soon be issued. 

 Tidal and magnetic observations have 

 been made at numerous points. The 

 harbor charts which have been pub- 

 lished or which are about to appear are 

 those of San Juan, Fajardo, Culebra, 

 Port Mulas, Bahia Honda, Ponce, Guy- 

 anilla, Guanica, and Mayaguez. 



The hydrography of by far the greater 

 part of the south coast has been finished, 

 and great progress has been made on 

 the west coast, but more especially on 

 the east coast, which is the scene of the 

 coming naval maneuvers. There an 

 area of no less than 400 square miles 

 has to be sounded out with minute accu- 

 rac}', owing to the importance of the 

 locality and the irregularities of the 



