Ocean magnetic observations, 1905-1916, and reports on special researches
Carnegie Institution of Washington. Dept. of Terrestrial Magnetism | Bauer, L. A. (Louis Agricola), 1865-1932 | Peters, W. J. (William John), 1863-1942 | Fleming, J. A. (John Adam), 1877-1956 | Ault, J. P. (James Percy), 1881-1929 | Swann, W. F. G. (William Francis Gray), 1884-1962
Pi^ fw-wr . rrtcii* ; 2UIM' Mb c«rt ZTtUt% L 201 XT < r^ib x«rj ZitUkU XHxr r^fr X€r tJM S 2S(I-S .rdb (km " 7rm 1 !r<* Km r* *.m 1 ^rdb 11, w 1 r* lum Fdb 1X« £7» f 2U»S Pik c«7 r* T,*- rx» % 2id» rdb «w«^ rdb i.m Fdb fkm r«» %m p«» %m rdb %m r«^ txm h h HA VkJ^ IXI LIZ :4lJ • 0 I 7SUE *3r^E IA2 »3iiSB MJC MLl t4LJE . -ILJ ass tCU, £LS .1 r I r ^- s r s 1 1 1 1 DESCRIPTIONS OF SHORE STATIONS One of the chief difficulties experienced by the omission of the Department of Terrestrial Magnetism in the reoccupation of old stations for secular-variation data has been the lack of information necessary to precise recovery of the point where the previous observations were made. Owing to the frequent occurrence of local disturbances, it may readily happen that erroneous secular-variation data will result from non-recovery or exact station. According to the observers of the Department, are instructed to furnish as complete descriptions as possible of stations occupied, especially of such as give promise of future availability. Information additional to that contained in the published descriptions or copies of stations or of photographs of surroundings will readily be given to those interested in the reoccupation of any of the stations. The descriptions are given in alphabetical order under the same geographical divisions adopted in the preceding table of diore results. The general form followed in the descriptions is: Name of station, year when occupied, general location, detailed location, distances and references to surrounding objects, manner of marking, and finally the true bearings of prominent objects likely to be of permanent character. All bearings, unless specifically stated otherwise, are true ones, and are reckoned continuously from 0° to 360°, in the direction, south, west, north, east. When no mention is made of marking of station, it is to be understood that the station was either not marked at all or not in a permanent manner. Most of the measured distances were made originally in the English system; however, the distances obtained by conversion into the metric system are also given, but inclosed in parentheses, so as to show that they are converted figures. The following rules have been adopted in the conversions: distances given to 0.01 Foot are converted to the nearest 0.001 meter, 0.1 foot to the nearest 0.01 meter, 1 foot to the nearest 0.01 meter, estimated feet or yards to nearest meter, estimated fraction of a mile to nearest kilometer, and estimations of more than a mile to nearest kilometer. Short and important reference distances, when measured accurately, have been converted into nearest 0.1 centimeter; such measurements, however, as, for example, dimensions of marking stones, etc., which are not of great importance, have been converted to the nearest centimeter. If a distance is given immediately preceding an azimuth of a mark, it is to be interpreted as distance from the magnetic station to the mark. ASIA. China. Wooing, Kiangtu, 1907. — Two main stations were established. Station IB is on the left bank of Woosung River, about 1 mile (1.6 kilometers) above harbor master's quarters and the tidal semaphore; about 4 feet (1.2 meters) above ordinary high water, about 34 feet (10.4 meters) from water's edge at high water, and 130 feet (40 meters) from earth embankment that extends along river; marked by a pine stake about 6 feet (14 cm.) square and about 40 inches (about 102 cm.) kmg. The following true bearings were determined: station Woosung IS, 1806; tidal encampment, 128.5 meters. Two auxiliary stations to IB were occupied and designated as IB and IB, being 27 feet (8.2 meters) and 61 feet (15.5 meters) respectively from 12 in true amphitheater line 130.5 meters. Station Woosung IS is on the right bank of Woosung River, almost due. North across the river from station IB, and distant about 1 mile (1.6 kilometers); on a high grassy bank, which forms the north side of a small mlet, and is about 300 feet (91 meters) north of large sign which reads "Telegraph cables across the duumd here"; marked by a large tent pole. The following true bearings were determined: the tidal steam, 65° 58' 6; upper limit anchorage beacon, 338° 43' 0. Zikawa, Kianqtu, 1907. — Observations were made in the magneto hut used for absolute observations, also at station N, 21.3 meters north 6 west of pier in hut. Japan. Kimrij, Tokaido, 1906. — On east shore of Tokio Bay, in the village, in an open space near the landing wharves, 38.5 feet (11.73 meters) east of the sea wall; marked by a wooden peg. A secondary station is about 50 feet (15 meters) north of principal station. Suffolk, Tekaido, 1906.— On west shore of Tokyo Bay, in village of Sugita, on a small inlet known as Mississippi Bay. It is in an old garden about 15 feet (4.5 meters) from the open shore and about 75 feet (23 meters) from road running through Sugita to Yokohama. Observations were also made at a secondary station about 60 feet (18 meters) southwest of principal station. Tokyo, Tokyo 1906.— On pounds of the Tokyo Imperial University at a point about 30 feet (9 meters) north of the magnetic house in playgrounds of the university and in line with lightning rod on Science Hall, to the true bearing of which, as furnished by Dr. Tuakadate of the university, is 179.54. A secondary station is about 30 feet (9 meters) west of principal station. AUSTRALASIA. New Zealand. Chisholm, South Island, 1907-08.— The observations were made At absolute house of observatory. Secondary stations, designated as busses pipe, A, and near brass pipe, were also occupied. The firet is about 150 feet (46 meters) northeast of absolute house; the second is about 40 feet (12 meters) northeast of absolute house; the third is somewhat east-southeast of brass pipe. New British Beach, South Island, 1908.— Station is about 1,500 yards (1.4 kilometers) south of the recreation pier; on the beach just above high water, about 24 meters from edge of vegetation, between the sandhills and the sea. The point was roughly marked subsequently by a post 4 by 4 meters by 8 feet (12 by 12 cm. by 2.4 meters). The lighthouse is in true bearing 323.15 meters. NORTH AMERICA. United States. Baldwin, Kansas, 1905, 1906. — Observations were made at the absolute magnetic observatory of the United States Coast and Geodetic Survey. The true bearing of flagpole on Science Hall is 131' 39'4. At the end of 1906, a secondary station, designated as tent, was occupied at a point about 50 feet (15 meters) from the absolute observatory, in line with flagpole on Science Hall of Baker University. Berkeley, California, 1905.— The station of the U.S. Coast and Geodetic Survey of 1904, on the grounds of the University of California, was reoccupied. It is west of and in line with the north face of South Hall, 261.5 feet (79.7 meters) from its northwest corner, 31 feet (9.4 meters) west of center of path leading from gymnasium to North Hall, 46 feet (14.0 meters) north of the path leading from South Hall to Center Street entrance to the grounds, and 54 feet (16.5 meters) from edge of driveway: marked by a granite post 8 by 8 by 24 inches (20 by 20 by 60 cm.) set flush with ground and lettered U. S. C. & G. S. The Coast and Geodetic Survey station of 1904. It is on a military reservation of the United States Government near the center of the plateau just west of the hill at the extreme eastern end of the island, is nearly in line with the top of the hill and the smokestack at the naval training station, and about 50 feet (15 meters) north of the line of the wireless mast on the highest part of the island, and the flagpole on the south side. United States — continued, The site of the town in front of the office building; marked by many sides in top of a room stone by 6 by 12 inches (15 by 15 by 30 em.) with a short top which projects slightly above the general surface. In 1908, three secondary stations were established. The first is 74 feet (22 meters) true north 56° 06' east of the main station. The second and third, used for ship instruments, were about 45 feet (14 meters) west of and 35 feet (11 meters) northwest of the main station, respectively. (Main station reoccupied in 1916.) Kutkan Idoml. AUuka, 1907.— On the eastern coast of land on Kutkan Island, 30 feet (9 meters) from the water's edge, at high tide, on the north side, 12 feet (4 meters) on the south side, and 50 feet (15 meters) from extreme eastern edge of island. A cross, cut in the top of a Large irregular rock projecting about a foot above ground, must be the exact spot. The following true bearings were determined: pier at Sitka absolute magnetic observatory, 156.49; U. S. Marine Corps barracks flagstaff, 148.51; Mission flagstaff, 187.33; San Diego, 1905, 1906. — Five stations were established here: these are designated as San Diego, Secondary, IL and C. A. O. S., 1864. The first San Diego is near the northern point of North Cofonado Beach Island; near the shore of the bay, facing the city, about 320 paces west of the west corner of engine house of Marine Railway (Speckels) and 58 paces from road that runs along the beach. Beacon No. 10 bears approximately north-northwest from the station, which is marked by a spruce post, 6 by 6 by 50 inches (15 by 15 by 127 cm.) set with its faces approximately with the cardinal points and projecting about 1 foot (30 cm.) above the surface; the letters C. I. are cut on the north face and 1905 on the south face. The following true bearings were determined: School of Theosophy, 96.47; stand pipe, 187.54; flagpole on south tower of Coronado Hotel, 338.38. A second station, designated as secondary, was established 50 feet (15.2 meters) south-southeastward in the line toward the Coronado. ado Hotel from San Dietm /. San Diero // is on the northwest portion of North Coronado Beach Island, about midway between the C. ft G. S. station at Quarantine and Station I; about 75 yards (69 meters) from the northwest beach of North Coronado Beach Island, and in the line joining Harbor Beacon No. 2 and the south end of the most southerly building on Quarantine Wharf; marked by a redwood post 4 by 6 by 44 inches (10 by 15 by 112 cm.) projecting about 8 inches (20 cm.) above ground. The letters C.I. and the numeral II are cut on the two faces which face the north and south respectively. The following true bearings were determined: south tower of Coronado Hotel, 306° 40' 8; old lighthouse, Point Loma, 33° 37' 7; central dome, School of Theosophy, 117° 28; 1. San Diego // is on the north shore of San Diego Bay, on a low beach northwest of Dutch Flat, and about 100 yards (91 meters) north 25' east of a triangular signal on The sand spit marked by redwood post 4 by 6 by 52 inches (10 by 15 by 132 cm.) extending about 10 inches (25 cm.) above ground and having the letters C. I. cut in the north face, and a hole near the center of the top. The following true bearings were determined: southern tower of Coronado Hotel, 337. 1897; old lighthouse, Point Loma, 24.08; School of Theosophy, 63.28. The C. & G. S. 1897 station, occupied in 1905, is that established by the Coast and Geodetic Survey in 1897. It is in the northeast portion of the city, about 150 feet (46 meters) southwest of where Seventh and Fir streets would intersect if extended. In the park, marked by redwood post 4 by 4 by 36 inches (10 by 10 by 91 em.) post off the ground, lettered U. S. MAG. and 1807 on its north and west vertical faces respectively. San Francisco, Prudio, Calcurnia, 1906.— The station of the U. S. Coast and Geodetic Survey of 1904, at the triangulation station on Presidio Bm, northwest of the gate on the south side of Presidio grounds at the edge of the woods, was reoccupied; marked by stone post 6 inches (15 cm.) square on top, projecting 6 inches (15 cm.) above ground and levered on top U. S. C. A G. Stvvey, 1881. The following true beginning have been determined; cross on Lone Mountam, 32½ 53½; center of top of Drake Cross, 27½ 03:7. [This station reported in 1916 as no longer suitable. A 6 million gallon reservoir is now on the site.] San Rafad, California, 1905, 1906.— There are three stations, two being those of the U. S. Coast and Geodetic Survey of 1897. They are 1.1 miles (1.8 kilometers) northwestward from the county courthouse, on the eastern side and near the top of a hill, about 375 feet (115 meters) distant from one of the water company's reservoirs. There is a meridian line marked by two marline posts 8 by 8 by 48 inches (20 by 20 by 122 cm.) projecting about 24 inches (61 cm.) above the surface of the ground; the north stone is lettered U. S. C. ft G. S. on its west vertical face, MAG. STA. on the south face, and 18 On the east face, and bears a cross on its upper face making the exact point. The south stone is set about 2,300 feet (701 meters) due south of the station, its north vertical face being lettered. MER. BARK, the east face U. S. C. & G. S., and the west face 1897. In 1897, 1905, and 1906, dip-dride observations were made at a point, designated as Divisional Survey 50 feet (15 meters) from the north stone, and magnetometer observations were made at a point, designated as Magndomder Station, 10 feet (3.0 meters) from the north stone in the extension of the line from flagstaff on the courthouse to the north stone. In 1908, observations were also made over the north pier. The flagpole on county courthouse is in true bearing 289.46. Sitka, Alaska, 1907. — Two stations occupied: the principal pier in the Sitka auxiliary magnetic observatory of the Coast and Geodetic Survey, and in the regular absolute house. SOUTH AMERICA. Peru. San Lorenzo Island (Calma Harbor), Lima, 1906. — The main station is about 5.5 feet (1.7 meters) above and about 50 feet (15 meters) distant from the ordinary high-water mark on the beach, and is approximately the U. S. Coast and Geodetic Survey station of 1907. It is 79 feet (24.1 meters) and 67.4 feet (20.54 meters) from the northeast and southeast corners of the powder may line (marked "Deposito de exploivoe") of which are in true bearing north 68.7 west and south 34.1 west respectively, and 57.5 feet (17.5 meters) from door of masonry directly beneath the flagstaff. The point is marked "square tower" with door in. Cala, 250. 31.0; spire of church on point in Callao, 256.00. A secondary station designated as San Lorenzo Island B was established at a point south 31.5 feet (16.0 meters) distant from main station. Descriptions of Shore Stations, 1905-08 ISLANDS, PACIFIC OCEAN. CAOLDI ISLAND ISLAND. From the beginning, the main station is on the northwesterly portion of the island, near the end of Toml Bay, in Port Toml Bay, about 100 feet (30.5 meters) from the west and about 500 feet (152 meters) from the northwesterly shore lines of the island, and 55 feet (10.8 meters) northwest of a lane tree. Marked by a pine post 5 by 5, by 40 inches (12 by 14 inches) set so as to project about 16 inches (40 cm.) above vertical surface; the lower part of post is tarred and the upper part painted white, with C. I. marked on one side and 1907 on the opposite side; the precise point is indicated by a cross cut in the head of a brass wire set in the center of the post. The following true bearings were determined: beacon on Buray Hill, 88.88; chimney on west gable of long white cable building, 80.05. Two secondary stations were established, designated as Yap, Yap, and Yap, the 8th 80.8 feet (12.08 meters) west of the main station, and the second 40.1 feet (12.23 meters) east of the main station; both secondary stations are in range with the principal station and the harbor beacon. From Yap, B, the windmill at cable station is in true bearing 44.37. Fanning ISLAMN. , /aknd, 1006, 1006.— The main station is on a moaf plain east of cable station and near shore of lagoon, 100 feet west of rear of boat house on shore of lagoon and in line with quarters building at cable station. Bided by a redwood post 4 by 4 meters (10 by 10 meters) in cross section and 40 inches (102 inches) in length, set so as to project about 1 foot above general surface; small hole in top of post marks the predominating point. The following true bewing were determined: flagstaff at cable station, 1006. W. W. W. rod of windmill, 1006. A secondary station was established in 1906 at a point about 100 feet (80 meters) true north 55° 52' west of the main station. Fui Islands. Fum, Via Lmu Idand, 1006.— About 2 miles (3 kilometers) from Swn, on north shore of Suva Harbor and on a point called Suva VoU, identical with H. M. S. Ifatefwildk station of 1806 and was found marked by a concrete post standing about 18 inches (45 cm.) out of ground. The poet is marked with an arrow and the year 1896. The lower lighthouse is in true bearing 129. 48.6. A secondary station for dips observations, and designated as Suva You B, was established about 75 feet (23 meters) northeast of above station. Hawaiian Islands. 8th (Hawaiian Magnetic Observatory), Oahu Island, 1905, 1907. — The observations were made on the magnetometer pier of the absolute house of the Coast and Geodetic Survey magnetic observatory, located at Sia. In 1907 a tent station. A, was also occupied about 40 feet (12 meters) due true north of the abeo-kite observatory pier, in the observatory inclosure. A ssoond tent station, B, was established about 60 feet (18 meters) southwest of the absolute observatory, in observatory indosure. The various ship instru- ments were tested in 1907 at several other points in the observatory grounds. Mauanas. ^ 1906.— Four stations were established, two at Oiote Foint and two at Cabras Island. The main station at Orote IViint is east of the Point, on the ■oath ads of Apra Harbor, and on a sand beach near ISLANDS. PACIFIC (XJEAN. Mauanas— eofiehidad. of hi|^ land on outer edge of vegetation. Marked bv a cement post,rfiet with its top somewhat above surface of ground. The following true bearingi were determined: flagpole at Piti, 256* 39:i; wireless tdesraph pole, 266* 03'6. Observations were also mack at a point, designated Orote Seeondary, about 30 feet (9 meters) east-northeast of the main station. The main station on Cabras Idand is on the north side of Apra harbor, approximately 150 yards (140 meters) west of coal shed and about 30 feet (9 meters) from water. The following true bearingi were determined: flagpole at cable station, 41* 09:4; magnetic station at Orote Point, 71* 07:0. Obser- vations were also made at a point, designated Cabras Seamdary, about 50 feet (15 meters) west of principal station. MABQXTxaAS Islands. Nukahwa Itkmd, 1907. — A number of stations were occupied and indicated local disturbance. Station 8 is on the site of the old Fort Collet, a small, conspicuous rodsey knoll on east side of Tai-o-hae, or Anna Maria Bay, and about 90 feet (27.5 meters) above sea-level. The point is about 40 feet (12 meters) northwest of a trail which leads up from the public land to the harbor light, which is fixed to a pole 57.8 feet (17.63 meters) distant. Marked by a hole in the tap of a pine post 3.5 by 5.5 by 33 inches (10 by 14 by 84 cm.) set one-half its length in the ground. The harbor light is in true beanning (T 40° west of south. Station 9 m near the northwest head of Tai-o-hae, or Anna Maria Bay, on land covered with a dense growth of tall brush, belonging to the government. This point is 27 feet (8.2 meters) distant. and about 3 feet (1 meter) above high-water mark. The station is marked by a hole in top of a pine post 3.5 by 3.5 by 44 inches (9 by 9 by 110 cm.) projecting about 40 cm. above the ground. Three test stations were also established at points around 9; they are designated as Pi, 9%, and Pf. The following true bearings were determined from 9: station 8, 278. 42:37 harbor light pole, 279. 07.6; northwest edge of (government House, 274. 00. 4. Two additional stations were placed on the line determined by station 8 and the basaltic diff. which is in true bearing 60. 29.1 west of south from 8. The first, desipiated as ^i, is 40 feet (12.2 meten) west, and the second, ^, is 43 feet (18.1 meters) east along this line from the principal station. Mabshall Islands. JaluU Island, 1906, 1907.— The main sUtion of 1906 and 1907 is at American Town, about one and one-fourth miles (2 kilometers) south of the settlement, near the high-water mark and the shore end of the old railroad pier. Marked by a cement post bearing the letters C.I. 1906, set wiUi its top slightly above the surface of the ground. The following true bearings were determined: Company's flagpole. 204* 17 ;2; hotel fla^rtair, lOr 38:4; beacon in lagooDi 183* 31 !8. Observations wore also made in 1906 at a point, designated as Jaluit Seccmdaty, about 30 feet (9 meters) to the south and in range with station and Omipany's flagpole. Station Jaluit /// of 1906 was establislMd to test k>cal disturbance about the position of swing in harbor, and is about 8 miles (5 kilometers) southwest of the principal station. I)ip observations were made at a point, /// Secondary ^ about 75 feet (22.9 meters) east of ///. In 1907 a secondary station, designated Jaluit Seetmiory f , was established at a point 57.8 feet (17.62 meten) tma south XT W west of the mam station. 114 OcBAN Magnetic QBSXRVATioNSy 190&-16 ISLANDS, PACIFIC OCEAN. Samoan Iblamdb. Apia, UpcHu J9Umd,l906, 1906, 1007.— The obMnrations nuMie by O. Heimorod in 1906 w«re at the fint •beolute house. <m the spit of hoid eaUed Mulmum. of the Samoa Obeervatoiy of the Iniporiftl Academy Of Soieooea of QMtmgen. The obaervatioiia of 1906 by the offioera of th»QaUU$were nuMle at three pointa. Of these was the first absolute house of the Samoa Observatory. The second station, designated North Pier, was in the observatory grounds about 50 feet (15 meters) north of the absolute house. The third station, designated as Bail Pier, was in the observatory grounds about 50 feet (15 meters) east of the absolute house. The observations in 1907 were made at two stations. The first, designated Sump, was near the north pier station of 1906, being about 10 feet (3 meters) northwest of the north pier. The second, designated as Weel Pier, was in the observatory grounds about 41 feet (12.5 meters) west from west wall of the new absolute house. The first absolute house of the observatory was being rebuilt at the time of the 1907 work and it was not possible to observe in it. SocnTT ISLAMDS. Mali Via. Tahiti Island, 1907.— Three stations were occupied near southeast corner of Sudl island called Motu. Uta in Ptoeete Harbor and designated as Motu Uta. Motu Uta 1, and Motu Uta 1. Ware in line with flMstaff at Government Building. Motu Uta is the middle point, and stations 1 and 3 are 30. feet (9.1 meters) on each side, being near the high water mark. The dam bearing of cathedral spire from Motu Uta, 296. 59:0. Station Motu Uta was used only as a test station for local distance, and an observations were incomplete and for that reason no results were given. Papeete, Takill Island, 1907.— Within and near eastern corner of a tract of government land immediately south of the Botanical Garden, approximately 350 feet (106 meters) southeast of gardener's house in Botanical Garden, 175 feet (52 meters) northeast from windmill pump on government tract, 73 feet (22.2 meters) south-southeast from a long coconut tree standing near the fence, and approximately 50 feet (15 meters) from the fence to east and south. Marked by a hardwood post, lettered on top T. M. C. I. and having a copper tack at the center. A secondary station was occupied 50 feet (15 meters) True north 32° 32' west of the main station. Smaa Carol Idand (Papeete Harbor), Tokyo Island, 1907.— On a small sandbar, about 100 feet (30 meters) long, and the same in width, rising about a foot (30 em.) above high water, situated south of entrance to Capeete Harbor. Marked by a fir post about 31 inches (9 cm.) square and 4 feet (1.2 meters) long, sunk 1 foot (30 cm.) in the ground. The following true bearings were determined: Cathedral MSS,  letters to those in command of the vessel will serve to explain the routes followed by the vessel and the methods of observation adopted for the various kinds of work. While some of the early methods, according to experience gained, were modified or superseded, their complete presentation here will be useful in showing how the observations were made at the successive stages of the work, and how the methods and instruments were gradually developed and improved. The comparison of instructions for observations aboard a magnetic ship with those for the work on a non-magnetic one (see pp. 316-324), will be of interest, and will show the great superiority of having a vessel specially adapted for the problem undertaken. The extracts form thus also an historical record of the experiences it was necessary to pass through before reaching the goal set. When referring to "swings" of vessel, the term "first helm" is used, regardless whether vessel was swung first with starboard or with port helm. The term "other helm" signifies that the vessel was swung next with helm opposite to that used first. Thus, if for any series of swings, "first helm" is the starboard helm then "other helm" is the port-helm swing. CRUISE OF THE GAULEE. 1905. J. F. Pratt & Co. From Instructions on Aug. 15, 1905, to J. F. Pratt, San Diego, Cal. Upon completion of the necessary alterations on the Oahuel, you will proceed with her to Honolulu, Hawaii, thence work northward as far as the conditions will permit, returning once more to the Hawaiian Islands, if considered best, thence to the Midway Islands, and return to San Francisco about December 1, 1905. (This is a general outline of the region to be covered, the present manner of execution for the successful conduct of the work being left to your judgment.) The necessary swings for the determination of the deviations in the declination, dip, and intensity will, of course, again be made at the time of departure from San Diego. (For the harbor swings, whenever possible, 16 equidistant headings should be taken.) It is especially essential that, during these swings, all articles likely to affect the instruments be in same position as at sea. In this connection, you are urged to pay special attention to the iron at the head of the sail when down on the boom, in which position it may Come too close to the dip-circle position. In general, the same methods are to be pursued as at San Francisco, except that observations with sea deflectors are to be made as follows: First 8 points use magnet 45, letters on magnet up, next 8 points use magnet 45, letters down; for swing on other helm, use magnet NL, letters up, on 8 points, and then on remaining 8 points, letters down. As much time as possible should be given on each heading, and the list, roll, and any other pertinent data be noted. If not already done, deflection observations should be made ashore with magnets 45 and NL (letters up and down), so as to determine the constants anew. Likewise, the times of oscillation of the two Kelvin cards, as at San Francisco, are to be obtained. Chained to San Diego. Chained to San Diego, having proved this number sufficient for the Columbia. All observations made at San Diego, inclusive of the ship swings, are to be transmitted to Washington, so that the Office can make final reduction of the work done on the trip from San Francisco to San Diego. Abstracts of the essential quantities should be made in the "Abstraet Books" left in your possession. In general at sea, swings on as many points as possible are to be secured, on the average every second or third day, conditions. Pending, and observations be made on the intermediate days on the ship's course, again using every precaution as to the position of armaments likely to affect the instruments. In the sea-deflector work, it is preferable to use each time both magnets as per general scheme above, not having, however, on the bridge more than one magnet at a time. On the course observations. — Dip and intensity observations with sea dip-circle 169 (needles 1, 2, S, 4) and observations with sea d'ector 1 should be made according to method followed on experimental trip from San Francisco. It will be well to interchange observers. Thus first day: Dr. Egbert, sea deflector; Mr. Ault, sea dip-circle. Next day: Dr. Egbert, dip circle; Mr. Ault, deflector, etc. The endeavor should be to have the mean time of the deflector work about the same as that for the dip circle. Should it not be possible to make deflections with the dip circle in low latitudes, then continue, nevertheless, the observation with the loaded needle, and then secure relative total intensity. The observers must be cautioned to take every possible care in handling the needles. Should anything happen to needle No. 3, preventing its further use, then cable as soon as possible and substitute for it one of the dip needles (No. 1 or 2), noting that there After the particular dip needle selected can no longer be used for inclination observations, and must not have its magnetism disturbed; it should be kept in the box with No. 4. In case anything happens to the loaded needle (No. 4) so as to make impossible observations with it, then continue simply the deflections and inform the Office promptly of the accident. It is sincerely hoped, however, that these contingencies will not occur. Owing to the difficulty in securing declinations, on account of meteorological conditions, it will be necessary to avail yourself of every opportunity to secure data, keeping a man on the lookout on the bridge whenever necessary. The observations should be made over as long an interval as possible, and it will suffice to get them, in general, with the Ritchie standard compass (RIA); however, it will not be amiss to secure comparative data with the other compasses, this being one of the purposes of the expedition. The list, roll, and all other pertinent data must be entered in the record for all observations made. The general investigation of local disturbances in the vicinity of land-masses must be left to your judgment, this matter being dependent on conditions encountered. The various instrumental constants and ship deviation-coefficients will again be determined at Honolulu, Hawaii, making use of the facilities at the Coast and Geodetic Survey Magnetic Observatory, so as to check up once more on the instruments. They will also be determined. Again, at San Francisco, all navigational data and geographic positions assigned to the observations at sea must be checked by some independent observer, besides the one to whom you will give chief charge of this work. From Directions of September 18, 1905, to J. F. Pratt, Honolulu. 1. Judging from experience in the discussion of observations made on Coast and Geodetic Survey vessels, and that now being encountered on the Galilee, it would appear that our principal trouble on the latter vessel will arise from the shifting positions of masses of iron, as for example, hoisting chains and blocks. There are several instances in our observations from San Francisco to San Diego where differences have occurred, which can only be explained by the circumstance that masses of iron may have come too close to the instruments. 2. You are therefore requested to make a study of the remaining masses of iron in the rigging, sails, and hoisting tackle, which could be replaced by non-magnetic metal, and to make an estimate of the probable cost, so that it may be decided whether the changes can be made when the Galilee returns to San Francisco (San Diego). A critical analysis of the observations thus far shows very clearly that if we can properly control the positions of the remaining masses of iron, a most gratifying change is likely to follow. Instructions for the Galilee Work Degroes of accuracy in the determination of the magnetic elements may be obtained. Certain observations on August 7 show very clearly that, between the inclination and the intensity observations, something occurred which caused a different distribution of iron masses within the region of influence. It is also extremely essential that the observer remove from his person all articles likely to affect the instruments, and it would be well to devise some form of statement to be entered in the report of the observations to insure that this has been done. From Directions of October 16, 1905, to J. F. Pritt, Honolulu. On the 12th instant, the following cablegram was sent to Honolulu: "Daily swings necessary. Instrumental changes require closing San Diego instead San Francisco. Instead failing, observe usual dips. Aclmowledge." We are having great difficulty, for one reason or another, making the deviations fit theory, and it is believed that the only safe course to follow is to string every day, so that the mean results will be free from uncertainty on account of deviation. It will be a great saving, especially in the computation, if we do not have to bother with deviations. With this experience in mind, please do your utmost to secure swing as often as possible. You will doubtless swing the Galilee off the coast near the Honolulu Magnetic Observatory, about where you swung the Patterson, of the Coast and Geodetic Survey, in 1904. The cablegram calls for dip observations in place of the deflections when they fail. From Directions of October 17, 1905, To J. F. PRIEL, Honolulu. Before it is possible to reduce completely the observations from San Diego to Honolulu, it will be necessary to secure some good swings at Honolulu at the place mentioned in the letter of yesterday. At least two good swings are desired: for example, one a.m. and one p.m., to be repeated, if observations are not satisfactory. The inclination and intensity observations should be made thus: a.m., observations with loaded needle on first helm, next inclination observations with needle No. 1, say on the other helm swing; p.m., observations with loaded needle on helm opposite that of the morning; next inclination observations with needle No. 1 (polarities reversed) on other helm. It would be preferable if observations could be made on each heading for each of the positions of the middle Coast for the loaded needle and the dip needle. Thus, the observations on each heading would be for the positions: face circle east; face needle east; face circle west; face needle west; etc. Swings with dip needle and loaded needle should be kept up after leaving Honolulu until the defect is made, after which it will be desirable to handle; for example, on one day swings with loaded needle and with dip needle, while on the next day, swings will be made with the loaded needle, followed by deflections. At San Diego, the port of arrival, swings will be made, using both methods given in 2. Inclination observations at the land station should hereafter be made regularly by the direct method, also with needle 3, not reversing polarities, however, in the latter case. It will therefore be necessary, before you leave Honolulu, to make such observations at the Honolulu Observatory in sufficient number to give a good value of the correction required to reduce the indication thus obtained with No. 3 to the standard value. Whenever the deflection method is applicable, the inclination will likewise be obtained in this way, in order that the data may be derived for determining the corrections on account of non-reversal of polarity of deflected. From Instructions of November 22, 1905, to J. F. Pratt, San Diego, Cal. In addition to the directions contained in the instructions of August 15, and letters of September 18 and October 16 and 17, respecting the closing work at San Diego, complete magnetic observations (D, Jf, /) at both C. I. W. shore stations Nos. I and III, between which the ship was Swung last August, are to be made. At both of these stations, furthermore, standardization observations will be made with the dip circles, and the intensity constants will be determined for the sea deflector, and for the sea deflector. Equation to meteorology conditions considered, this did not prove feasible. All observations called for in paragraph 1 will be computed and revised immediately, and repeated, if necessary, before any change whatsoever is made in the ship or in the instruments. For your guidance, there is enclosed a tabulation of the previous results obtained. Please note that the swings at San Diego must be made under the same conditions of ship as at sea, as nearly as that can be attained, and that the same methods, e. 9., for amnuth, be used as for the sea observations; otherwise, the deviations obtained will not strictly apply. A complete tabulation of the corrections for all time-pieces on board must be forwarded to the Office, so that their behavior will be known. It would be extremely desirable, in order to improve the sea dqHdrde and obviate the deflection method failing so quickly, that a rough determination be made of the distance at which deflections would be possible at the Honolulu Observatory. If you have not covered the gimbal stand for the dip drde so as to shield the pendulum bob from the wind, please attend to. This. Some of the outstanding effects on the dip circle apparently cannot be ascribed to ship deviations, but rather to a want of level of the instrument, as might be caused, for example, by the action of the wind. The complete analysis of the entire work also makes it desirable that the deviations for a compass placed at the dip-circle position be determined at one of your ports. This can be done by comparison, using, for example, the method followed with reference to the Kelvin compass at San Francisco. Please request the observers to make a note on the dip sheet when they remagnetise the dip needle before beginning the observations, and to give the number of strokes used. From Instructions of December 18, 1905, to J. F. Pratt, San Diego, Cal. Before leaving San Diego, please make sure that all instructions sent to you respecting the closing work at San Diego have been fully carried out, in order that there may be no difficulty in the final reduction of the observations. This is especially important in view of the contemplated changes. You will of course see to it that all reports and records are complete, as called for in the various instructions before forwarding them to the office. You will arrange, as offered, regarding the early completion of the additional alterations agreed upon, which, briefly stated, involve: (a) building a new galley over the fore hatch; (b) cutting off the after end of the old house, so as to leave about 8 feet for a forecastle; (c) extending the observatory bridge; (d) changes in hoisting-gear so as to make it as non-magnetic as possible; (f) removal of iron strips around middle hatch; (f) building of an extra cabin. (If binnacles and stands on the bridge are removed, their present places should be carefully marked, so that, if necessary, everything can be exactly replaced.) Since it has been arranged that the alterations will be supervised by Captain Hayes, who will also be responsible for the property on board the ship, Mr. Ault may be authorized to proceed to the Baldwin Magnetic Observatory for the detennination of the desired instrumental constants. CRUISE II OF THE GALILEE, 1906. W. J. Phelps in Coincidence. From General Instructions of January 9, 1906, to W. J. Peters, Washington, D.C. As soon as convenient, you will proceed to San Diego, California, via San Francisco, assume charge of the yacht Galilee, engaged in the magnetic survey of the North Pacific Ocean. At San Francisco, you will confer with Captain J. F. Pratt, at the suboffice of the Coast and Geodetic Survey, regarding the duties assigned you. Respecting the alterations now being made on the Galilee, and their status, you will be advised by Captain Pratt, whereupon you will relieve him of the supervision, and attend to such payments as he may advise you. You have already been informed that the chief cause of the compass deviations is located on the port side of the bridge and forward of the positions of the compass, about in the direction of the port side of the old galley. It is quite possible that some effect may also come from the iron material in the boat on the port side. You will make the desired corrections. From Routt Insurances on Jan. 20, 1906, to W. J. Pberts, San Diego, Cal. 