118 Ocean Magnetic Observations, 1905-16 



2. All obsei-vations 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 inclosed a tabulation of the previous results obtained. * * ♦ 



3. 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. g., for azimuth, be used as for 

 the sea observations; otherwise, the deviations obtained will not strictly apply. * * * 



4. A complete tabulation of the corrections for all time-pieces on board must be forwarded to the 

 OfBce, so that their behavior will be known. * * * 



5. It would be extremely desirable, in order to improve the sea dip-circle and obviate the 

 deflection method faiUng so quickly, that a rough determination be made of the distance at which 

 deflections would be possible at the Honolulu Observatory. 



6. If you have not covered the gimbal stand for the dip circle so as to shield the pendulum bob 

 from the wind, please attend to this. Some of the outstanding effects on the dip circle apparently 

 can not 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. 



7. 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. 



8. Please request the observers to make a note on the dip sheet when they remagnetize 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. 



1. Before leaving San Diego, please make sure that all instructions sent 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. 



2. 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. 



3. 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 forehatch ; (b) cutting 

 off the after end of the old house, so as to leave about 8 feet for a forecastle; (c) extending the ob-serying 

 bridge; (d) changes in hoisting-gear so as to make it as non-magnetic as possible; (e) removal of iron 

 strips around middle hatch; (/) 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.) * * * 



4. 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 Observatoiy for the detennination of the desired instrumental constants. * * * 



CRUISE II OF THE GALILEE. 1906. 



W. J. Peters in Command. 

 From General Instructions of January 9, 1906, to W. J. Peters, Washington, D. C. 



1. As soon as convenient, you will proceed to San Diego, California, via San Francisco, and 

 assume charge of the yacht Galilee, engaged in the magnetic survey of the North Pacific Ocean. 



2. 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. * * * 



3. Respecting the alterations now being made on the Galilee, and their status, you will be ad- 

 vised by Captain Pratt, whereupon you will relieve him of the supervision, and attend to such 

 payments as he may advise you of. You have already been infonned that the chief cause of the 

 compass deviations is located on the port side of the bridge and forward of the positions of the 

 compasses, 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 



'See aUo paragraph 32 of J. F. Pratt's report, p. 133. 



