A PRELIMINARY REPORT ON REQUIREMENTS FOR A VESSEL SUITABLE FOR INVESTIGATIONS 

 IN MAGNETISM, ELECTRICITY, AND OCEANOGRAPHY 



The following report is submitted by the committee 

 consisting of Messrs. Peters, Soule, and Torreson, ap- 

 pointed by Dr. Fleming to make a study of ways in which 

 the Carnegie Institution might be helpful in the develop- 

 ment of a plan for construction of a ship primarily for 

 oceanographic researches but also for occasional mag- 

 netic and electric observations. 



This report reviews certain general requirements 

 that should govern the selection of the type of vessel. 

 Various suggestions for improvement in instruments and 

 equipment, in the operations, and in the scope of the in- 

 vestigations, based on experience on the Carnegie , will 

 be the subjects of other reports. 



The requirements in the construction and in the 

 method of propulsion, especially in the maneuvering of 

 the ship for trawling and for securing bottom and deep- 

 sea samples, are quite at variance with the require- 

 ments for the precision sought in magnetic observations. 

 For one, the essential is power for executing the vari- 

 ous operations of the investigations and power to maneu- 

 ver the ship during these operations; for the other, free- 

 dom from effects of iron masses is the most essential, 

 economy in supplying power being more desirable than 

 facility of maneuvering. 



Other investigations at sea in general do not demand 

 such very contradictory requirements. Atmospheric- 

 electric observations, gravity determinations, pilot- 

 balloon observations, and other meteorological observa- 

 tions can be made with equal facility on any vessel of 

 the same approximate dimensions regardless of the gen- 

 eral construction and propulsion. There are, however, 

 details in construction and propulsion that should not be 

 overlooked. For example, atmospheric-electric opera- 

 tions require installation to windward of gas and smoke 

 exhausts, temperature gradients of the atmosphere re- 

 quire lofty installations, gravity determinations require 

 freedom from engine vibrations- -all of which could be 

 provided for on a steamer if they were considered well 

 in advance of construction or alterations. Convenience 

 in the collection of water samples in any sort of weather 

 and ready accessibility to ample storage space may also 

 require attention to details in construction in any type of 

 vessel. 



For securing oceanographic deep-sea and bottom 

 samples a twin-screw vessel driven by steam, gas, or 

 electricity is preferable to a sailing vessel. The loss of 

 sounding wire with its expensive collection of bottles, ther- 

 mometers, and snappers might be averted on occasions if 

 the ship could be maneuvered more easily and quickly than 

 could the Carnegie . A larger vessel would also be more 

 steady, and thus might facilitate the operations, but the 

 maneuvering of a very much larger vessel would be 

 slower. Twin screws, however, imply a steel hull in 

 usual construction, which also has advantages in the 

 greater space it provides and possibly in more economi- 

 cal upkeep and in the installation of subsurface acoustic 

 apparatus. In building a special twin-screw vessel, or 

 even more in the purchase of one ready built, one should 

 beware of in-turning screws, which practically destroy 

 the maneuvering power of twin screws (1). Masts and 



sail, even if only as auxiliary on a steamer, might be 

 useful in maneuvering at sea during deep-sea work; also 

 in keeping course with engines stopped in gravity work 

 and affording lofty positions for meteorological work. 

 Other power than steam might be considered with advan- 

 tage, as the diesel-electric drive on the U. S. Coast and 

 Geodetic Survey Hvdrographer. 



A steel hull, however, is fatal to the precision re- 

 quired in magnetic observations. For example, the iron- 

 built Clyde and the Citv of Sydney of the British Mercan- 

 tile Marine had deviations of which the constant part 

 during a swing amounted to Of 7 and l.°4 in declination, 

 10° or 11° in inclination (British Channel) and about 25 

 per cent of horizontal intenr-ity in the determination of 

 this element (2). The values of the constant part of the 

 deviation during a swing are difficult to control, since 

 they must be determined from swings surrounded by 

 land stations. Such swings must be made in many ports 

 where the dip and intensity are quite different and even 

 then they are not always satisfactory. 



The advantage of nonmagnetic construction is the 

 elimination of long and often unsatisfactory computations 

 of the deviation corrections, thereby permitting: (1) fa- 

 cility in securing a dense distribution of observations 

 over the seas for the improvement of navigational charts 

 and for use in theoretical investigations of the earth's 

 magnetism; (2) rapid determinations of secular change 

 far from land; (3) detailed surveys of ocean areas known 

 to be or suspected of being locally disturbed; (4) exper- 

 imental work at sea for the improvement in magnetic in- 

 instruments otherwise not possible because deviations 

 might obscure the results of experiment. In view of the 

 work already done on the Carnegie , the work described 

 in (1) may be regarded as accomplished. The most 

 suitable vessel for (2), (3), and (4) would be a schooner 

 constructed to a large extent, though not necessarily 

 entirely, of nonmagnetic material. Schooners are 

 manned by less than half the crew of the Carnegie , and 

 the cost and upkeep of masts, spars, rigging, and sails 

 would be reduced correspondingly. Auxiliary power 

 would be needed only occasionally. A vessel fitting these 

 specifications, with small alterations, might be found for 

 sale at an insignificant sum (3). Such a vessel, however, 

 would not serve for deep-sea sounding work, although 

 she would be suitable or adaptable for other oceanic in- 

 vestigations besides magnetic. 



For both magnetic and deep-sea oceanographic work 

 the best practical compromise appears to be a vessel as 

 large as or even somewhat larger than the Carnegie , 

 with sails in addition to steam or some other dependable 

 power for propulsion. The construction would be wood 

 as far as practical. It might be noted here that for ice 

 navigation, wooden construction suitably reinforced gen- 

 erally has been preferred to steel. Wooden construction 

 also would be less objectionable in radio experimental 

 work. A location for magnetic instruments should be 

 selected after a preliminary plan had been drawn or a 

 survey made showing the location of engine, chain lock- 

 ers, tanks, and other large masses of iron, and magnetic 

 material should be excluded within a space of eight 



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