February 23, 1905J 



NATURE 



389 



by the excellence of Dr. Findlay's translation. The 

 present edition is practically a reprint of the first, 

 except in so far as a few pages have been added on 

 radio-active phenomena, in connection with the rnetals 

 thorium and uranium ; a necessarily short description 

 is given of compounds of radium, and a sketch of the 

 transiormations undergone by that curious element in 

 arriving at a stable condition. W. R. 



LETTERS TO THE EDITOR. 



[The Editor does not hold himself responsible for opinions 

 expressed by hts correspondents. Neither can he undertake 

 to return, or to correspond with the writers of, .ejected 

 manuscripts intended for this or any other part of Nature. 

 No notice is taken of anonymous commumcations.\ 



A Contemplated Magnetic Survey of the Norih Pacific 

 uceaii by the Carnegie Instituiion. 

 A PROJECT for a magnetic survey of the North Pacific 

 Ocean by the Department of International Research in 

 Terrestrial Magnetism has been favourably acted upon by 

 the executive committee of the Carnegie Institution of 

 Washington, and authorisation has been given to begin 

 the work this year. An initial allotment of 20,000 dollars 

 has been made to cover the expenses for the current year. 



As is well known, the state of our knowledge of the 

 distribution of the magnetic forces over the greater portion 

 of the earth — the oceanic areas — owing to the paucity of 

 precise data, is exceedingly unsatisfactory. This fact is 

 especially true for that great body of water the Pacific 

 Ocean, rapidly developing in great commercial importance. 

 Captain Creak, for many years superintendent of the 

 Compass Department of the British Admiralty, now retired, 

 says : — " The North Pacific Ocean is, with the exception of 

 the voyage of the Challenger, nearly a blank as regards 

 magnetic observations, and I therefore think the Magnetic 

 Survey proposed will be of great value." 



Hence, except for data from occasional expeditions and 

 such as were acquired in wooden vessels a long time ago, 

 the present magnetic charts used by the navigator over this 

 region depend largely upon the observations on islands 

 and along the coasts. Such land observations, however, 

 are rarely representative of the true values because of 

 prevalent local disturbances. It is, therefore, impossible to 

 make anv statement as to the correctness of the present 

 charts. The demands of science, as well as those of com- 

 merce and navigation, require a systematic magnetic survey 

 of this region under the most favourable conditions possible, 

 and that the work be done under the auspices of some 

 recognised research institution in order to ensure that the 

 scientific aspects of the work receive their adequate recog- 

 nition. 



The eminent physicist and magnetician Prof. Arthur 

 Schuster states as his opinion : — " I believe that no material 

 progress of terrestrial magnetism is possible until the mag- 

 netic constants of the great ocean basins, especially the 

 Pacific, have been determined more accurately than they 

 are at present. There is reason to believe that these con- 

 stants may be affected by considerable systematic errors. 

 It is possible that these errors have crept in by pt^ying 

 too much attention to measurements made on islands and 

 along the sea coast. What is wanted is more numerous 

 and more accurate observations on the sea itself." Further- 

 more, the superintendent of the United States Coast and 

 Geodetic Survey, Mr. O. H. Tittmann, says : — " There is no 

 doubt in my mind that a survey for that purpose would 

 result in obtaining data of great and permanent value, and 

 that it should be undertaken." 



.'\dditional quotations could be given ; the above, however, 

 are representative, and show sufficiently the great import- 

 ance of the proposed work and the fruitful results that may 

 confidently be expected. It is hoped that upon the com- 

 pletion of the maqfnetic survey of the North Pacific the 

 means will be forthcoming for extending the survey so as 

 to include other oceanic areas. An effort will furthermore 

 be made to secure the interest and cooperation of all 

 civilised countries, so that we may look forward to the 



NO. 1843, VOL. 71] 



completion of a general magnetic survey of the accessible 

 portions of the globe within about fifteen years. Thanks 

 to the awakening and renewed interest in magnetic work 

 shown on ali sides, I fully believe that this hope will be 

 realised. 



The matter of prime consideration in magnetic work at 

 sea is the elimination of the effects resulting from the ship's 

 own magnetism as due to her construction and equipment. 

 Such eflects are especially troublesome to eliminate when 

 it is proposed to obtain not only the magnetic declination 

 at sea, but also the other magnetic elements (the dip and 

 the intensity of the magnetic force). The plan therefore 

 to be attempted this year, as worked out by Mr. G. \V. 

 Littlehales, Hydrographic Engineer of the United States 

 Hydrographic Oflice, and Consulting Hydrographer of the 

 Department of Terrestrial Magnetism of the Carnegie Insti- 

 tution, is, in brief, as follows : — " To charter a wood-built, 

 non-magnetic, sailing vessel of about si.\ hundred tons dis- 

 placement, which starting out in summer from San 

 Francisco, shall pursue a clockwise spiral course embracing 

 the entire North Pacific Ocean. The object of planning 

 such a course is to gain continuous advantage throughout 

 the survey of the dynamical agencies of the atmosphere and 

 the ocean, in passing in succession into each of the five 

 degree quadrangles into which the chart ' is divided, and 

 in which observed values of the three magnetic elements 

 need to be obtained. 



" The seasonal shifting of the permanent centres of 

 barometric pressure will cause a variation from month to 

 month of the conditions of wind and current that are repre- 

 sented on this particular chart, but if the departure from 

 San Francisco be taken in the summer, the chain of 

 meteorological events will contribute toward the maximum 

 progress over the course passing thence along the west 

 coast of America to the vicinity of the Galapagos Islands, 

 thence across the Pacific in latitude between two and three 

 degrees north, thence along the eastern side of the Philip- 

 pine Archipelago and the Empire of Japan, thence east- 

 ward in about latitude fifty-two degrees north, thence to the 

 latitude of San Francisco, and thence continuing through 

 the series of areas, bounded by parallels of latitude and 

 meridians of longitude each five degrees apart, lying next 

 on the mid-ocean side of the circuit last made, and pro- 

 ceeding gradually and by successive circuits into the central 

 region of the North Pacific." 



The total length of the course marked out is about 

 70,000 knots ; however, each of the first circuits practically 

 closes at San Francisco, so that, if it is found that the 

 method pursued is not the best, the work can readily be 

 terminated or modified. From inquiries made, it would 

 appear that the entire work of observation and reduction 

 can be accomplished in three years. The cost per month of 

 the field work, inclusive of all expenses and services, will 

 be approximately fifteen hundred dollars. Counting eight 

 months of continuous service per annum, the total annual 

 outlay is estimated at about twelve thousand dollars. 



This project, as a result of careful consideration and 

 solicitation of expert opinion, is believed to be thoroughly 

 feasible. It permits of useful comprehensive results being 

 immediately obtained, and is one which can be interrupted 

 without any important waste of antecedent expense when- 

 ever circumstances may render a discontinuance or a modi- 

 fication of the original plan advisable. 



The region it is proposed at present to survey fortunately 

 contains magnetic observatories in requisite number and 

 proper distribution for furnishing the necessary corrections 

 to be applied to the observed magnetic elements in order to 

 reduce them to a common epoch. Thus continuous records 

 of the magnetic variations required for this purpose will be 

 available from the following stations : — Sitka. Mexico. Hono- 

 lulu, Manila, Shanghai, Tokio. In addition, it is hoped 

 that there may be soon a magnetic observatory in Cali- 

 fornia or vicinity for lending effective cooperation, and that 

 the German Government will continue its magnetic observ- 

 atory at .Apia throughout the period of the survey. Also 

 excellent opportunities for controllinsf instrumental con- 

 stants and obtaining required additional data will be 

 afforded by stations on the coasts and on islands. 



It should also be pointed out that the plan of the courses 



1 The wurse to be followed was shown in red ink on a U.S. Hydro- 

 graphic Office Pilot Chart of the North Pacific. 



