The Weather Department Of The Board Of Trade.

been a recognised fact that they cannot be safely navigated Avithout the compass being , as it is termed , " adjusted" —i . e ., Avithout the deviations being corrected either mechanically by magnets or by a table of errors ; but at first the correction of each ship AA as a separate and independent problem .

Now the case is different . The theory of the deA iation , its causes and its laAvs , are now thoroughly understood and reduced to simple formulas , leaving the numerical magnitude of a certain small number of quantities to be determined by observation for each ship separately ;

and , further , by recording , reducing , and discussing the deviations which have been observed in the ships of the Royal Navy of different classes , numerical results as to the value of these quantities in ships of each class kaA r ebeen determined , Avhich

promise to be ofthe greatest use m facilitating the complete determination of the deAniatioii and its correction , and in suQ-Q-estino- modes for constructing iron ships , and in the election of the position of the standard compass . The science of magnetism , in its relation to navigation , is , in fact , in

a position in some degree analogous to that in Avhich . the science of astronomy at one time Avas . The principles of the science have been established , the formulas have been obtained , but numerical values are Avanted , which can be derived only from a large number of observations systematically

made and discussed . At present , these numerical results have been obtained from , and are applicable to , the ships of the Royal Navy only . Without some systematic direction , the mercantile marine can neither derive the full benefit of nor

contribute its due share to the advance of the science . The Board of Trade is already empowered by Act of Parliament to grant certificates to merchant ships of which the compasses have been properly adjusted ; it would be needful only to

extend the power to accomplish all that ex ] : > erience has demonstrated as indispensable to safe navigation , namely , proper correction of compasses , advancement of the science of compass-deviation , and the education of masters and mates in that science . In the ships of the Royal Navy , there is

placed a standard compass , distinct from the steering-compass , " fixed in a position selected , not for the convenience of the steersman , but for the moderate and uniform amount of the deviation at and around it . The shi p is navigated solely by this standard compass . But in merchant shi

ps the corrected ( or standard ) compass is also the steering-compass , and the position of the steeringcompass renders it liable to great disturbance ; besides which the method of correction employed is continually deranged by tlie change which , as is Avell knowntakes place in the magnetism of iron

, ships . The method adopted by the Admiralty is one which can be used Avithout danger ; but the same cannot be said of the other , because of the wrong placing of the compass .

The temptation to use the cheapest method is so strong , and the risk thereof so great , that the Board of Trade may fairly be called on to require that every iron passenger-ship shall carry a standard compass , distinct from the steeringcompass , in a selected situation at a certain

distance from all masses of iron ; that the original deviations of this standard compass shall not , in ordinary cases , exceed a certain limited amount ; that on each occasion of the compass being adjusted , a table of the deviations be furnished to the master , and returned to the Board of Trade ;

and that , if corrected by magnets , a return be made of the positicn of the magnets and of every subsequent alteration of their position .

Besides these requirements , there are other practical matters in Avhich a capable chief of the compass department might act Avith advantage . By communicating Avith the different ports , he might bring about a uniform system of compass adjustment , which would be generally understood

by shipmasters . He must suggest means of facilitating the adjustment by meridian marks on shore , the laying down of moorings , and so forth . And he might act as assessor in investigations into the loss of iron ships , iu cases in Avhich there was any possibility of the loss having been occasioned by

compass-error . As regards the advancement of the science of the deviation , and the education of masters and mates , there cannot be a difference of opinion . No one Avill contend that these particulars should be left to chance or ignorance .

The Memoranda conclude Avith a declaration that it seems desirable to establish a department of the Board of Trade under a competent superintendent , AAdio should devote his time to the Avhole subject . Almost all the adA r ances which have hitherto been made in the science , and AA'hich have

placed England at the head of the science , are due to there haAdng been for the last twenty-five years one officer charged by the Admiralty with this duty almost exclusively . Such an officer becomes the depositary of all that is known on the subject , and has no difficulty in obtaining the best scientific assistance . It is understood that there would be

no practical difficulty , and there would be many advantages in the present state of the science in having the superintendence of the compasses of the Royal and . Mercantile Marine united under one head , Avith competent assistants in the two branches of the service . Any intelligent man

could speedily be instructed in all that Avould be necessary to enable him to discharge the duties of assistant for the merchant navy . In selecting such an assistant , it would probably be more important to look to general ability , intelligence , docility , and the habit of , and aptitude for ,

dealing Avith men , and particularly with masters of merchant vessels , than to any previous knowledge of the subject . — Athenceum .