Magnetic Observatories. 171 



tramways had been laid down in Cape Town and its suburbs, and 

 the Royal Observatory, which is w'ithin a mile of the rails was no 

 longer a suitable place for a permanent magnetic observatory. The 

 Council of the British Association had therefore to make their appeal 

 to the Colonial Government. The Association transmitted the resolu- 

 tion of the International Conference — after having considered and 

 approved of it — to the Cape Government through the then High 

 Commissioner, Sir Alfred Milner. The Cape Premier replied that 

 his Government did not regard as practicable the immediate provision 

 of funds for the carrying out of the scheme (B.A. Report, 1899, 

 p. Ixxxv.). 



3. — Purposes Served by a Magnetic Observatory. 



The proper carrying out of the magnetic survey of a country 

 requires the presence of such an observatory. By means of the 

 latter corrections can be made on field observations which have been 

 taken at periods of magnetic disturbance. 



Such an observatory is absolutely essential for the determination 

 of the change in the value of the magnetic elements from year to year. 

 The magnetic chart of the seas neighbouring a land can only be 

 correctly made when this change is known. 



Observation shows that the secular change of the magnetic ele- 

 ments is not a world-wide progress of the magnetic needle moving 

 regularly in certain directions, but that in addition there are local 

 causes at work in certain regions. In other words, a permanent 

 magnetic station in England is of no help to magnetism in South 

 Africa. In South Africa at present it is impossible to tell what the 

 magnetic state of any part of it will be ten years hence. With the 

 establishment of propeily equipped and properly situated observa- 

 tories in combination with a thorough magnetic survey it will, it is 

 hoped, be possible in a few years' time to tell at least two or three 

 years ahead what will be the value of magnetic elements in and 

 about South Africa. 



In this way the safe sailing of the shipping frequenting our 

 shores will be greatly facilitated. Captain Creak says, in his address 

 as President of the Geographical Section of the British Association 

 in 1903, after expressing regret that there was still no permanent 

 station at the Cape : " Of the value of magnetic charts for different 

 epochs, I have much to say, as they are required for purely scientific 

 enquiry as well as for practical uses. It is only by this means we 

 can really compare the enormous changes which take place in the 

 magnetism of the globe as a whole ; they are useful to the miner, but 

 considerably more so to the seaman. Had it not been for the charts 

 compiled from the results of the untiring labours of travellers by 

 land, and observers at sea, in the field of terrestrial magnetism during 

 the last century, not only would Science have been miserably poorer, 

 but it is not too much to say that the modern iron or steel steamship 

 traversing the sea on the darkest night at great speed would have 

 been almost an impossibility ; whereas with their aid the modern 



