May 23, 1859.] ADMIRALTY SURVEYS— VARIATION CHART. 273 



down the Atlantic submarine cable, to make a plan of Bull Arm, 

 Trinity Bay, by Captain Otter and the officers of the Porcupine. 

 In the Bay of Fundy Captain Shortland, with his staif, Messrs. Scott, 

 Pike, Scarnell, and Mourilyan, have surveyed the coast of New 

 Brunswick from St. Martin Head easterly to Wolf Eiver, part 

 of Chignecto Bay, and the Bay of Mines, sounding over an area of 

 400 square miles. 



In the West Indies Mr. Parsons, with his assistants Messrs. Dillon 

 and W. B. Calver, are engaged on the island of Grenada. The 2nd 

 volume of a new edition of the ' West India Pilot,' compiled by 

 Captain E. Barnett, has been published at the Admiralty, and is a 

 great boon to the mariner. After bearing his part in the successful 

 laying down of the Atlantic submarine cable, Commander Dayman 

 on his passage home carried a line of soundings from the Azores to 

 England, showing a depth of 2500 fathoms to within 60 miles of 

 the edge of the 100 fathoms shelf which extends from the Land's 

 End, thus indicating that a more sudden dip in the bed of the 

 ocean exists here than was found to the westward of Valentia, in 

 Ireland,, 



Variation Chart. — I had occasion to mention last year that a 

 Variation Chart of the world, showing at a glance the curves of 

 equal magnetic variation, was in preparation at the Admiralty by 

 Mr. Fred. T, Evans, e.n., chief of the Compass Department. This 

 chart has since been published ; and judging from the testimony to 

 its value borne from all quarters, it has proved even a more accurate 

 and useful document than was anticipated. I^he whole of the curves 

 are reduced to the epoch of 1858; the chart gives also the annual 

 change of variation which is constantly in progress, and this in places 

 exceeds seven minutes yearly. This may appear a small amount, 

 but when we consider that in the greater part of the charts by 

 which our merchant ships are navigated, the variation has not been 

 corrected for thirty, forty, and even fifty years, the practical sailor 

 will at once see a fearful source of error that may, unsuspected, 

 exist. The error of a quarter of a point of the compass in a mn of 

 500 miles would amount to 25 miles, and this, in navigating a long 

 narrow sea or strait, as the Adriatic or Eed Sea, might readily lead 

 into dangers, and this error has doubtless been one of the many 

 causes of shipwreck. By this chart the means of correcting the 

 variation in all charts are now within the reach of every one for a 

 few shillings, and we trust it will be largely circulated. It is 

 gratifying to know that a strong expression of the approbation of 



