12 



GEOGEAPHICAL POSITIONS. 



3. Falmouth. — Dr. Tiarks ascertained, in the summer of 1822, by the comparison of 

 sixteen excellent chronometers, carried backward and forward between Greenwich and 

 Falmouth, that the western longitude of the latter had been given at 4*4 seconds of time, 

 or 1' 6" of arc too little, by the first Trigonometric Survey. In consequence, twenty-nine 

 of the best chronometers belonging to the Admiralty were subsequently committed to the 

 care of the doctor, and a vessel was appointed wherein he was to sail, backward and forward, 

 between Dover and Falmouth, until the longitude in time, between these stations, and 

 between them and Portsmouth, as an intermediate station, was settled beyond any 

 doubt. The result was, as to all places on the South Coast of England, between the 

 meridians of Greenwich and Falmouth, if 1 second be added to every 4 minutes of longi- 

 tude, as given by the original Survey, the exact longitude, according to the chronometers, 

 will be obtained. These differences have since been entirely settled by the re-examination 

 of the triangles, now completed. 



VAEIATION OF THE COMPASS. 



In the latter part of this volume, some observations on the general suhjeot will be found, 

 among which, as to the secular change, which requires attention, the more especially 

 from the care demanded in the navigation of iron ships. In these Tables we give the 

 apjn-oximate variation for the year 1895, reserving such remarks upon former results for 

 the section specially devoted to the subject. 



The Variation is now decreasing on the Coast of Englard at an average rate of about 

 5J' or 6' per annum, according to the most recent observations at the Greenwich Obser- 

 vatory, varying irregularly from 5' to ^V between successive years. The rate at which it 

 is increasing or decreasing in this and other regions is also shown on the special Diagram 

 given hereafter. 



2. ISLANDS AND COASTS OF SCOTLAND. 



LAT. N. 



LONG. W. 



AUTHORITIES. 



Edinburgh ; the Observa- 

 tory [1] 



Inchkeith Lighthouse 



Isle of May, Lighthouse... 



East Lomond, 1,461 ft. ... 



Fifeness 



BeUPtock, Lighthouse 



Dundee Law 



Buddon-ness, High Light 



Arbroath, the Abbey 



Red Head 



Montrose, Scurdy Ness, 

 Lighthouse 



Girdleness, Lighthouse . 



Aberdeen, Marisch-al Coll. 



Aberdeen, North Break- 

 water Lighthouse 



Belhelvie or Orrock, Dove- 

 cote 



Buchanness, Ligiithouse... 



Peterhead, Old Mill 



3 

 3 

 2 

 3 

 2 

 2 

 2 

 2 

 2 

 2 



10 54 



8 5 



33 22 



13 10 



35 

 23 



59 10 

 44 54 

 34 53 

 29 24 



2 26 6 

 2 2 40 

 2 5 42 



2 4 6 



2 3 57 

 1 46 22 



1 47 32 



o ; 

 19 30 



19 5 

 19 25 



19 5 



The Grand Trigonometri- 

 cal or Ordnance Survey of 

 Great Britain. 



