GEOGEAPHICAL POSITIONS. 



27 



6. Brussels. — The Observatory at Brussels was considered, by the observations con- 

 ducted therein, to be in latitude 50° 51' 10-7", longitude 0^ 17" 290^ in time, East of 

 Greenwich. Although this position may not affect those of the coast, which were obtained 

 by an independent process of triangulation, yet the change in the assumed longitude of 

 the Observatory of Paris, with corresponding alterations in the relative connexions 

 between that and other observatories, affect the longitudes of places on the coasts, in 

 such a minute degree, it is true, that it is perfectly inappreciable by means at the ordinary 

 sailor's command ; yet it is noticed here to show to what refinement these operations are 

 carried on. It will also demonstrate the almost insuperable difficulty there is in arriving 

 at an exact conclusion. This subject has been alluded to in connexion with the Edinburgh 

 Observatory, and will be hereafter with that of Paris. 



In 1859, a series of instantaneous electric signals was made to connect the Observatories 

 of Brussels, Berlin, Altona, &c. ; and the longitude of Brussels, as given by M. Quetelet, 

 came out as 17" 28*9^, or 4° 17' 30*5" East of Greenwich — a very close approximation to 

 the independent assumption. Later observations, however, have determined the position 

 as given in the Table. 



The Variation of the Compass is now decreasing on the Coasts of Denmark, North 

 Germany, &c., at the rate of 7^' per annum. 



6. COASTS OF FEANCE. 



LAT. N. 



LONG. E. 



AUTHORITIES. 



Northern Coast. [2] 



Paris, Observatory [1] 



Belgian Frontier, Corps de 

 Garde 



Bergues, great spire 



Drmkirk, Belfry tower 



Heuguenaar Tower 



Cassel, Western Mount ... 

 Gravelines, Church spire... 

 Oye, Station in Survey ... 

 Calais Spire 



Lighthouse 



Coquelles, West Mill 



Cape Blanc-Nez 



Mont Couple, summit 



Cape Gris-Nez, Lighthouse 



Ambleteuse, Windmill ... 



Boulogne, Colonne de la 



Grande Arm^e , 



Cathedral , 



Cape d'Alprec'h, Lightho 



Lornel Point 



Etaples Church 



Touquet, South Light 



Berck, Lt. on Haut-Banc 



Cayeux, Lighthouse , 



Bt. Valery-sur-Somme, Lt 



Treport Steeple 



Dieppe, Semaphore 



St. Jacques C Lurch , 



The French Government 

 Surveys originated from the 

 triangles intended merely for 

 the admeasurement of the 

 degrees of the meridian in 

 France, but ultimately carried 

 on throughout the kingdom. 

 These were comnaenced by 

 M. Picard, who effected an ad- 

 measurement between Paris 

 and Amiens in 1669, and 

 finallj' completed by Messrs. 

 Mechain and Delambre, in 

 1798; after having exercised 

 the abilities and industry of 

 M. Cassini the elder, his son, 

 and grandson ; and since then 

 of MM. Miraldi and de la 

 Caille, with other of the most 

 eminent French astronomers, 

 &c., up to the present time. 



