

FORT HALL 



3263 



FORTIFICATION 





The Firth has great strategic im 

 portance. During the Great War 

 it was a base of the Grand Fleet ; 

 many defences, forts, protective 

 booms, etc., were constructed, and 

 in the Firth off Inchkeith the Ger- 

 man fleet surrendered, Nov., 1918. 

 See Rosyth. 



Fort Hall . Settlement in Kenya 

 Colony, E. Africa. It is situated be- 

 tween Nairobi and Mount Kenya, 

 and is 4,500 ft. above sea level. A 

 branch line from the Uganda Rly. 

 has reached the Thika river (32 m. ) 

 and is to be continued to Fort Hall. 



Forth and Clyde Canal. 

 Waterway extending from Grange- 

 mouth, on the Forth, to Bowling, 

 on the Clyde. It was constructed 

 between 1768-90 at cost of 

 330,000, and has a length of 

 39 m. Since 1867 it has been the 

 property of the Cal. Rly, but no 

 great volume of traffic uses the 

 canal regularly. 



Forth Bridge. Railway bridge 

 in Scotland, begun in 1882 and 

 opened for traffic in 1890. By its 

 construction across the Firth of 

 Forth a long detour of the rly. 

 westward was obviated and direct, 

 connexion between Edinburgh and 

 the N. side of the Firth established, 

 while its clear height of 150 ft. 

 and long spans enable vessels of 

 any size or type to pass below it. 



From the engineer's point of 

 view, it marked an epoch in the 

 history of bridge building. Its 

 enormous clear spans of 1,710 ft. 

 between supports were rendered 

 possible by the use of steel and by 

 the cantilever design of the super- 

 structure. The bridge, which carries 

 two railway tracks, is slightly over 

 1} miles in length. There are 

 three main piers from which the 

 six cantilever arms rise and project, 

 the ends of which, in the main 

 spans, support and are connected 

 by long girder spans. The height of 

 the cantilevers, over the piers, 

 above water level is 361 ft. The 

 main compression members of the 

 cantilevers consist of steel tubes in 

 some cases 12 ft. in diameter. 



The extremities of the end canti- 

 levers rest upon masonry piers 

 whence the rly. is carried to the 

 shore on approach viaducts com- 

 prising a number of comparatively 

 small steel bridge spans and ma- 

 sonry arches. Each main river pier 

 consists of four circular masonry 

 supports resting upon caissons 70 ft. 

 diameter, and sunk to a depth of 

 from 70 ft. to 90 ft. below water 

 level. The structure, designed 

 by John Fowler and Benjamin 

 Baker, comprises 51,000 tons of 

 steelwork and 142,000 cubic yds. 

 of masonry, cost nearly 3,000,000, 

 and occupied seven years to con- 

 struct. See Bridge, illus. and plate. 



FORTIFICATION : PAST AND PRESENT 



Sir George O. Aston, K.C.B., Author o War Lessons, New and Old 



The principles of fortification are here outlined. The article 

 Fortress should also be read, as well as those on Strategy, Tactics, 

 and War. See also Artillery and articles on Antwerp : Mctz ; 

 Verdun, and the great fortresses of the past 



From the siege of Troy the history 

 of the world's wars is filled with 

 heroic tales of human ingenuity 

 displayed in the attack and defence 

 of fortified places. Fortifications 

 confer the power of prolonged re- 

 sistance upon forces which are in- 

 ferior in numbers, mobility, equip- 

 ment, or moral to their enemies. 

 Thus Wellington in the Peninsula 

 took shelter behind the celebrated 

 lines of Torres Vedras when his 

 army required a safe refuge for re- 

 cuperation, and in the Great War 

 of 1914-18 both sides made use of 

 the art of the engineer to enable 

 their armies to hold their own on 

 the defensive while collecting men 

 andmunitionsf or aaerious offensive. 



The advantages conferred upon 

 armies by fortifications are tem- 

 porary. Francis Bacon wrote truly 

 that " walled towns, stored ar- 

 senals, and armouries . . . ordnance, 

 artillery, and the like, all this is but 

 a sheep in a lion's skin, except the 

 breed of the people be stout and 

 warlike." It is not fortifications 

 but men that decide the fate of 

 nations. Fortifications which af- 

 ford all-round defence to their 

 garrisons are called fortresses. 

 While these can be of great value if 

 skilfully applied, they sometimes 

 have a harmful effect upon the 

 commanders of field armies. Ba- 

 zaine's army, sheltering behind the 



provisions were scarce and means of 

 communication bad, the issue of a 

 war was often determined by the 

 attack and defence of fortified 

 places, and the history of war be- 

 came a history of sieges. Large 

 quantities of foodstuffs were col- 

 lected in great fortresses where the 

 people took refuge while the at- 

 tackers tried to pass the fortified 

 lines in order to reach them. If 

 surprise, assault or bombardment 

 failed, the attacking forces were 

 obliged to resort to regular siege, 

 approaching by cunningly devised 

 forms of entrenchment called 

 " parallels " and " saps," and by 

 mining galleries, at the same time 

 " investing " the place to starve 

 out the garrison. 



When the mobility of armies 

 was increased by improvements in 

 roads and wheeled transport, a 

 complete change came over the 

 nature of land warfare, and the 

 value of fortresses now lies in the 

 influence they can exert upon the 

 operations of field armies. If placed 

 where important roads and rlys., 

 needed by an invading army, con- 

 verge towards the crossings of ob- 

 stacles such as rivers or marshy 

 country, a well-placed fortress can 

 delay an invader's advance. The 

 delay imposed upon von Kluck's 

 army by the forts of Liege in 1914 

 was one of the factors enabling 



active part in the Franco-Prussian 

 War, and Sir John French was 

 sorely tempted to seek the protec 



defences of Metz, took no further Manoury's army to assemble N. of 



Paris in time to play an important 

 part in the victory of the Marne. 

 Again, the need to detach forces 



tion 'of the fortress of Maubeuge to guard the communications of an 



invading army against the garri- 

 sons of fortresses may seriously re- 

 duce its strength in decisive battle. 

 Von Kluck and von Bulow, having 

 detached forces to watch the Bel- 

 gian army in Antwerp and the gar- 

 rison of Maubeuge, were too weak 

 to perform their task in France. 



after the battle of Mons. 



Fortifications may take the form 

 of " permanent " works, erected 

 in time of peace, or of tempo- 

 rary " field " defences, constructed 

 when and where they may be re- 

 quired in time of war. At certain 

 periods in European history, when 



Firth of Forth. Layered map showing the heights ot the surrounding hills 



