FLANGE 



Flange (Fr. flanc, flank, side). 

 Projection which guides, strength- 

 ens, or affords a means of attach- 

 ment. CircumferentiaPflanges are 

 used on wheels which run on rails 

 or over which rails, belts or ropes 

 run, to prevent displacement. In 

 metal beams or girders the central 

 part, or web, has a flange at one 

 edge or, more usually, at both 

 edges, to give lateral stiffness and 

 take the bending stresses of tension 

 and compression. Annular or oval 

 flanges are used on the ends of 

 steam and other pipes which are 

 subject to heavy pressures, so that 

 the pipes may be drawn and held 

 together by bolts. The hubs of 

 wire-spoked wheels have flanges 

 to which the heads of the spokes 

 are secured. See Girder. 



Flank. Military term used for 

 the side of a unit, whether in 

 column, line, mass or any other 

 formation. On the march troops are 

 protected by flank guards, and, 

 when taking up a position, by 

 outposts, unless the nature of the 

 ground makes an attack im- 

 possible. See Tactics. 



Flank Guard. Patrols or bodies 

 of troops detailed to protect the 

 main body from flank attacks 

 while on the move or at rest. The 

 strength of the flank guard and its 

 distance from the main body de- 

 pends on the size of the latter and 

 the nature of the country. It 

 should always be strong enough to 

 hold up any attack until the main 

 body has had time to deploy into 

 fighting formation, if the attack is 

 too strong to be defeated by the 

 flank guard. A large flank guard 

 must protect itself by advanced 

 and flank guards so that it can 

 move in close formation. 



Flaniian Isles. Cluster of seven 

 small islands in the Outer Hebrides, 

 Ross and Cromarty, Scotland. 

 Called also the Seven Hunters, they 

 lie 16 m. N.W. of Gallon Head, 

 Lewis Island, and contain many 

 Caledonian remains. They are 

 the Insulae Sacrae of Buchanan. 

 Large numbers of sea-fowl fre- 

 quent them. 



Flannel. Soft woollen cloth 

 used for clothing, blankets, etc. 

 Highly absorbent, it is eminently 

 adapted for wearing next the skin. 

 The word is probably of Celtic 

 origin (cf. Welsh gwlan, wool). 

 Wales is the original home of the 

 flannel industry, and has long held 

 flannel fairs. Falstaff calls Sir 

 Hugh Evans the " Welsh flannel." 

 Welshpool, in Montgomeryshire, 

 formerly the chief seat of the manu- 

 facture, has been superseded by 

 Newtown. Lancashire and York- 

 shire are noted for flannels, par- 

 ticularly the town of Rochdale. 

 See Blanket, 



3191 



Flannelette. Cotton imitation 

 of flannel, used for pyjamas, under- 

 wear, etc. The term was first used 

 towards the end of the 19th cen- 

 tury. Flannelette is now made 

 extensively in Europe and the 

 U.S.A., and is a popular clothing 

 material, though it lacks the ab- 

 sorbent properties of flannel, and 

 is liable to catch fire. A " non-flam" 

 flannelette has been patented. 



Flare. Fireworks of the nature 

 of coloured fires. They are used in 

 warfare to illuminate portions of 

 the front at night, and in some 

 cases are arranged so that they are 

 automatically ignited if anyone 

 moving about stumbles over a 

 trip wire placed in front of the 

 position. Screens should be ar- 

 ranged behind the flares so that 

 the enemy troops are illuminated, 

 while their opponents remain in 

 the shadow and are not incon- 

 venienced by the light. Small 

 hand flares are used for both 

 illumination and signal purposes, 

 and generally burn for about 

 three minutes. Larger ones may 

 be thrown from trench howitzers. 

 Flares intended to illuminate the 

 ground usually contain a mixture 

 of powdered magnesium and a 

 chlorate or nitrate of one of the 

 alkali metals. They give an in- 

 tense white light, throwing strong 

 shadows. Similar flares were also 

 employed on board ship to illumi- 

 nate particular operations, as at 

 Zeebrugge and Ostend. Signal 

 flares are frequently required to 

 give a coloured light, and for this 

 purpose the following compositions 

 are typical : 



Ked 



Green 



BluejY 



eilow 



Potassium 

 chlorate . . 



Strontium 

 carbonate . . 



Shellac . . 



Barium 



chlorate . . 



Milk sugar . . 



Sodium nitrate 



Sulphur 



Antimony sul- 

 phide 



Lampblack . . 



Basic copper 

 carbonate . . 



Calomel 



78 



See Fireworks. 



Flash. Bow of broad black silk 

 ribbon with 

 long ends, 

 which is at- 

 tached to the 

 back of the 

 tunic collar of 

 the Royal 

 Welch Fusi- 

 liers. No au- 

 thentic explan- 

 ation of this 

 custom is forth- 



coming, but in 



Flash. Distinctive 



bow worn by the . 



Royal Welch 



Fusiliers 



FLASK 



an inspection report of 1786 it was 

 noted that "the officers of this 

 regiment wear the hair turned 

 up behind." Evidently the flash 

 is a survival from the days of 

 queues and hair powder ; it is 

 issued officially as an item of 

 " personal clothing." See Uniform. 

 Flashlight Photography. 

 Photography by the brilliant light 

 obtained by burning the metal 

 magnesium. It is used chiefly for 

 portraits, groups, and interiors of 

 moderate size. In one apparatus 

 fine magnesium is blown through 

 the flame of a spirit lamp, but the 

 magnesium is usually combined 

 with chlorate or perchlorate of 

 potash, and fires readily on the 

 application of a taper or electric 

 spark. The chief drawback to 

 these " flash-powders " is the 

 smoke which is produced by them. 

 See Photography. 



Flash Point. Temperature at 

 which an inflammable liquid gives 

 off vapour which takes fire when a 

 flame is passed over the surface. 

 It is also used for that at which the 

 vapour that collects forms an in- 

 flammable mixture with the air in 

 the closed vessel of the test appar- 

 atus. The former is called the 

 open and the latter the closed test. 

 The test is specially applied to 

 petroleum products. The open test 

 was employed in accordance with 

 Petroleum Acts, 1868 and 1871. 



In consequence of the unsatis- 

 factory results, Sir Frederick Abel 

 investigated the matter, with the 

 result that the Petroleum Act, 

 1879, was passed, legalising the 

 closed or Abel test. The new 

 standard was fixed at 73 F. 

 (22-8 C ). The Abel apparatus, 

 which is standardised by the board 

 of trade before use, is employed 

 in this country for low -flash oils, 

 and by order in Council, 1907, 

 the Abel-Pensky apparatus for 

 high-flash oils. For determining the 

 flashing point of the heavier mineral 

 oils modifications of the above ap- 

 paratus are used. These are the 

 Pensky -Martens and Gray appara- 

 tus. See Oil ; Paraffin ; Petroleum. 

 Flask. Word used in various 

 senses. (1) In founding, a wooden 

 or iron box or frame-like structure 

 for holding the sand or material 

 forming a mould into which molten 

 metal is poured for making a cast- 

 ing in a foundry. The flask com- 

 5 rises a cope, or top member ; a 

 rag, or bottom member ; and, 

 when used, intermediate members 

 termed cheeks. If the mould is 

 contained in two or more members, 

 the structure is known as a two- 

 part flask, a three-part flask, etc. 

 (2) A vessel of glass, metal, etc., 

 usually having a neck, and pro- 

 vided with a body portion which 



