FLYING SQUIRREL. 77:; FLY-WHEEL. length of the body; ii lives solitary in the forests. Its fur is of little value, but ikin are sometimes mixed with those of the graj squirrel, to impose on the purchaser. The most common North American species [Sciuropterue • •■'» cella), common from the Gulf of Mexico to Upper Canada, is fully live- inches long, plu tail equally long, it is brownish-graj above, white beneath, and a black line surrounds tin- orbit, of each eye. In the 5Tuk 'egion of Alaska this species is replaced by a much larger one (Scvuropterus Yvkonensis) , but it seems to be a very rare animal. All the flying squirrels inhabit woods, and the night i- their time for activity. Thej fed no! only on nuts and young shoots .if trees, bul also are said to kill and eat, small birds, and to rob birds' nests. They are easy id' domestication, but are apt to bite, and do mischief to furniture and hangings, especially by gnawing stuffs to pieces as material for their nests. These are naturally placed in some cranny of a hollow tree, preferably a deserted woodpecker's hole, but may be placed within a bouse. In gliding from tree to tree the flying squirrel descends obliquely, and with very rapid motion, until near the tree which it seeks to reach, when it wheels upward, and alights on the trunk, fitly or sixty feet is the ordinary length of its flight. See Squirrel, and the authorities mentioned thi under; and Plate of Squirrels. The name is also applied in Australia to flying phalangers (q.v. ), and in Africa to the scale tailed squirrels of the family Anpmaluridse. These little creatures, which belong in West and Central Africa, much resemble American living squirrels in appearance and habits, but the tail is mure slender, and has on its inferior surface and margins, near the root, a series of large imbricated scales, that are of service in climbing; the parachute is distended and supported by a stiff cartilaginous process from the olecranon. Consult Proceedings Zoological Socit ty of Lon- don (London, 1S74-75).
FLY MUSHROOM, or FLY AMANITA. See Amanita ; Fungi, Edible axd Poisonous.
FLYNT, Josiah (properly Josiah Flynt Willard) (1869–). An American sociologist and author, born at Appleton, Wis. He was educated at the University of Berlin in 1890–95, and after several years of experience as a professional va-grant, published in 1899 Tramping with Tramps, a novel and picturesque study. His further works dealing with the lower and criminal classes include The Powers that Prey (1900), a collection of short stories written in collaboration with Francis Walton: Notes of an Itinerant Policeman (1900); The World of Graft (1901), also a volume of short stories: and The Little Brother (1902), his first sustained attempt in fiction.
FLY-SNAPPER. One of the names of a rare and very beautiful crested fly-catcher [Phaino pepla nitens) of the southwestern United stale-. It is entirely rich lustrous black with steel-blue or greenish reflections; and with a large white space on the inner webs of the wing-quills. Its length is about seven and one-half inches. The female is brownish gray, hut crested. It fre- quents bushes in the desert regions of Nevada, Arizona, and southern California. It also feeds extensively on various berries, and has, in short, much 1 tie habit. - and manni ._;. lis 1 ling call' ; and it B 11 in ., bU»h "i t M'.-, and laj s two thickl] 1 H it Ii .huh hi ..>,', 11 and purpll [mo 1 totally b a ill < <»n.- ../ thi Colorado Valley (Washington, 1-. FLY-UP-THE-CREEK. A local nunc in tin- 1 mi...! States i"i tin- littli shitepoke | 1 rdt ./ in coi on through- out t he I Ilile.l States "el .,111 ii. I 11 I ana. la. See Heron. FLY-WEEVIL. A local name in thi United stale- for the grain-n See I i|; I- 1 -| , 1 FLY-WHEEL. A heavy wheel attached 10 the revolving shaft of a steam-engine to as an accumulator and equalizer ..1 power. Us action depend- upon tin- mechanical law thai a bodj '.11cesctin1noii.nl retains a certain amount ..I ni..ing force or momentum which has ovei '"iiie before unit ion .. ,1 . thus, a heavy wheel once set to rotating bj s external Fori as the piston-rod of a steam-engine, continues to rotate by virtue of its stored energy or 1110- meiiiuiii after this externa] force ceases to act. In a steam-engine the function of a fly-wheel is: (1) To store up excess of - 1 from the piston during the first pail of it- stroke on der full steam pressure, an. I to give it oul when, during the latter part of the stroke, the effort has grown less because of decreased pressure due tu the expansion of the steam; (2) t.. equalize Hi., variation in the leverage with which the vary ing -team effort acts upon the crank to revolve tin- -haft; (3) to give out or absorb energy when variation in the external load or r.-i-lan cur- suddenly. The fly-wheel is. therefore, scribed, an accumulator and an equalizer, and tin- reserve which il stores will be greatei a- it- mass is greater, and the leverage greater with which that ma-- act-. Large ma-- an weighl and consequently great friction on the shaft-bearings. Large leverage or large radius mean- more space required for the wl I and in- creased centrifugal force tending to disrupt it- rim. The designer of a fly-wheel ha- t.. integrate these different factors t.. meet the requirements ..f space, -| I ol rotation, and other governing conditions. Modern practice shows a tendency t.. adopt smaller diameter wheels than wa customary; in early engines 30-foot fly-wheels were often t" be met, hut now is to -jo feet are large diameter-, and in cent 1 e crank high-S] 1 engines six feet has become a large -ixe. The strains which are set up in a fly-wheel b of the work which it has to do are. first, a toi si.mal strain tending to twist the spokes off the huh. and second, a -train due to centrifugal force which tends in burst the rim. A fly-wheel can easily be designed to resist torsional .-train-, but there is no possible way t.. overcome the e.-niri fugal force, hence for a given material there is a definite speed at which disruption will regardless of the amount of material used. A re- cent authority gives the following simple formula for figuring the disrupting speed of fly-wheels having solid, single-piece rims:
In this formula r represents rim-speed in feet per second at which disruption occurs, s repre-
