PENELOPE 



PENGUIN 



beat is 2ir J (l/g) where / is the 

 length of the string, and g is the 

 acceleration due to gravity. Thi3 

 law applies only for small oscil- 

 lations, and for such the period 

 of beating is constant at any par- 

 ticular place Since, however, it 

 varies with jr, the same pendulum 

 taken to different parts of the 

 earth, or to different altitudes, 

 serves as a means of calculating the 

 force due to gravity. 



Any solid object suspended from 

 a horizontal axis performs os- 

 cillations similar to those of a 

 simple pendulum, and in dynamics 

 is called a compound pendulum. A 

 seconds pendulum is one that 

 makes a complete beat in one 

 second. A compensation pendulum 

 is one which is compensated against 

 changes of temperature. Without 

 some such compensation the 

 length of an ordinary pendulum, 

 usually made of a metal rod with a 

 weight attached, would increase in 

 hot weather, and the pendulum 

 therefore beat slower. Such pen- 

 dulums take advantage of the 

 different rates of expansion of dif- 

 ferent materials, and are very 

 necessary in the construction ol 

 astronomical clocks. 



Fig. 1 shows a gridiron com- 

 pensating pendulum, in which 

 a, a, a, a are steel rods and 6, 6, 6, b 

 are brass rods. The expansion of 

 the steel rods lowers the bob of the 

 pendulum, while the expansion 

 of the brass rods raises it, the 

 two thus compensating one an- 

 other. Fig. 2 shows a mercurial 

 compensating pendulum, the ex- 

 pansion of the mercury tending to 

 raise the centre of gravity of the 

 bob, and that of the supporting 

 rod to lower it. 



Besides its use in clocks and foi 

 obtaining the value of g, the pen 

 dulum has been used in the famous 

 experiment of Foucault to show 

 the rotation of the earth. A 

 ballistic pendulum is one used to 

 measure the velocities of shot or 

 bullets. The bob of the pendulum 

 is replaced by a wooden block into 

 which the shot or bullet is fired. 

 The distance through which the 

 block moves and the consequent 

 time of oscillation of the pendulum 

 enables the velocity of the pro- 

 jectile to be calculated. See 

 At wood' s Machine ; Ballistics ; 

 Clock ; Foucault. 



Penelope. In Greek legend, 

 wife of Odysseus (q.v. ). The long 

 absence of her husband caused a 

 number of suitors for her hand to 

 come to the royal palace at Ithaca, 

 where, in spite of her refusals, they 

 lived riotously. She promised to 

 make up her mind as soon as she 

 had finished a garment, of which 

 she secretly unwove each night as 



much as she had woven in the day 

 Pron. Pe-nellopy. 



Peneplain. Name given to an 

 area which has been reduced to a 

 surface so nearly a plain (pen?., 

 almost) that it could not be distin- 

 guished from one by the eye. The 

 plains of the Hudson Bay and Gulf 

 of Bothnia (Baltic Sea) areas, and 



Fig 



FigZ 



a a 



Pendulum. Examples o! compen 

 sating pendulums. See text 



of the New England States, are good 

 examples. These are the remains 

 of ancient highlands which have 

 been worn down by frost, ice, rain, 

 rivers, etc. Pron. peeny -plane. 



Penetanguishene OR PENE- 

 TANG. Town of Ontario, Canada. 

 It is on the G.T. Rly., on an inlet 

 of Lake Huron, 32 m. N.N.W. of 

 Harrie in Simcoe co. It engages in 



Penelope, the wife of Odysseus. 



From a Greek sculpture in the 



Vatican, Rome 



the lumber and leather trades. 

 During the war with the U.S.A. 

 the town was fortified as a Cana- 

 dian naval station. A regiment of 

 French scouts, the bulk of the 

 garrison, was rewarded with a 

 grant of land and exemption from 

 taxation, a privilege still enjoyed 

 by their descendants. Pop. 4,000. 



Peneus. Ancient name for the 

 river of Greece now known as the 

 Salambria (q.v.) or Salamvria. 



Penge. Urban dist. of Kent, 

 England. Adjoining Lower Syden- 

 ham, on the Surrey border, it is 6 m. 

 S. of London, on the S.E. & C. and 

 L.B. & S.C. Pvlys., and is linked up 

 with the surrounding clists. by 

 trams and motor-'buses. Formerly 

 a detached hamlet of Battersea, 

 and until about 1830 merely a 

 common, part of it was absorbed 

 for the Crystal Palace and part 

 given over to the builder. The 

 Watermen's and Lightermen's Asy- 

 lum dates from 1839, and has a 

 museum of marine and other curi- 

 osities. Pop. (1921), 26,278. 



Penge Case, THE. British cause 

 celtbre. In Sept., 1877, there ap- 

 peared before Mr. Justice Hawkins, 

 at the Old Bailey, on a charge of 

 murder, Louis and Patrick Staun- 

 ton, the latter's wife, Elizabeth 

 Ann, and her sister, Alice Rhodes. 

 The victim was Harriet Staunton, 

 wife of Louis, a woman of weak 

 intellect, with a fortune of 3,000. 

 Within a few months of marriage 

 Louis Staunton had deprived her 

 of her last halfpenny, and then 

 determined to make an end of her. 

 so that he might marry Alice 

 Rhodes. In 187(5 the brothers 

 were living at Cudham, Kent, and 

 in a garret at Patrick's house 

 Harriet was imprisoned and slowly 

 starved to death. When she was on 

 the point of death, they removed 

 her to lodgings at Penge. She died 

 on arrival there, and the doctor at 

 Penge communicated with the 

 coroner. All four prisoners were 

 convicted and sentenced to death. 

 Alice Rhodes was pardoned, the 

 sentences on the other three being 

 commuted to penal servitude for 

 life. The case is famous for the 

 speech for the defence by Sir 

 Edward Clarke (q.v.)., and is de- 

 scribed in his Autobiography. See 

 The Trial of the Stauntons, ed. J. 

 B. Atlay, 1911. 



Penguin. Name given origin- 

 ally to the extinct great auk, but 

 now applied to the several genera 

 of the order Impennes. They are 

 sea-birds with boat-shaped bodies, 

 legs placed very far back, the toes 

 webbed, and the wings useless for 

 flight. The latter are entirely with- 

 out quills and the feathers cover- 

 ing them are small and scale-like. 

 They are incapable of flexure, but 



