36 



THE POPULAR EDUCATOR. 



6. <f e P w > I bear, (OI) fut. OKTU ; (ENEFK), aor. 2 fivtynov (less 



often -rjvfyKa), -ts, -f, opt. tvfyKaifj.i, -eie, and -oi/xi, -01, inf. 

 fveyKftv, part. eveyiccav, imper. fveyice, -eroi, and -area, etc., 

 (ENEK-) perf. evrjvoxa, perf. mid. or pass, evyvey/nai (-yai, 

 -yKTai or fj/r/ce/croi), aor. mid. Tjvfy/cajurjj/, ej/f-y/cai, -ao~6ai, 

 -a.jj.fvos, aor. pass, r/i/e^flr/v, e^e^^t/ai ; fut. eye^r/a^ai, less 

 often oiffdritro/j.ai. 



7. <pr),iu, I say, imperf. (pr/c, (En) aor. 2 ejTroj/ (more seldom 



ejira), enrai, eiiroif.ii, flirt, -erco and -aroj, -trov and -OTOV, 

 -ercoj/ and -arcav, -are (comp. irpocrtiirf), tiittiv, fiirwv ; from 

 the epic pres. eipco, fut. fpw, perf. eipr/Ka, perf. mid. or pass. 

 eipTjjuoi, fut. 3 fipT]o~ofj.ai. From PE aor. pass. fppijdr)v, pi)9?i- 

 vai, prjdeis, fut. pass. p^0r/(ro/tai. Middle (only in compounds), 

 fut. oTrepoOyUot, and aor. 1 airfiiraffBai, to doubt, to deny, as 



EXERCISE 131. GREEK-ENGLISH. 



1. Kai /3pa5vs fv&ov\os e*Ae TO.XVV affipa. Sitamav. 2. OlA.6riva.ioi 

 e/iKTTOJvAea ffTparriyov tl\ovro evTipTltpaiKip TroAeyUip. 3. OSt/o"- 



rai fj.r] ayavaKTti. 5. MTJ iricrrevf ra^icrTa, irpii/ arpeicfoos irepas 

 oi^ti. G. Mr/ TOUTO /3Ae>J>?7s, t vf&Tfpos \ey<a, aAA' ei (ppovovvrcnv 

 TOVS \oyous avSpcav epia. 7. ITe^flet /uerpiajs TOUS a-Troflai'oi'Tas 

 <pi\ovs ov yap TfBvrjKafftv, aAAa TI\V O.VTTJV ofiov, yv iraffiv f\df1v 

 tffTtv avayKri, irpof\7]\vBao"iv. 



EXERCISE 132. ENGLISH-GREEK. 



1. The Athenians took many soldiers. 2. The city chose Epa- 

 minondas general. 3. Themistocles was chosen general by the 

 Athenians. 4. Come, friend. 5. O dear friends, come hither. 



6. If thou art hungry, thou wilt eat with pleasure (riSeus). 7. 

 "^ho boy has eaten all he had. 



EY TO EXERCISES IN LESSONS IN GREEK. XLL, XLII. 

 EXERCISE 122. ENGLISH-GREEK. 



1. 'H (TTpaTia ffeTrXei/rreii. 2. 'H o-Tpana exjrXeuireiTai. 3. 'O axe.uor 

 'Boppar evavTio? T; tTTparto. irvet. 4. 'O ai/e/ior Boppar evavrtot rt] <rrpa.rto. 

 firvevafv. 5. Ol a-Tpariiarai i\\TU3av BfvffCffOai irpot Tar rri/Xat. 6. Tour 

 ari/xeif KXaicir. 7. Tow QTI/XET K\avaeit. 8. Oi TroXe^i/oi ^eufoBxrai. 9. 

 T\ai<rtv oLit\ttJv Tratfci. 10. AyotOot 7raioi>&iv u/ia trirovocL^ovTCy, 11. Ol 

 froXeufOi Td9 Ttoy ffTpaTiWTtoy Taffic <ry>x e * p(T ot | (7(i'. 12. *H TroXt? L/TTO TCOV 

 woXe/uiwi/ KaTaKtKauTai. 13. Ol <TTpaT(WTa< jj^ouvTai TOOT ?roX^iioOT rtjv 



EXERCISE 123. GREEK-ENGLISH. 



1. Many evil things have befallen the soldiers in the expedition. 2. 

 By associating, with wise men thou thyself also shale turn out wise. 

 3. Lycurgus banished costliness from Sparta. 4. Many who have 

 drunk together once will become friends. 5. The drunkard is the 

 slave of drink (lit., of having drunk). 6. I will not drink up wine. 



7. May the gods punish the evil-doers. 8. The citizens outstripped 

 the enemy iu their flight to the city. 9. The hare was bitten by 

 the dog. 10. You will not arrive nt the summit without toil. 11. 

 The women put on beautiful garments. 12. The wine was drunk up 

 .by the soldiers. 13. The friend promised to come to me. 



EXERCISE 124. ENGLISH-GREEK. 



1. *H fvvij r)MTeo-xTO KaXa i/aaria. 2. 'H yvvn afj.<pe^erai KaXa [fiarta. 

 3. Oi 0iXoi UTTctrxoi'TO a$ufec70a<. 4. 'O ffrparr)foy TOOT TroXe/itoir CfpOafftv 



fit TtlV KO\tV. 5. Ol 0601 TOOT KaKOUp'yOlT aTTOTlVOVfflV. 6. IIoXXoi 0lXoi 



av/j.irii>ov<Ttv. 7. "J'iXoi trvfj-irtvovTet e^Bpot ft-/voinai. 8. FloXXa xaxa Towr 

 <JUOOT 7rai5af avvtfinatv fv9aoe epxo/ii'OOT. 9. Toy KaKOfpyoi' fKftvov ATroXXui/ 



EXERCISE 125. GREEK-ENGLISH. 

 1. Let not the evil man think that he will escape notice for' ever. 



2. If you have done justly, you will have God as your ally. 3. It 

 is right to learn letters, and to have a learning mind. 4. The king 

 did not perceive the plot against himself. 5. The Persians were 

 hateful to the Greeks. 6. Philip himself used to declare that he 

 had increased his own realm more by the aid of gold than arms. 

 7. The soldiers slept a short time. 8. Directly the horses smelt 

 the camels they fled away. 9. Do not think that you have been 

 forgotten if you hare forsworn yourself to God. 10. It is good not 

 to err against one's friends. 11. He is happy who has gained a noble 

 friend. 



EXERCISE 126. ENGLISH-GREEK. 



1. 'O /Sao-tXeu? Tf|? Trpot tawrov 7ri/3oiXr]C aio-yaverui. 2. Ti? oi>x huaprriKev', 



3. OVK <7Ti irocjxav 6tf ev Tip aivTip a/uapTaifiv. 4. 'O woi'iipos TOit a-faDoit 

 O.Treyda.vTa.t. 5. floi/upo? it>v ov Xijo-eif oia TfXoOT. 6. Ol adc\<j>ot fLavQavovTes 

 fjidOovTOi vow CXOIXTII/. 7. Oi a^aOoi afaObJif Tei/fovTcu. 8. Oi avopes KUTC- 

 <5ap$or. 9. Bpaxuv xpovov KaTedapOov. 10. Tevvaiaiv <pi\wv TervxrjKa. 11. 

 SIui/0ciK0 aTi'x<ai< (pepetv. 12. KO.KOV fp"/ov trparriav e\a6cv. 13. EXn-ifovraj 

 \fjffeiv Trovnpoi OVT?. 



EXERCISE 127. GREEK-ENGLISH. 



1. You will find few men who are faithful companions in trouble. 2. 

 It is fated to all men to die. 3. We bewail the dead. 4. lien re- 

 member with pleasure ancient deeds. 5. You cannot find a man 

 who is completely happy in every respect. 6. The noble man 

 wishes to live honourably or die honourably. 7. If you have suf- 

 fered terrible things through your wickedness, do not at all blame the 

 gods for what thus befalls you (lit., for your fate of these things). 8. 

 If any one who is old prays for life, he deserves to live on into many 

 decades of years. 



EXERCISE 128. ENGLISH-GREEK. 



1. Ovbeva. t 

 CITTIV mrofave 



rov orpaTiiyow TOV Te$i'ijKOTa. 

 Ovoeio. travTa. oX/3ia>TaTov evpov 

 Ktvai. 8. IloXXa ireiaet 6ia 



pov iriinov ex x a X7roi? npainaatv euptjKa. 2. Zoi iJ.opaiiJ.ov 

 3. Tlevtfia TOV e/uoy Trarepa TOK Te#i/rjnoTa. 4. Hevti^iroi'<rtv 

 5. 'Hoewv TCOK TraXai fevvaiav p.ffjLvnU'i'. 6. 

 7. BouXo/iai f) KaXur fni/ r) xaXw? TeSvrf 

 aov iratpov. 9. Aui/aTOi/ <TTI TroXXa 



cfevpi(TKiv, aXX' ov Travra. 10. Ovoe oi a-sipot /3iov a\vtro 



PNEUMATICS. VII. 



COMMON PRESSURE-GAUGESAFETY TUBE ATMOSPHERIC 

 RAILWAY BLOWING MACHINES VENTILATION OF MINES. 



IN our last lesson we found that if a gas be kept under a uni- 

 form pressure, and heat applied, it will increase in bulk ^ of 

 its volume at for every degree the temperature is raised. 

 Suppose, now, that the gas be confined so that it cannot increase 

 in volume, we shall find that as the temperature increases the 

 elastic force will increase too, and in the same proportion as its 

 volume would were it free to expand. The rule may be stated 

 thus : 



If any gas be confined so that it cannot expand, and its 

 temperature be raised from 32 to 212", the elastic force will 

 be increased by 0'366 of its original amount. 



Sometimes the steam in an engine is exposed to a high tem- 

 perature after it is first evolved, and is then said to be super- 

 heated. Its tension is increased by this, and thus it can accom- 

 plish more work, and at the same time " priming," or the 

 condensation of the steam in the cylinders, is to a great extent 

 prevented. 



After what we have now seen respecting the change produced 

 in the volume of a gas by variations in the temperature or 

 pressure, we can very easily tell the specific gravity of a gas if 

 we know the weight of any volume of it, and also its tem- 

 perature and pressure. We have merely to ascertain the volume 

 it would occupy at the standard temperature and pressure, and 

 then compare its weight with that of the same volume of air. 

 In the same way we can calculate the weight of any volume of 

 gas, or the volume that a given weight of it would occupy. 



We described in our last lesson a manometer for measuring 

 high pressures like that produced in the boiler of an engine. 

 This acted by the elastic force of compressed air : a spring is 

 more commonly used, but it is somewhat liable to lose its elas- 

 ticity, or to become injured by the moisture of the steam. 

 These, however, only record high pressures, and not minor 

 changes like those produced by alterations of temperature. 

 We want, therefore, some means of measuring these, and for 

 this purpose we employ a U-shaped tube, open at each end. 

 The bend is filled with water if very low pressures are to be 

 measured, and with mercury if to be used for those rather 

 greater. 



If the gas whose tension is to be ascertained is allowed to 

 press on the liquid in one limb, it will depress it and raise that 

 in the other, and the difference in level between the two will 

 indicate the pressure. A sliding scale is usually attached to 

 show this difference. In this way we shall find that the pressure 

 of the gas, as usually supplied to our houses, is seldom equal 

 to two inches of water, a very small amount indeed when we 

 remember that the pressure of the air will sustain a column of 

 water over thirty feet high. It is, however, found to be quite 

 sufficient to overcome the resistance caused by the friction of 

 the gas against the pipes, and a greater pressure would only 

 cause a greatly increased loss by leakage from the mains. 



This pressure is produced by weights placed upon the gaso- 

 meter, and can in this way be regulated to a considerable 

 extent. It is found, however, that considerable variations 

 occur, it being greater just before the majority of people light 

 it in their houses, and again in large towns about eleven o'clock, 

 when many burners are turned off. These variations in pressure 

 cause a loss in illuminating power, and several regulators have 



