180 



THE POPULAR EDUCATOR. 



Currite ducentes subtemina, currite, fusi.] 



Nascetur vobis cxpers terroris Achilles, 

 Hostibua haud tergo, sed forti pectore notua : 340 

 Qui persjepe vago victor certamine cursus 

 Flammea prsevortet celeris vestigia cervse. 

 Currite ducentes subtemina, currite, fusi. 



Non illi quisqnam bello se conferet heros, 

 Quum Phrygii Teucro manabunt sanguine campi, 345 

 Troicaque obsidens longinquo mcenia bello 

 Perjuri Pelopis vastabit tertius heres. 

 Currite ducentes subtemina, currite, fusi. 



Illius egregias virtutes claraqae facta 

 Saepe fatebuntur gnatorum in funere Eiatres, 350 



Quum in cinerem canos solvent a vertice crines, 

 Putridaque infirmis variabunt pectora palmis. 

 Currite ducentes subtemina, currite, fusi. 



Namque velut densas prosternens messor aristas. 

 Sole sub ardenti flaventia demetit arva, 355 



Trojugenum infesto prosternet corpora ferro. 

 Currite ducentes subtemina, currite, fusi. 



Testis erit magnis virtutibus unda Scamandri, 

 Quoe passim rapido diffunditur Hellesponto : 

 Quoius iter cassis angustaus corporum acervis, 360 

 Alta tepefaciet permista flumina caede. 

 Currite ducentes subtemina, currite, fusi. 



Quare agite, optatos animi conjungite amores. 

 Accipiat conjux felici fcedere divam, 

 Dedatur cupido jamdudum nupta marito. 375 



Currite ducentea subtemina, currite, fusi. 



Non illam nutrix orienti luce revisens, 

 Hesterno collum poterit circumdare filo. 

 Currite ducentes subtemina, currite, fusi. 



Anxia nee mater discordis moesta puellu} 380 



Secubitu, caros mittet sperare ncpotcs. 

 Currite ducentea subtemina, currite, fusi. 



NOTES. 



337. Qualis adest, etc. concordia Thetidi. As the Jtarmony fJtat reigns 

 betveen Peleus and Thetis. 



338. Currite. After each set of four lines comes a sort of incanta- 

 tion by way of refrain EoH on, ye spindles of destiny, unwinding their 

 threads of life. So in Gray's " Bard " " Weave the warp and wind the 

 woof." 



339. Expers terroris, free from fear, dauntless. 



341. Victor certamine. His epithet in Homer is *-6<W tiw, th 

 swift-footed. 



342. Flarnmea, fiery, glowing, and so swift. Prsevortet, shall outstrip. 

 347 . Tertius heres. Agamemnon, third in. descent from Pelops, his 



father being Atreus, the son of Pelops. 



351. In cinerem. Shall shake their hoary locks from their heads into 

 the ashes. Putting ashes on the hair was in the East looked upon as a 

 token of grief. 



352. Ptitrida, pallid, liui'd. 



358. Scamandri was one of the rivers of the plains of Troy, and it 

 is frequently mentioned in Homer along with the Simois, another 

 Trojan river. Both of these are now small streams, generally half 

 dried up. 



359. Hellesponto. The Scamaudri fell into the Ionian Sea just at 

 the mouth of the Hellespont. 



360. Quoius, old form of cujus. Angustans, sc. Achilles, who is the 

 subject of tepefaciet in the next line. 



361. Permista caede, i.e., polluting it with the hot blood of the 

 warriors he had slain. 



TRANSLATION OP PAET OF EXTRACT I. IN LAST 

 READING. 



From the time when the winds tossed up the sea so high, and 

 Deucalion scaled the mountain in his ship, and asked for an answer 

 from heaven, and by degrees the stones grew soft and warm with life, 

 and Pyrrha displayed to the males the maidens in beauty unadorned 

 whatever men have done and are doing from that time to this their 

 prayers, their fears, their angers, their pleasures, and their joys are 

 the motley contents of our treatise. And at what time has there ever 

 been a finer crop of vices ? When has avarice been more greedy, or 

 the dice had such power ? For now they are not content to risk the 

 hazard of the gaming-table with their purse alone, hut they stake the 

 money- chest and play for it. What battles will you see there, while the 

 steward supplies the weapons ! Does it not show simple madness for 

 a, man to be content to lose a hundred sesterces, and not give back his 

 coat to the poor shivering slave ? 



HYDROSTATICS. Vrt I. 



WATER-CLOCKS HYDRAULIC MACHINES WATER WHEELS 

 BREAST WHEELS OVERSHOT WHEELS TURBINES 

 BARKER'S MILL. 



WHEN liquids have to be conveyed in pipes, care should be 

 taken to make the bends even and gradual, and in this way to 

 prevent the formation of eddies and currents. It should also 

 be remembered that there is a considerable amount of friction 

 between the liquid and the sides of the pipe, so that the portion 

 in the centre of the pipe flows more rapidly than that against 

 the sides. In the same way the velocity of a canal or river is 

 greater in the centre than at the sides. This friction increases 

 with the velocity at which the liquid moves, and also with the 

 area of the surfaces in contact. From all these causes the flow 

 of liquids through pipes is much less than theoretically it should 

 be, and hence in laying down pipes conaiderable allowance has 

 to be made for thia loss. 



In former times the flow of water was used as a means of 

 measuring time, the apparatus constructed for this purpose 

 being called a clepsydra, or water-clock. The water is allowed 

 to flow from a jet into a reservoir below, in which is a float rising 

 with the water and carrying at the top a pointer. The reser- 

 voir is made of the same size throughout, so that the addition 

 of equal quantities of water causes equal rises in its surface. 

 The water is allowed to flow in for a given time say, half an 

 hour and the rise noted ; marks are then made at this distance 

 apart, and by these the time may be told. As, however, the 

 rate of flow depends upon the pressure, it is necessary in such 

 an apparatus to maintain the same head of water in the 

 upper cistern, and this may be accomplished in the way men- 

 tioned in our last lesson, by letting the water constantly over- 

 flow the vessel. 



There are, however, better ways of accomplishing this, which 

 are frequently used. In the boiler of a steam-engine, and other 

 machines, it is frequently very important thus to maintain a 

 constant level, and this ia attained by means of a ball-cock or 

 float. A block of wood, or hollow ball of metal, floats on the 

 liquid ; this block is either fixed on to a lever or fastened to a 

 cord, so that when the level of the water becomes lower, and 

 the float descends, it opens a valve or turns a tap, and allows 

 the water to enter till the level is restored. 



We will now look at the most common hydraulic machines, 

 and examine their construction, and the principles on which they 

 act. The simplest division is into three classes, the first em- 

 bracing those whose object is to employ the force of falling 

 water as a prime mover ; the second, those which are intended 

 to raise water to any required elevation ; while the third 

 contains those which are used to propel vessels through 

 the water, and other machines not included in the previous 

 classes. 



In many districts, especially mountainous ones, there exist 

 many waterfalls and rapid streams. In these there is a largo 

 amount of motive power, which is frequently utilised in giving 

 motion to the machinery employed in mining and other opera- 

 tions. This power would be much more employed than it is 

 were it not that sometimes, from long-continued droughts, 

 the body of water is much diminished. If we take any two 

 points in a stream, we shall find that the one higher up the 

 stream has a greater elevation than the other, and the power 

 capable of being exerted by the stream between these points is 

 equal to the power of the body of water there is in the stream 

 'ailing vertically through this distance. If the stream dis- 

 charge 1,000 gallons per minute, and the difference in height 

 Detween the two points be four feet, the power stored up 

 n the water is 1,000 x 10 x 4, or 40,000 foot-pounds per 

 minute, but even in the best machines a large portion of this 

 is lost. 



When we want to ascertain the force of a stream, we have 

 irst to find the sectional area. This may be done by taking 

 ;he depth at intervala of five or six feet from bank to bank, the 

 average of these being the mean depth ; multiply this by the 

 >readth, and we shall have the area. We must then proceed to 

 ind the average velocity, but as the stream flows more rapidly 

 n the middle than at the side, it is rather difficult to ascertain 

 this accurately. An instrument, consisting of several fans, 



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