would burst open the end of the pipe were it not for the valve st F. This provides an escape, and the water opens it, and causes a certain amount to enter the reservoir, compressing the air contained in it, and thereby forcing a fresh amount of water up the tube B.

The compressed air, however, acts as a spring, and thus the momentum of the column of water is soon destroyed, F then closes of its own weight, and the water in the tube being now at rest, c again opens and allows the water to escape as at first. When the weight at c is carefully adjusted this opening and closing succeed one another rapidly, producing a series of stoppages, by each of which a small quantity of water is raised in the pipe B.

A larger amount, however, escapes at c than ascends in B, and the amount raised diminishes, of course, with the height to which it is raised; still it is calculated that about 60 per cent. of the power of the water may be utilised by the arrangement, which certainly by its ingenuity reflects great credit on the inventor.

Occasionally, in mines, a stream of water is caused to move an engine, constructed on exactly the same principle as the steamengine, the motive power being the pressure of the water instead of the pressure of steam. By an arrangement of valves the water

which have not yet been explained; but it is best to consider all together, as in this way we can better understand their differences in construction.

First, then, we notice those which act mechanically. The plan of raising water by means of a single bucket would naturally suggest the idea of fixing several one below the other, and thus an endless chain of buckets passing over a wheel at the top was constructed.

is made to press alternately on the upper and lower sides of the piston, and the motion thus produced is by means of a crank and fly-wheel communicated to the machinery.

We have thus noticed all the most important machines designed to derive motion from a fall of water, and now pass on to the second class, or those which are intended to raise water to any required elevation.

after

Water is one of the prime necessaries of life, and as its tendency is always to sink to the lowest level, various plans of raising it have been tried from the very earliest ages. The mest primitive is by means of a bucket fastened to a rope; a time, it was found more convenient, when the height to which the water had to be raised was not great, to fix this rope to one end of a lever supported near the middle on crossed poles, and pull by means of a rope fastened to the other and shorter end. A further improvement on this, which is a the present day much used on the banks of the Nile, consisted in fixing a weight at the other end of the lever, so as nearly to balance the bucket of water; a man then alternately raises and lowers it by pulling the rope. Much of the land in Egypt is irrigated by this contrivance, which is known as the Shadoof.

The buckets are brought up full, and when they reach the wheel strike against a support, and being turned over discharge their contents into a channel prepared to receive them. The wheel in this case may be turned by the foot, as is frequently done, or the power of animals may be employed.

The next modification of this arrangement is what is known as the Persian Wheel, which is represented in Fig. 31. Floats are fixed to one side of an undershot or tidal wheel, and in the other side of the rim are fixed a number of pegs, from which buckets are suspended. As the wheel is turned by the force of the current, these successively dip into the water, and are brought up nearly full. The weight of their contents keeps them in a vertical position till they reach the top, where they strike against trough, and thus are emptied into

a

it. The water is conveyed from this by a channel not shown in the figure. By this plan the water cannot well be lifted to any great height, as the diameter of the wheel must be greater than the height. This machine can be used in a tidal river, as it will work in either direction.

A further supply of water is, in this wheel, raised to the level of the axis on a totally different principle. The spokes of the wheel, instead of being made straight, as is the case in ordinary wheels, are hollow and curve considerably. Openings will be perceived on the rim, by which the water enters when they are

The common windlass is used instead of this where the water has to be raised from a great depth; as, however, there are a large number of machines in use, it will be best to make a simple division of them, and perhaps the simplest we can make is the following:

1. Those which act mechanically;

2. Those which act by the pressure of the air; 3. Those which act by centrifugal force. The second of these divisions contains the common pump and similar machines, which, strictly, ought not to be explained till we come to treat of pneumatics, as they involve principles

immersed, and from the shape

of the spokes it cannot flow out again, since the openings are higher than the bends. The water, therefore, travels along them towards the axis, and there is discharged into a trough prepared for it.

Another very ingenious and elegant machine, acting on the same principle as the spokes in the Persian wheel, was invented by the celebrated philosopher Archimedes, and is called after him the Archimedian Screw (Fig. 32). It consists of an inclined axis, which may be turned by a winch. One end of this is in the stream or reservoir from which the water has to be raised, and the other over the reservoir into which it is required to flow.

A tube or pipe is twisted spirally round this axle, the angle at which it is twisted being so arranged that as it is turned by the handle the water constantly flows towards the upper end. A glance at the illustration will show that the portions of the spiral on the side shown all incline to the right, so that the water in them flows in that direction. When used in practice, instead of a tube being twisted in this way, a spiral flange, like the thread of a screw, but projecting to a much greater distance, is fixed on the axis and made to turn inside a straight tube which it just fits.

In this way there is much less friction of the water, and a

larger amount can be raised than when a twisted pipe is used. A working model of this screw can, with a little ingenuity, be easily constructed with a piece of flexible pipe.

There is another machine, known as the tympan, which is sometimes used to raise water, and acts on the same principle, though constructed differently. A hollow drum is made to turn on a horizontal axis, motion being imparted to it by a wheel working in the cogs round its edge. This drum is divided into compartments by means of partitions curved in a similar way to the spokes of the Persian wheel, and as it rotates the water enters these compartments, and is emptied at the axle into channels made to receive it. This, however, can only be used with advantage when the water is not required to be raised to a great height.

EXERCISE 57.-GREEK-ENGLISH.

1. Ο βαθύτατος ύπνος ἥδιστος εστιν. 2. Πολλα ανθη ἡδιστην οσμην παρέχεται. 3. Ουδεν θαττον εστι της ήβης. 4. Την αισχίστην δουλειαν οἱ ακρατεις δουλευουσιν. 5. Παντων ἡδιστον εστιν ἡ φιλια. 6. Ουδεν αισχιον εστιν η αλλο μεν εν νῳ εχειν, άλλο δε λεγειν (to think one thing and say another). 7. οἱ οφεις τοις λοιποις ζώοις εχθιστοι εισιν. 8. Ουδεν τῳ ανθρωπῳ εχθιον εστιν η δ ανθρωπος. 9. Ταχιστα ὁ καιρος μεταφέρει τα πραγματα.

EXERCISE 58.-ENGLISH-GREEK.

1. Nothing is sweeter than deep sleep. 2. Sleep is very sweet. 3. Nothing is more disgraceful than slavery. 4. Slavery is a very bitter thing. 5. Horses are very swift. 6. Nothing is more hostile (unfriendly) than bad advice. 7. It is shamefu to think one thing and say another. 8. Bad men think one thing and say another. 9. Nothing is sweeter than a faithful friend.

7. ολιγος, few 8. μέγας, great 9. πολυς, much 10. ραδιος, easy 11. πεπων, ripe 12. πιων, Several adjectives which express the idea of order or succession appear in the comparative and superlative only, since from their import they cannot denote an absolute quality, and may be used only in comparison. Their root will be found in a preposition, or adverb of place; for example

ADJECTIVES WITHOUT A POSITIVE.

From προ, before, From avw, up, From ύπερ, over, From ύπο, under, From εξ, from,

From πλησιον, near, in πλησιαίτερος,nearer, πλησιαίτατος, Homer πλησιος, est.

near

From προσω, forwards, προσώτερος, further, προσωτατος, furthest. more in advance, VOCABULARY.

Αναγκαιος, -α,

necessary. Αναγκη, ης, ή, neces. sity. Αναρχία,

-as,

ή,

absence of govern. ment, anarchy. Γείτων, ονος, ο, ε neighbour.

Ισχύω, I am strong. | Κελεύω, I order.

Μαλακος, -η, -oy, soft. Μετρον, -ου, το, mea sure, moderation. Σκωπτω, I jeer. Στεργω, I love, I am satisfied with, put up with. Συμβουλος, -ου, ὁ, απ advisor.

Ελεύθερος, -α, -ον, Κολακεία, -as, ή, Σωφροσύνη, της, ή, free.

flattery.

sound-mindedness.

'Os, with a superlative, adds strength to it, as quàm in Latin: for example, ὡς τάχιστος, quam celerrimus, as swift as possible. EXERCISE 59.-GREEK-ENGLISH.

1. Ουχ ὁ μακροτατος βιος αριστος εστιν, αλλα δ σπουδαιότατος. 2. Μετρον επι πασιν αριστον (understand εστιν). 3. Γνωμαι των γεραιτερων αμείνους εισιν. 4. Συμβουλος ουδείς εστι βελτιών χρόνου. 5. Η λεγε σιγής κρειττονα, η σιγην εχε. 6. Αει κρατιστον εστι το ασφαλεστατον. 7. Σκώπτεις, ο λωστε. 8. Βελτιόνων κακίους ενιοτε ευτυχέστεροι εισιν. 9. Ουκ εστι λύπης χειρον ανθρωπῳ κακον.

αναγκης.

10. Κολακεια των αλλων απαντων κακών

χειριστον εστιν. 11. Ανηρ μαλακος την ψυχην (as to his sou!, mind) και (even) χρημάτων ήττων. 12. Ταις γυναιξιν ἡ σωφροσυνη καλλιστη αρετή εστιν. 13. Ουκ εστι κτημα καλλιον φίλον. 14. Η δουλεια τῳ ελευθερῳ αλγιστη εστιν. 15. Η οδος μηκιστη εστιν. 16. Ο κροκοδειλος εξ ελαχιστου γίγνεται μέγιστος. 17. 'H ελαττων εστι του ήλιου. 18. Στεργε και τα μειω. 19. Ολίγιστος 20. Ούδεις νομος ισχύει μείζον της ανθρωποι ευδαίμονες εισιν. 99 22. 21. Μικρα κερδη πολλακις μείζονας βλαβας φερει. Αναρχίας μειζον ουκ εστι κακον. 23. Ο πόλεμος πλειστε κακα φερει. 24. Έμφυτος εστι τοις ανθρωποις ἡ του πλειονος επιθυμία. 25. Γυνη εσθλη πλειστα αγαθα τῷ οἴκῳ φερει. 26. Τα αναγκαία του βίου φερε ὡς ῥαστα (as easily as you can). 27. Το κελεύειν ῥᾳον εστι του πράττειν. 28. Οἱ της σοφής καρποι πεπαίτατοι εισι. 29. Εν τῳ του πατρος κηπῳ οἱ της αμπελου βοτρυες πεπαίτεροι εισιν, η εν τῳ του γειτονος. 30. Ιβηρια τρεφει πιοτατα προβατα. EXERCISE 60.-ENGLISH-GREEK.

1. There is nothing better than a very diligent life. 2. The opinion of the ancients is very good. 3. Time is the best adviser. 4. The safest is the best. 5. Grief is a very great evil. 6. Nothing is worse than flattery. 7. The intemperate man is the slave of pleasures. 8. Women have nothing more beautiful than wisdom. 9. To a free man nothing is worse than slavery. 10. The crocodile is very long. 11. The son is less than the father. 12. The bad often have more property than the good. 13. War brings very great evils. 14. It is easy to command, it is hard to obey. 15. We enjoy most (superlative neut. of ἡδυς) the ripest fruits. 16. My father's sheep are fatter than those of (the article Ta) his neighbour.

GENERAL VIEW OF THE TERMINATION OF ADJECTIVES.

In order to assist you in mastering the subject, I here put together the different terminations of adjectives. I add those of the participles, because the participle and the adjective are declined alike; remember that both adjective and participle are also declined like nouns of the same terminations. You will also call to mind that adjectives are divided into three classes: 1, those of three terminations; 2, those of two terminations; 3, those of one termination.

1. ADJECTIVES OF THREE TERMINATIONS.

αγαθα.

Gen.

Gen.

άρρενος.

Nom. ογδοος,

G. Plu. ογδόων, ογδόων,

ογδόων.

Gen.

απάτορος.

Nom. γραφομενος, γραφόμενη, γραφομενον, written. G. Plu. γραφομένων, γραφομένων, γραφομένων.

KEY TO EXERCISES IN LESSONS IN GREEK.-XVI. EXERCISE 53.-GREEK-ENGLISH.

1. Aristides was very poor, but very just. 2. The Cyclops were most violent. 3. Callias was the richest of Athenians. 4. Nothing i3 more serviceable than silence. 5. Silence at times is preferable to speech. 6. Nothing is more honourable than wisdom. 7. Wisdom is a possession more honourable than wealth. 8. The Spartans' mode of living was the most simple. 9. The more aged exult in the honours of the young. 10. Fatherland is very dear to mankind. 11. The Indians are reckoned a very ancient race. 12. Ο children, be very quiet. 13. The Spartan young men were stronger than those of the Athenians. 14. Many are more garrulous than swallows. 15. Slaves are often very mendacious and very thievish.

EXERCISE 54.-ENGLISH-GREEK.

1. Ο πατήρ εστι σοφώτερος η ο υἱος. 2. Η μητηρ εστιν λαλιστερα η ἡ θυγατηρ. 3. Η αρετη εστι τιμιώτατον κτημα. 4. Σωκράτης την σοφώτατος των Αθηναίων. 5. Οἱ Αθηναίοι ήσαν σοφωτεροι η οι Λακεδαίμονες. 6. Ουδείς των παλαιών Ελληνων σοφωτέρος η Αριστείδης. 7. Ανδρες εισιν ἡσυχαιτεροι των παιδων. 8. Οι Λακεδαιμονες ήσαν ισχυρότατοι. 9. Αἱ χελιδόνες εισι λαλιστεραι. 10. Ο κόραξ εστι κλεπτίστατος. 11. Η διαιτα του Σωκράτους ην απλουστατη. EXERCISE 55.-GREEK-ENGLISH.

1. Youth passes by as suddenly as thought, nor is the impetuosity of horses more swift. 2. Old age is heavier than Etna. 3. Death is most like a very deep sleep. 4. Young men rejoice in the praises of old men. 5. The possession of a just friendship is very safe. 6. The mean in all things is safest. 7. Old men are weaker than young. 8. Nothing is safer than right counsel. 10. Socrates was 9. Crows are very black. most continent and temperate. 11. In misfortune men are more prudent 12. Critias was most rapacious. 13. Aphrodite than in good fortune. was the most graceful (or pleasant) of all the goddesses.

1. Το γήρας βαρύτατον εστι 2. Ουδέν εστι ωκυτερον του νοήματος.

EXERCISE 56.-ENGLISH-GREEK.

3.

Η μεσότης εστιν ασφιλέστατη. 4. Ουδεμία ορνις μελαντέρα του κορακος. 5. Ο παίς εστιν ωκυς, ο ανηρ ωκυτερος, ὁ δε ίππος ωκυτατος. ευχαριστερα η το γηρας. 7. Οἱ Αιθιοπές εισι μελάντατοι,

6. Ηβη εστιν

8. Ουδείς των

ανδρος, 10. Ουδεν εστι των καλών ανθέων ευχαριστερον.