« ΠροηγούμενηΣυνέχεια »
(our) father. 17. Thou well contendest with thyself. 18. God is with | Anson's crew had been provided with fresh vegetables to eat thee. 19. Often the mind is in discord (disagrees with itself). 20. their scurvy would have been cured; and they knew it. How The enemies fight earnestly with us. 21. Thy speech is not in unison
great, then, must have been the fear of the surgeon, and how with thyself.
valuable is the knowledge of Botany! EXERCISE 52.- ENGLISH-LATIN.
Returning to our investigation of the distinctive signs by 1. Omnia mea mecum porto. 2. Secumne omnia sua portant sa
which cruciferous plants may be known, we shall merely cal pientes? 3. Tu me amas, ego te amo. 4. Vita tua mihi est cara,
your attention to the fact that each flower has six stamens, of mea tibi. 5. Mali semper secum discordant. 6. Tractatio literarum
which two are more spreading and shorter than the others ; gratissima est nobis. 7. Amant sese homines. 8. Amantne sese mulieres? 9. Pessime amant sese mali. 10. Per se pulchra est virtus.
hence the denomination Tetradyna11. Propter te ipsum te amo. 12. Mea patria gratior est mihi quam
mia (or four-powered) in the Lintua tibi,
næan or artificial classification, and
| this is another essential character. LESSONS IN BOTANY.-XV.
istic of cruciferous plants. The
other characteristic signs being for SECTION XXVII.-CRUCIFERÆ OR BRASSICACEÆ, THE the most part microscopic, we pass
CRUCIFEROUS (OROSS-BEARING) OR CABBAGE TRIBE. them over without notice. ALREADY, in an early lesson, we have had occasion to make a The Cruciferoe are dispersed all statement respecting the cross-bearing flowers that we hope the over the surface of the globe; the reader has not forgotten. We mentioned that a strange plant greater number, however, inhabit being referred to this natural order, such plant might at once the northern temperate zone, more be considered harmless, and probably very good to eat.
especially of the Old World; beLet us now go a little more minutely into the characteristics tween the tropics they are rare, and of these cross-bearers. They are these : Sepals, four, free; / when they exist, are found on mounpetals, hypogynous, four, free, cruciform; stamens, six, tetra
tain elevations; beyond the Tropio dynamons; ovary, bilocular, placenta parietal; fruit, ordinarily a
of Capricorn they become less fre. 147. FLOWER OF THE STEPpod; seed, dicotyledonous.
quent, even more so than beyond HERD'S PURSE, ENLARGED. Let us now proceed to the application of such of the pre
plication of such of the pre. | the Tropic of Cancer. ceding characters as may be necessary. Firstly, the propriety
When we mention that cabbages, sea-kale, mustard, cress, of the term cruciferous will be rendered evident from an exami. and radishes belong to this order, we shall have stated enough nation of the representation of the flower of a plant termed to demonstrate the utility of its species. When we state again Shepherd's Purse, one of the cruciferous family (Fig. 147). that wall-flowers (Fig. 149) and stocks are cruciferous plants,
This same individual, the Shepherd's Purse, shall also serve the reader will see that utility is not the only claim which to teach us yet something more regarding the peculiarities of the Cruciferæ present to our notice. the natural order Crucifero.
The Crucifere are imbued with an acrid volatile principle disLet us now examine a branch of the plant (Fig. 146).
persed throughout all their parts, and frequently allied with Directing our attention at first to the flowers, we find them sulphur. To this volatile principle cruciferons plants owe their to be arranged after the manner of a raceme, and totally devoid piquancy and their peculiar odour, which, after putrefaction, is of bracts. This absence of bracts pervades the whole natural ammoniacal; thus proving the Cruciferæ to contain the simple order Crucifere, which is the only natural order in which the body, nitrogen, ammonia being a compound of nitrogen with bracts are uniformly absent. Hence by this sign a cruciferous hydrogen. In many species of Cruciferæ there exists in convegetable may be as readily known as by the structure of the nection with the odorous principle also a bitter material and a flower ; indeed, the sign of absence of bracts has a wider sphere fixed oil ; the latter is chiefly developed in the seed. The active of application. The flowers of the Cruciferæ are at the best principles of annuals belonging to this order reside in the very small, but perhaps they might not yet have fully developed leaves, those of the perennials in the root. Certain species, the themselves at the period of observation. Consequently, if the leaves of which are inoperative, produce very acrid seeds. Many cruciferous shape of flowers were the only guide, the student Cruciferæ grow mild by cultivation, which augments their might not be able to wait for the sign of discrimination; amount of sugar and mucilage. The anti-scorbutic properties whereas by noticing the absence of bracts, he would know the of many Cruciferæ have been known from times of great
plant under consideration to be antiquity; the species which possesses the greatest fame in this
withstanding the scurvy was mak-tubular, urceolate (like a pitcher, from the Latin urceus, 146. SHEPHERD'S PURSE. ing great ravages amongst them. pitcher), ordinarily furnished at its throat with one or more
Now the reader must be informed, series of filaments. Stamens sometimes inserted upon the if he does not already know, that the scurvy is a disease throat of the perianth, or upon its base; sometimes hypogynous, almost entirely dependent upon too exclusive a diet of salt meat, attached to the support of the ovary ; ordinarily equal in number without accompaniment of vegetables, more especially vegetables to that of the external divisions of the perianth. Orary stipu. of succulent character. Formerly the scurvy made great ravages late; three or five placentæ; three or four styles terminated by in our navy; at present it is scarcely known, having been club-like stigmas ; ovules reflexed; fruit, a berry, indehiscent banished, partly by the administration of fresh preserved pro- (not splitting), or capsular, three or five valved ; seed, dicotyle visions, but chiefly by the administration of lime-juice, which donous ; embryo straight, central.
constitutes a portion of the rations of every sailor. If We shall be able to individualise the Passion-flower order without giving ourselves the trouble to appeal to all the charac- Passion-flowers. The term petaloid means resembling a petal ; teristics mentioned. Nevertheless, botanists who penetrate more the termination oid being derived from the Greek word Eldos deeply into the study of plants, find it necessary to appeal to all (ei-dos), likeness, which word, in composition, changes eid into the characteristics mentioned.
oid. Directing the eye to the lower part of the sepals, they Many species of Passion-flower are now common enough in will be observed to rise from a shallow cup-like body, to which our gardens. For the purpose of examination we shall select also are attached the petals and other portions of the flower. an individual
As regards of the species
the petals termed Ama.
themselves, bilis, the repre
they are cosentation of
loured simiwhich we sub
larly to the join (Fig. 152).
colour of the The student
inside of the will first ob
sepals, and are serve,on glanc
of the same ing at the
colour on both broad charac
sides, by which teristics of the
circumstance specimen, that
they may be the flower is
distinguished supplied with
from the se three large
pals, as also bracts, which
by the circumconstitute
stance of their what botanists
not having & term an invo.
little born, Lucrum. Pro
which may be ceeding in
found on ex Fard, we next
amination arrive at
springing from what? The
each of the secalyx? It
pals. should be the
We next arcalys, judging
rive at the filafrom its posi.
mentary rays tion, but the
which the appearance of
imaginative its separate
Spaniards parts (sepals)
compared to is different
the crown of from the ap
thorns! What pearance of
are those raya? those sepals
Theyare petals we have al.
so modified in ready met
shape that with. They
they almost are not green,
present the but coloured
appearance of like the petals
stamens. This of mostflowers.
modification, We have al.
and yet more ready stated,
frequently its however, that
converse, staamongst the
mens modified other trans.
into petals, is formations of
not at all un parts which oc
frequent in casionally en
many flowers, sue, the trans.
as the result formation of
of cultivation. the calys into
In the Passiontheappearance
flower tribe, of a corolla is 150
however, it not unfre.
exists as the quent. So fre. 148. SCURVY GRASS (COCHLEARIA OFFICINALIS). 149. THE WALL-FLOWER. 150. TRANSVERSE SECTION OF OVARY usual condiquently, in- OF PASSION-FLOWER. 151. OVARY OF PASSION-FLOWER. 152. SCARLET PASSION-FLOWER (PASSIFLORA AMABILIS). tion of the deed, does this
flower. Let occur, that mere green colour is not to be regarded as more / us now proceed to examine the reproductive, or fruit and seedthan a collateral circumstance. The external floral whorl is producing portions of the flower, which are very peculiar. We always considered by botanists as a calyx, whatever its colour have already mentioned a cup-like body in connection with the may be. That colour is often very brilliant, as in the fuchsia, structure of a Passion-flower. It corresponds with the part for example, where the gay-looking part of the flower is not lettered c in Fig. 151. In the centre of this cup a column-like corolla or aggregation of petals, but calyx, or aggregation of body is observed rising aloft in the centre of the flower, to which sepals. This assumption by the parts of the calyx of the certain appendages are attached. The nature of these appendages appearances usually presented by the corolla gives rise to what will at once be obvious. Externally, we easily recognise five botanists term a petaloid perianth. The student will find this anthers, and internally we recognise the club-headed pistils; but term comprehended in the list of characteristics peculiar to looking again at the stamens, we search in vain for the filaments
to which they are usually attached. These smeta do poterit sirsady been given. He ransacked the abbeys and other depo. sat least do not separately exist; they are al auto- iss Ekze teocris for proof of his right, and though he found ube French say, and it is a very good wori-o te p o se e congement by so doing, he none the loss boldly
Tary This expression, “support of the ctary," is net to us; Liribed bes pretensions. In answer to the reference made to Dat if the reader looks at his dissect P G - Ter, or at E s rederee, he directed the claimants to meet him at davram in Fig. 151, he will recoguise te perdity of the Soba, Testber he marched with a large force, which was Expression : for in this tribe the orary 25 GRTAT 10 Dect to Terawe the Scotch Parliament or Council, assembled flower by means of a little strm. Now the
be st teame place called a stipes, the ovary is said to be state. Tuis is the I» Vay, 1291, the meeting took place accordingly at Norham, roader will remember, occurs in our E-t of characterists of the Scots beieg drawn up in a green plain opposite the castle, this natural order. Let the student ac* enize aith wore
oszce of the demand they made to be allowed to deli. in detail the anthers or pollen-forumz bura is of the Deze berate in their own country; the English king and his followers These do not point towards the stones, in the opposite ber stationed on the English side of the Tweed. To the direction, which is very unusual. Fertist of the ove! Sr e cap went the English Lord-Chancellor Burnel, and depends, as we need not repeat, upon contact betrec te seked is bs master's name “ whether they would say anything pollen-dust and the stigmas; hence it w i e est de tbst oca or caght to exclude the King of England from the anthers shonld always point towards the sti . is met rigt: ad exercise of the superiority and direct dominion over cases they do so point towards them, but in tua Pascun-cret the tezdom of Scotland, which belonged to him, and that they tribe we find an exception to this rule.
tood there and then exhibit it if they believed it was expediens Fig. 150 represents the transverse serting of the OTSIT ea for teen;protesting that he would favourably hear them, taining the seeds. The fruit, or ripened orary, in each what is just, or report what was said to the king and the Passion-flower is egg.shaped, differing in size 2 2 beta ocasecl that what justice required might be done." No species. The blue Passion-flower prices , fratshs th: dianat voice having been raised, a notary who was present size of a hen's egg; but in other species the fruit is nach langer, fotoy registered the right of the King of England to decide and contains a delicious palp.
the coatroversy as to the Scottish crown; and then the chanPassion-flowers, we have seen, are both agreesble sed teen olor in zired of all the competitors, beginning with Robert from the beauty of their flowers and the flavour of the fruts; Bruce, "whether, in demanding his right, he would answer and many species are medicinal. The pulp sutan ting their seeds receive justice from the King of England as superior and direct is in some cases sweet, in others acid; the latest serve as the end over the kingdom of Scotland." Bruce answered," that he basis for the preparation of acidulated drinks, not only agndable . acknowledge the King of England as superior and direct but medicinal. One species, Passiflora Ruóra, contains a mar loal of the kingdom of Scotland, and that he would before cotic principle which is sometimes employed as a substitute for him as such, demand, answer, and receive justice." In like opium. Passiflora Quadrangularis is cultivated for the nefnshing words the other claimants answered the chancellor's question, palp surrounding its seeds, but its root is very poisonous. In and side and sealed a solemn instrument to the same effect. European gardens a large number of species of the Passion-tiower Commissioners were then appointed to represent the competitors, are now cultivated, amongst which may be cited as the chief, and sittings were held forth with at Berwick, where the whole Passiflora Cærulea, or the blue Passion-flower; ta is being the matter was solemnly gone into. commonest of all. Of this flower the Passio e Auri's (Fig. Judgment was given in favour of John Baliol, who was ready 152) is a hybrid or cross race between Passiflora 4ta and to acknowledge himself the vassal of the English king ; but the Passiflora Princeps. Its flowers are scarlet, and exhale a deli. Scottish lords of parliament, who attended the conference, cato odour. The Murucuja Ocellata is a hot-house species, expressly declined to do this, saying that they would not answer bearing deep-red flowers. Tactonio Mollisima bears rose- such a question until they had a king, at the same time coloured flowers, and is a climbing plant, requiring a green. ' rernin ling the English that the claim once recognised under house for its culture.
daress had been expressly and solemnly renounced, and that on
several occasions their kings had refused to lend the help HISTORIC SKETCHES.-XV.
which as feudatories of English honours they really owed,
unless their independence so far as Scotland was concerned HOW ENGLAND AND SCOTLAND BECAME ONE.-PART II. was formally and distinctly recognised. Eventually, however, MANY competitors, as might be supposed, appeared to contest their unwillingness was overcome; they swore fealty to Edward so great a prize as the crown of Scotland; but the question really, as lord paramount, and acquiesced in the surrender of the lay between two, John Baliol and Robert Bruce, noblemen of principal Scotch fortresses into his hands. English dominatic 1 Norman extraction. The ground on which they founded their was complete, and to show that it was so, King John was sir respective claims to the Scottish throne was as follows: William ' times summoned to the English Parliament as one of the vassal the Lion died, leaving a brother David, who was created Earl of peers. Huntingdon on his marriage with King Edward's sister. This Even Baliol, indolent and wanting in self-reliance as he was reearl had three daughters: the first, Margaret, who married Alan, belled at this, and the Scotch people, chafing under the idea of Lord of Galloway ; the second, Isabella, who married Robert being in bondage, resolved to back him on the first opportunity Bruce, of Annandale; the third, Adama, who married Lord that he should attempt to throw off the English yoke. This oppor Hastings. At the time of the death of Alexander III., John tunity presented itself in 1294, when war broke ont between Baliol, the grandson of Margaret, Lady Galloway, claimed the France and England. That war had raged for some time with Crown, a. nearest descendant of the elder branch; and Robert varying success, when in 1296 Edward called on John to help him Brosa claimed it try what he asserted to be a better title, in against France, and to surrender certain strongholds as security that he was the son of Isabella, the second daughter of David, for his doing so. John refused both demands, and Edwar. * w *174 one generation nearer to the original stock. Lord immediately marched with a strong army to the north, glad of liana maimed, somewhat absurdly, a third of the kingdom, the pretext he had long sought of bringing Scotland under om the UTET in that it must be divided equally between the own personal sway by conquest. At Berwick and Dunbar we three branches, as private property might have been. The last Soots were beaten with dreadful slaughter, after which Stirling, claim was never wriously entertained by any one ; but though Edinburgh, Roxburgh, and all the southern part of the king modern law and custom would have found no diffioulty in dom, fell into Edward's hands. Bruce and his son, with many deciding in favour of John Baliol, the question between him more of the Scotch nobles, were in the English camp, the and Bruce was, in the then state of law, by no means an easy unhappy country was divided against itself, and it fell with a one to answer. Both claimants determined to support their great fall. Everywhere submission was made to the conqueror, pretensions by force of arms, and were gathering their friends the hare-hearted Baliol resigned his crown to Edward, who for that pomose, when they were persuaded to refer their dis. returned to the south undisputed lord of the whole of Great ation of the King of England.
Britain. Baliol was imprisoned and afterwards died in banishhis opportunity, and resolved to seize it. ment, and Earl Warenne was appointed viceroy or lieutenant of decide the matter by virtue of his being Scotland. otland, a dignity the value of which has ! For eighteen months things went on drearily in Scotland;
the people lacked leaders ; those who should have led them were In 1305-6, however, Robert Bruce, Earl of Carrick, grandson afraid, incapable, or actually on the enemy's side; the iron of the competitor of Baliol, and one of those to whom Edward heel of English dominion pressed heavily on the land, and chiefly looked to secure his Scotch conquests for him, awoke to entered into its soul. But there was a secret determination to a sense of his duty, and entered into a plot for the overthrow of make use of the first opportunity for throwing off the oppressor's the Anglo-Scotch tyranny. Accident suddenly compelled him yoke. Men bided their time, nursing up their wrath against to declare himself, and when he did so as the would-be libethe day of slaughter, waiting as patiently as they might for rator of the kingdom and claimant of the crown, he was their natural leaders to come to their aid. At the end of promptly joined by many of those “wha hae wi' Wallace bled.” eighteen months the opportunity came. King Edward was The principal Scotch nobles espoused his cause, and so strong absent with his army in Flanders, and Earl Warenne was did Bruce find himself that in March, 1306, he caused himself obliged by ill health to leave Scotland. The strong men were to be crowned king at Scone, the ancient coronation-place of away, and the tyrannical conduct of the under rulers, especially the Scottish kings. that of Cressingham and Ormesby, served to irritate the Scots Overwhelming were the preparations made by Edward to into taking advantage of the circumstance.
crush the rebellion, as he called it. The Earl of Pembroke and In the mountains and forests there had lived ever since the other commanders invaded the country, and defeated Bruce and English came a number of so-called outlaws--men of inde- his friends in many encounters; so that by the winter of 1306 pendent spirit, trained to rough life, and imbued with the many of the chiefs were taken and executed, and Bruce himself Freedom of the air they breathed-men who never would acknow. was a wanderer. Bloody was the vengeance taken by Edward ; ledge the English rule. Chief of them was William Wallace, a the nearest and dearest of the principal actors in the field were man of whom probably his friends have said too much, as his cruelly put to death, and every circumstance of indignity was enemies undoubtedly have said more than enough; a rough made to accompany their punishment. Nevertheless, in the soldier, in whose breast the unrefined spirit of liberty had a spring of 1307, Bruce with a small band of followers appeared home, and who acted both according to his roughness and in Arran, and, passing into Ayrshire, was soon enabled to show according to his love of liberty. This man put himself at the a front. Sir James Douglas joined him, and his success became head of the malcontents, and issuing from his cover, raised the so marked and signal, that Edward found himself under the standard of revolt against the foreign king. Hundreds and necessity of marching in person against him. thousands flocked to the rallying post, and in a few days after How Edward did march, and how he died on his way in sight he had declared himself Wallace was at the head of an army of the Scottish border, and how before he died he made his son respectable for its numbers, and for the thoroughly good stuff promise to carry his unburied corpse with the army till Scotof which it was composed. Availing himself of his intimate land should have been subdued, are matters of history. So is knowledge of the country, Wallace effected a series of surprises it matter of history how, six years afterwards, in 1313-14, that on the English garrisons, which fell before him like huts before son marched with an enormous army, and how at Bannockburn, an avalanche. Ormesby, Earl Warenne's deputy, fled from Scone on the 25th of June, 1314, Bruce overthrew him, and routed on hearing that an attempt would be made to take him there, and with irretrievable loss, both of men and prestige, the whole he carried to his chief the news of the rising of the Scots. English army, inflicting a greater blow than the English arms
With 40,000 men Earl Warenne marched northwards, and had suffered since the conquest, and establishing once and for meeting Wallace at Cambuskenneth, near to Stirling, thought ever the independence of the kingdom of Scotland. to crush him by sheer weight; but the Scotch captain, who Several futile attempts were subsequently made, as on the had meantime been joined by Sir William Douglas and many occasion referred to at the beginning of this article, to assert other noblemen, so skilfully conducted himself that he was the English supremacy over Scotland, and the English kings able to fall on the English piecemeal, and utterly to defeat for some time consoled themselves with the barren comfort of them ere their whole strength could be displayed. The hated refusing to recognise the kings of Scotland as independent; but Cressingham was among the slain, and report has it that his since the well-won battle of Bannockburn was fought, the ques. body was flayed, and that the Scots made saddle-girths of his tion was never put practically to Scotland, as it had been skin. Earl Warenne retreated across the border, and Wallace, done before, which of the realms should be the greater. The finshed with victory, carried the war into England, and ravaged same inconveniences which the policy of Edward I. sought to and plundered the whole bishoprio of Durham.
remove continued to present themselves; Scotland remained a Edward, on receiving this news, came over from Flanders, source of danger, a thorn in the side, to England; national antiand hastily marched to the north with an army computed at pathies, aggravated by constant provocations, and finding vent 100,000 men. At Falkirk, on the 22nd of July, 1298, he en perennially in border warfare, were fostered between the two countered the Scots' army under Wallace, and entirely routed countries, till the death of Queen Elizabeth opened the way to a it, with an enormous loss in killed and wounded. So exhausting, community of interest, and a unity of state policy. Whenever, however, was the effort, that Edward retreated instead of after Bannockburn, there was fighting between England and following up his success, and the Scots employed the interval Scotland, it was always conducted on the principle of equality in trying to get help both from the French king and the pope. in status in the belligerents; the words “lord paramount” and The former refused the slightest assistance, but the pope," vassal” were no longer heard ; and the Scots, jealous of any, Boniface VIII., took up the matter by.ordering Edward to refer the slightest dictation, whether from Southron or any other, were his claims to the papal arbitration, seeing that the pope was always ready to "fight for the liberty which was dearer to them lord paramount of all the kingdoms in the world. The English than life." king, however, quickly disposed of this claim by informing the It is a common error to suppose that when James VI. of pope that “neither for Zion nor Jerusalem would he depart Scotland and I. of England ascended the English throne, the from his just rights while there was breath in his nostrils ;” and crowns of the two countries resting upon one head, united the the English Parliament, before whom the pope's bull was laid, two kingdoms. England and Scotland remained separate and resolved with one voice, “ that in temporal matters the King of distinct in every respect, save as to their king ; they had sepaEngland was independent of Rome, and that they would not rate parliaments, separate laws, a distinct religion, different permit his sovereignty to be questioned.”
social customs. There was not, of course, the same danger to The war with Scotland went on for two years with changeable either country as there had been before the power of peace or fortane, the Scots on the whole getting the beet of it, when in war centred in one man; but the national antipathies and preju1302-1303, Edward took the matter in hand himself, and entering dices became probably stronger for being brought more closely Scotland with a powerful army, applied himself vigorously to into contact. All through the English civil war the Scots acted the campaign. Town after town succumbed to him, the magic as an independent people, and refused to meet the English in a of his skill made the strong places yield, and the heart of Scot-common council, though they were engaged in a common cause. land became chilled, as stroke after stroke of his heavy sword It was not till 1707, when Queen Anne was on the throne, that fell upon her devoted children. The English dominion was the union of England and Scotland into one kingdom under the re-asserted in almost every part, and when in 1304 William name of Great Britain, was accomplished. Not without much Wallace was betrayed by Sir John Monteith, and subsequently difficulty, much delicate negotiation, much giving and taking, beheaded in London as a traitor, hope itself seemed to be dead was the union effected; the Scots were jealous of the people within the Scottish breast.
| who proposed to absorb them; the English were impatient and huffy at the touchiness and susceptibility of the Scots. But the creased so that falls; the weight, w, will then be raised; and let conditions, contained in twenty-five articles, having been agreed this continue till it has been raised through a space of, say, two to, the two realms were so inseparably united that nothing short inches. Now, since it is supported by the cords, or rather the of successful revolution could ever sunder them again. The two parts A B, A C of the same cord, it is plain that each must principal conditions of the union are appended, not only in jus. be shortened by the same quantity-namely, two inches—and to tification of this assertion, but because they are not themselves effect this, P must move through four inches, or double the space generally known.
passed over by w. Thus while, on the one hand, a power of The Parliaments of the two countries agreed that
one pound will balance a weight of two, the power must, on the 1. On the 1st of May, 1707, and for ever after, the kingdoms other hand, be moved through four inches in order to move the of England and Scotland shall be united into one kingdom, weight through two, or, in other words, the power is only one-half under the name of Great Britain.
the weight; but in order to raise the weight any given distance, 2. The succession to the monarchy of Great Britain shall be it must move over twice that distance. This rule is frequently the same as was before settled with regard to that of England. expressed as follows:
3. The united kingdom shall be represented by one Parlia Whatever is gained in power is lost in time; that is, if by any ment.
of the mechanical powers we are enabled to overcome a larger 4. There shall be a communication of all rights and privileges resistance than the power could if directly applied, in just that between the subjects of both kingdoms, except where it is other proportion will the space through which the power moves be wise agreed.
larger than that through which the weight moves, and therefore 5. When England raises £2,000,000 by a land-tax, Scotland the time occupied will be proportionally longer. shall raise £48,000.
This simple principle applies to all the mechanical powers, and, 16, 17. The standards of the coin, of weights, and of mea- when fully understood, clears up many difficulties, and removes sures, shall be reduced to those of England throughout the apparent paradoxes. It is, therefore, important for us to be united kingdoms.
clear about it. A machine cannot create force; it merely 18. The laws relating to trade, customs, and the excise, shall modifies the force or motion of the power, so as to cause it best be the same in Scotland as in England. But all the other laws to produce the resistance or motion required. The power must of Scotland shall remain in force, although alterable by the Par- be supplied by some "prime mover," as it is called, such as liament of Great Britain.
the force of the wind or the tide, the strength of men or 22. Sixteen peers are to be chosen to represent the peerage of animals, or the force of heat, which converts water into steam. Scotland in Parliament, and forty-five members to sit in the But when we have the force we can store it up, as is the case House of Commons. (The Reform Act of 1832 added eight in a clock or watch, where the real driving power, which is the members, and Mr. Disraeli's Bill of 1868 proposed to add seven force of the hand exerted in winding it up, is laid up in the more.]
spring and used gradually; the spring not being, as it is 23. The sixteen representative peers of Scotland shall have commonly called, the moving power, but merely a kind of all privileges of Parliament; and all peers of Scotland shall be reservoir in which it is stored up for future use. Or we can peers of Great Britain, and rank next after those of the same modify and change the mode of action of our force, as in a degree at the time of the union, and shall have all privileges of water-mill, where the onward force of the stream is changed peers, except sitting in the House of Lords, and voting on the into the circular motion of the millstone, or applied in any other trial of a poer.
way that may be desired.
If by the movable pulley a man can lift a weight of two MECHANICS.—XI.
hundred-weight to any given height-say, for instance, four feet
—when without it he can only lift one hundred-weight, it will take PRINCIPLE OF VIRTUAL VELOCITIES—THE THREE SYSTEMS
him twice as long to do it, and the practical result will be the OF PULLEYS.
same as if he divided the weight into two of one hundred-weight In our last lesson we noticed the two kinds of single pulleys, each, and lifted each separately; the only difference being one the fixed and the movable. In the fixed pulley there is no gain of convenience, for by it he can lift a weight which otherwise at all in power, a force of 1 pound will only support a weight of would be too heavy for him to move. the same amount. What, then, is the advantage of it? Simply If we for a moment retrace our steps, and see the application this, that it enables us to change the direction in which any of this principle to the mechanical powers we have already force acts; this is, however, very often as great an advantage considered, we shall perceive more distinctly its full meaning as an increase of power would be.
and importance. Suppose, for instance, a man wants to raise a heavy bale to Let us take again the case of a lever of the first kind. the top of a warehouse. He might go to the upper story, and
Suppose the power to act lift it by pulling in a rope tied round it; but this would be a
at a distance from the fal. very bad way of applying his force, and would soon tire him,
crum, F, five times as great and, at the same time, there would be a great danger of his
as the weight does; let PF overbalancing himself and falling. Instead of this, the rope is
be, for instance, 10 feet, passed over a pulley fixed to an arm which projects from the
and Fw 2 feet. Then a warehouse, and he stands within, or
power of 3 pounds will on the ground, and by pulling down.
balance a weight of 15 wards raises the bale.
pounds. If p be now In the single movable pulley there slightly increased, w will be raised that is, a weight of 18 is, as we saw, an actual gain, a power pounds will be lifted by a force only slightly greater than of one pound balancing a weight of pounds. This at first sight seems very strange, and a contra two pounds. The single fixed pulley, diction of our principle that a machine cannot create force. or runner, is often used with this, not But let us suppose that p has moved to P', so that the lever la that it increases the advantage gained, now in the position of the dotted line p'w', w having likewise but merely to change the direction, it moved to w'; P will have passed over the arc PP', and w over being usually more convenient for the | ww: and since F pis five times as creat as FW, PP is also, by power to act downwards than upwards. the laws of geometry, five times as great as ww. You can
Now, if we turn our attention to the easily satisfy yourself of this by actual measurement. And so,
figure, we shall learn from it a new though the power has lifted & weight five times as great as Fig. 70. and very important principle, which, itself, in order to do so, it has had to pass over & space five
though it strictly belongs to dynamics, times as large as that passed over by the weight. time being taken into account, we had better inquire into now, | We thus get another way of expressing our principle, which as it will help us more clearly to understand our subject. I should be carefully remembered :
We have supposed that there is equilibrium in the system, The power multiplied by the space through which it moves that is, that the power exactly balances the weight, being, in this equal to the weight multiplied by the space through wbica case just one-half of it. Now, let the power be slightly in. mores.