RECREATIVE NATURAL HISTORY.

BRITISH PEARLS AND PEARLY SHELLS.

It would be difficult to find, among the multitudes of strangelyformed and deeply-interesting inhabitants of our lakes, rivers, and the sea which girds our coasts, a wider field for study and research than is presented by an examination of the habits and peculiarities of the shell-bearing Mollusca. Whether we select for investigation the tiny creature in his glass-like dwelling among the green water-weeds freshly culled from the clear brook (a familiar type of which is to be found in the Lymnea stagnalis, the subject of the annexed illustration, Fig. 1); or dredge up from the rock-fastnesses at the sea's bottom some stout and strong sea-castle, like that inhabited by the Triton, figured in the annexed engraving (Fig. 2); or search the grass and herbs growing in some sheltered hedge-row, where the snails and other land-shells love to dwell, we find the same admirable fitness and marvellous adaptation to the position and conditions under which each had existed: and notwithstanding that the one possesses the power of supporting and carrying out the various functions of existence in water far removed from the sea, the other beneath the salt waves of the ocean, and the third in situations far removed from water either fresh or salt, a perfect shell, exquisite in form, admirable in design, and very nearly of identical composition, is secreted in each instance. Many of these terrestrial shells are, notwithstanding the position assigned them by nature, capable of assimilating elements productive of rich, admirable, and varied colouring. The annexed sketch of Helix hemastoma (Fig. 3) will serve to show this. Few of our readers will have failed to observe the beauty of tint and variety of shading to be found on the shells of the common banded and golden-yellow snails of our hedges, lanes, and thickets.

Few natural processes are more extraordinary and mysterious than that by which colour and quality of product are produced by living creatures, and even the lowest orders of plants. We take a grain of wheat, the seed of the poppy, the nur vomica, and the deadly nightshade; we prepare a suitable tub or other vessel for them to grow in; we furnish soil, water, heat, and shelter; and in due time, when the plants from each of these seeds have arrived at maturity, we shall find that no two will be alike either in colour of blossom, form of foliage, or shape of plant. We go a step farther, and subject them and their products to chemical analysis, and we find food suitable for man associated with a plant-stalk covered with a sheath of pure flint in the wheat; whilst the poppy, with its rich scarlet tints and soft stem, yields the useful alkaloid morphia; and the nur vomica furnishes to us the deadly poison, strychnia-all these wondrous elements and compounds being drawn from the one simple tub of earth, and the water with which it was supplied. So it is with the shells of the earth, the river, and the sea: by processes the nature of which we know nothing, results of the most extraordinary nature and magnitude are brought about. Not only the spined and gaily-painted shell of the coral reef, but the very reef itself, destined at some time to form a home for man, is slowly but surely being built up and massed together by the living labourer, who works by laws far beyond our ken. The eggs of birds, too, are marvellous in their form and colouring, and possess a crust or shell closely resembling that of the shells we have been describing, both in texture and component parts. Dealing with shells and structures allied to them, we can easily pile such beautiful works of an all-wise Creator together, apply fire and reduce them to lime; but with all our boasted skill in science and art, no human power or ingenuity could, from the materials thus formed, cause the building up of that which has been so readily torn down. Pearls, after all, are merely lime which has passed through the laboratory of that most wonderful of chemists, the shell-bearing mollusk. For the early history of English pearls, and the shells which yield them, we must go back to a period when Britain was known to other nations as a mere group of islands vaguely known as the Cassiterides. This supposed group was, no doubt, formed by the Scilly Islands and the projecting land of the coast of Cornwall. This region was probably first discovered by a band of Phoenician voyagers who were dispatched about 600 B.C., by Pharaoh-Necho, king of Egypt (the same who slew Josiah, king of Judah). These bold adventurers were directed to set sail from the Red Sea, to voyage round Africa, and enter the northern seas by the Straits of Hercules, when they were to

explore and investigate such countries as they might find, and take note of all valuable productions. On the discovery of the Cassiterides by the Phoenicians, tin and probably pearls formed important objects for commercial enterprises; but the situation of the new treasure-lands was for a long time successfully concealed by the fortunate discoverers. The Romans, however, at length discovered the secret, and there appears little doubt that the glowing accounts given of the fabulous quanti ties of pearls possessed by the inhabitants of "Baratanac,” or Britain, first led Julius Cæsar to plan his second invasion, and decide on its capture and subjugation. That pearls were the great and main attraction is proved by the fact of one of his first offerings to the shrine of Venus Genitrix as a successful conqueror being a shield or buckler covered with pearls from his new possession. Pliny, in writing of this offering, says that the pearls from Britain were of small size, devoid of lustre, and very inferior to those of Eastern origin; Tacitus also speaks of them in much the same terms. It is fair, therefore, to infer that the description of pearl known in those early days was obtained from the common edible mussel (Mytilus edulis, the subject of the accompanying illustration, Fig. 4), which is only met with at the mouths of tidal rivers where the water is strongly impregnated with salt, or in the sea itself. An investigation of the contents of these palatable bivalves will often lead to the discovery of small pearls of little or no commercial value. Some years since, when pearls formed an important element in the prescriptions of medical men, they were far more eagerly sought after than now. The common oyster of our coasts is also occasionally found to yield small or seed pearls, which are of value only to the curious. The great silk mussel (Pinna nobilis, a representation of which is shown at Fig. 5, on a reduced scale) is the largest bivalve shell found in our seas. It not only produces a tuft or tassel of silk-like material, known as the "byssus," which is at times spun into gloves and stockings, but is often found to contain coloured pearls of considerable value. Some of these are of a steel-grey tint, others are lead-coloured, reddish, and occasionally even black. It is not to this shell, however, that we have to look for the true precious pearl of Britain: that is produced by a shell much larger than the edible mussel, bearing no silk, and dwelling exclusively in running streams of fresh water. The rivers of Wales, Ireland, Germany, and Switzerland have been long celebrated for their pearl mussels. The Unio margaritiferus, as it is called by naturalists, represented at Fig. 6 in the accompanying illus tration, is the true fresh-water pearl-shell. It has been found measuring five inches and a half in length, and two inches and a half in breadth across the valves; but it is very rarely so large, the great majority of specimens but little exceeding five inches long by about two inches broad. Some curious information relating to Irish pearls was communicated by Sir Robert Redding, through a Dr. Martin Lister, to the Philosophical Transactions of 1673. He states that the rivers of Derry, Donegal, Tyrone, Wexford, and Kerry contained the pearl mussels, and that the poor people in the neighbourhood of the streams fished for them during the warm weather preceding harvest, when there was little water flowing, and that they made use of either their toes, wooden tongs, or sharp-pointed sticks for dislodging them from their retreats on the bottom or among the stones. The sharp sticks were, he says, thrust between the open valves of the shells "as they lay in part opened, with the white foot protruded like a tongue out of the mouth." He then states as follows:-"Some gentlemen of the country made great advantage thereof; and I myself, whilst there, saw one pear! bought for fifty shillings that weighed thirty-six carats, and was valued at forty pounds. Everybody abounds with stories of the good pennyworths of the country, but I will add one more. A miller took ont a pearl, which he sold for four pounds ten shillings to a man, who sold it for ten pounds, who sold it to the late Lady Gleneally for thirty pounds, with whom I saw it in a necklace. She refused eighty pounds from the late Duchess of Ormond for it."

Scotland, too, particularly in past times, had reason to boast of the importance of her river pearls, the Tay, from Perth to Loch Tay, being one of the richest streams. Captain Brown, in recording the particulars of the Scottish pearl-fishing, says, "The pearls sent from Scotland to London from the years 1761 to 1764 were estimated at ten thousand pounds' value." The Isle of Man, too, has had its river harvest, and a peculiar

variety of the unio (U. roissyi) was found to produce a very noteworthy number of pearls. The river flowing near Braddon was that most successfully fished. The river Conway, in North Wales, has for ages been known to be one of the chosen homes of the pearl shell, as both the salt-water mussel at the river's mouth, and the unio high up among the brawling rills which ripple among the hazels and yellow furze blossom, bear with them ever and anon the much-coveted treasure. Bettwsy-Coed has, so tradition says, the honour of being the locality near which the bold and handsome Welsh nobleman, Sir Richard Wynne, obtained the rich and costly pearl which he presented to the queen of Charles II. The term "Cregin diluw" has been by the Welsh given to the Conway shells from an idea, which they appear to have entertained, that they were brought to the river at the time of the deluge. The formation of pearls in the

appears no reason why they should not be found as abundantly as when Sir Robert Redding wrote: speaking of the proportion of prizes to blanks, he says, "Although, by common estimate, not above one shell in a hundred may have a pearl, and of these pearls not above one in a hundred be tolerably clear." Yet a vast number of fair merchantable pearls, and too good for the apothecary, are offered for sale by these people every summer assize."

The streams of Bavaria at the present day produce from time to time pearls well worth obtaining, and about thirty years since a most important find of them was made by mere chance in Norway. An unusually dry summer had caused the waters of the Zeddern Channel to become nearly dry. A peasant who chanced to be wandering about over the shingle and pebbles, seeing a dead and partially dried unio laying in its

1. LYNNEA STAGNALIS.

2. TRITON.

tissues of this or any other mollusk can be only viewed in the light of a diseased or abnormal secretion, caused in the majority of cases by the presence of some foreign and irritating cause. Linnæus discovered by actual experiment that grains of sharp sand introduced between the valves of the shell in such a way that they rested between the body of the animal and the "mother-of-pearl," or shell-lining, caused in a short time the deposition of a coating or crust of pearl on the sand grain, which, acting as a nucleus, gathered the shielding matter around it, and so guarded the delicate tissues of the mollusk from friction and injury. It has also been found that by drilling a small hole through the outer coatings of the shell, and leaving the lining untouched by the boring instrument, that a pearl nodule was in a short time formed, as shown in the annexed illustration (Fig. 7), so as to defend the weak point, just as a skilful armourer would patch a weak place in breast or back plate. It is somewhat remarkable that the search for home pearls should be so rarely followed at the present day, as there

wide-spread shell, stopped, and picked it up, when, much to his wonder and delight, out rolled a pearl worth £50. Specimens of even greater value than this were soon after discovered by the people, who rushed from far and near to the treasure-yielding sands, which were thoroughly searched until the return of the water to its accustomed level put a stop to the search. A shell closely resembling the Unio margaritiferus is to be found in most of the ponds, brooks, and rivers of England; it is known as the "pond mussel," or Adonta. A reference to Fig. 8 will at once show the particulars of external form in which the two shells differ. The Adonta, so far as we have observed, yields no pearls, but produces an incredible number of young adontas, which are carried within the parent shell completely valved and ready to shift for themselves when cast on the world of waters. It is said that an American naturalist has succeeded in computing one Adonta family at 600,000 in number. There are many more shell-dwellers interesting in habits and curious in form, and to these we hope to refer in another paper.

Present,
First Aorist,
Second Aorist,

Λιπεσθαι.

PARTICIPLES.

λυ-ομενος, loosing one's self.

λυ-σ-αμενος, having loosed.

λιπ-ομενος, λαving remained behind,

EXERCISE 76.-GREEK-ENGLISH.

1. Λυοιμην. 2. Λυσοιμην. 3. Λυομαι. 4. Λυωμαι. 5. Ελυόμην. 6. Ελυσαμην. 7. Λυσομαι. 8. Ελιπομην. 9. Λυονται. 10. Ελνοντο. 11. Ελυσαντο. 12. Λυσαισθε. 13. Λιποιμην. 14. 15. Λιπόμενος. 16. Λυσασθαι. 17. Λυεσθαι. 18. Λυόμενος. 19. Λύσασθε. 20. Λιπωμαι. 21. Ελυσω. 22. Λυσηται. 23. Λυεσθων. 24. Λυοισθον. 25. Λυομενου. 26. Ελύεσθε. 27. Λυσαμενοι. 28. Λυοιντο. 29. Λυσαίμεθα.

EXERCISE 77.-ENGLISH-GREEK.

1. I might loose myself. 2. He might loose himself. 3. They might loose themselves. 4. To loose one's self. 5. Loosing one's self. 6. Loose yourselves. 7. He would loose himself. 8. Let him loose himself. 9. We may have loosed ourselves, 10. They will loose themselves. 11. He may loose himself. 12. You two might have loosed yourselves. 13. You may have loosed yourself. 14. They remained behind. remained behind. 16. Do ye remain behind. one's self.

15. He may have 17. To have loosed

Conjugate, according to the active and middle paradigms, these verbs :παιδεύω, I instruct, educate ; βασιλεύω, Ι τείχη. The chief parts are-παιδεύω, παιδεύσω, πεπαιδευκα, πεπαιδευμαι, and βασιλεύω, βασιλεύσω, βεβασιλευκα, βεβασιλευμαι.

THE PASSIVE VOICE OF λυω.

(The Present and Imperfect are the same as in the Middle Voice.)

INDICATIVE MOOD.

First Aorist. Tense-stem ε-λυ-θ

Sing. 1. ε-λυ-θ-ην, I was loosed, etc. 2. ε-λυ-θ-ης.

3. ε-λυ-θ-η.

Dual. 2. ε-λυ-θ-ητον.

3. ε-λυ-θ-ητην.

Plur. 1. ε-λυ-θ-ημεν.

2. ε-λυ-θ-ητε.

3. ε-λυ-θ-ησαν.

First Future.Tense-stem λυ-θη-σ.. Sing. 1. λυ-θη-σ-ομαι, I shall be loosed, etc. (Like the Indicative Present Middle.)

Second Aorist.Tense-stem ε-τριβ. Sing. 1. ε-τριβ-ην, I was rubbed, etc. (Like the Indicative First Aorist Passive.) Second Future.Tense-stem τριβ-η-σ-. Sing. 1. τριβ-η-σ-ομαι, I shall be rubbed. (Like the Indicative First Future Passive.)

Perfect.—Tense-stem λε-λυ-, Sing. 1. λε-λυ-μαι, I have been loosed, etc.

2. λε-λυ-σαι.

3. λε-λυται. Dual. 1. λε-λυ-μεθον.

2. λε-λυ-σθον. * 3. λε-λυ-σθον. *

Plur. 1. λε-λυ-μεθα.

2. λε-λυ-σθε.

3. λε-λυ-νται.

Pluperfect.—Tense-stem ε-λε-λ».

ε-λε-λυ-μην, I had been
loosed, etc.
ε-λε-λυ-σο.

ε-λε-λυτο.

ε-λε-λυ-μεθον.

ε-λε-λυ-σθον.

ε-λε-λυ-σθην.

ε-λε-λυ-μεθα.

ε-λε-λυ-σθε.

ε-λε-λυ-ντο.

Note that when the tense-ending uai of the perfect passive is preceded by a consonant the third person plural is supplied, for euphony's sake, by the perfect participle with e-for TETUTITUI, τετυμμένοι εισι—and in the pluperfect τετυμμενοι ησαν.

λυτος, loosed.

1. Ετριβη.

VERBAL ADJECTIVES.

λυτεος, one who ought to be loosed. EXERCISE 78.-GREEK-ENGLISH.

2. Τριβῃ. 3. Τριβειης. 4. Τριβειη. 5. Λυθειητην. 6. Λυθείεν. 7. Λυθητω. 8. Λυθηναι. 9. Λυθησομενος. 10. Τριβηναι. 11. Τριβησομενος. 12. Ελυθης. 13. Ελυθητε. 14. Λυθησῃ. 15. Λυθωμεν. 16. Λυθείημεν. 17. Λυθωσι. 18. Λυθεις. 19. Λυθησεσθαι. 20. Τρίβεις. 21. Τριφηθήτω. 22. Λελυμαι. 23. Ελελυμην. 24. Λελυσομαι. 25. Λέλυνται. 26. Ελελυντο. 27. Λελυμένος είης.

EXERCISE 79.-ENGLISH-GREEK.

1. He was loosed. 2. He may have been loosed. 3. He might have been loosed. 4. He shall be rubbed. 5. They shall be loosed. 6. He was rubbed. 7. I have been loosed. 8. Thou mayest have been loosed. 9. They shall have been loosed.

Of the participles in the middle and passive voice, those which end in os (μενος) are declined like αγαθος, -η, -ον. Of those which end in eis, take the following as a model :DECLENSION OF λυθεις, λυθεισα, λυθεν, loosed.

λελυμένω, ειητον.

λε-λυ-μενω, ειητην.

Dual.

λελυμένοι, -είημεν.

λελυμένοι, -είητε. λελυμένοι, είησαν.

First Future.Tense-stem λυ-θη-σ-. Sing. 1. λυ-θη-σ-οιμην, I would be loosed. (Like the Optative Imperfect Middle.)

Plur. 1. λυ-θ-ειημεν.

2. λυ-θ-ειητε.

3. λυ-θ-ειεν.

λυθέντοιν, λυθεῖσαιν,

Second Aorist.-Tense-stem τριβ.. Sing. 1. τριβ-ειην, I would be rubbed. (Like the Optative First Aorist Passive.) Second Future.Tense-stem τριβ-η-ς-. Sing. 1. τριβ-η-σ-οιμην, I would be rubbed. (Like the Optative First Future Passive.) Perfect Future, or Third Future.Tense-stem λε-λυσ Sing. 1. λε-λυ-σ-οιμην, I would have been loosed. (Like the Optative Imperfect.)

KEY TO EXERCISES IN LESSONS IN GREEK.-XXVI.
EXERCISE 74.-GREEK-ENGLISH.

1. Loosing. 2. Τo be about to loose. 3. He is loosing. 4. I have loosed. 5. I had loosed. 6. I shall loose. 7. Ye two would loose. 8. Thou wouldest loose. 9. Let him loose. 11. I was 10. Loose ye. loosing. 12. He shall loose. 13. We are loosing. 14. Ye two were loosing. 15. I might loose. 16. I loosed. 17. He has loosed. 18. He loosed. 19. I might have, loosed. 20. Loose thou. 21. Let them two loose (aor.). 22. Having loosed. 23. I may have loosed. 24. Thou hast loosed. 25. They had loosed. 26. They loosed. 27. They have loosed. 28. Ye might have loosed. 29. Thou mayest have loosed. 30. Thou hast appeared. 31. Thou didst leave. 32. Thou mayest have left. 33. Thou mightest have left. 34. Let him leave. 35. Having left. 36. To have appeared. 37. Thou hadst appeared. 38. He might have appeared. 39. He might loose. 40. They might loose.

EXERCISE 75.-ENGLISH-GREEK.

1. Πέφηνα. 2. Ελιπέτην. 3. Λειποι. 4. Λειποιτε. 5. Λυουσι. 6. Λνωσι. 7. Ανοιεν. 8. Λύσαιτε. 9. Λυε. 10. Λυοντων. 11. λελυκα. 12. Λύσετε. 13. Λυσωσι. 14. Λυσεις. 15. Λύειν. 16. Λύσειν. 17. Λύσων. 18. Λύσας. 19. Λυῃ. 20. Ελελυκειτην. 21. Λυοιτην. 22. Λυητον. 23. Πεφηνασι. 24. Πεφηνατον. 25. Πέφηνε.

LESSONS IN ALGEBRA.-XVII.

SOLUTION OF PROBLEMS.

171. For the solution of problems in Simple Equations, we derive from the preceding principles the following general rule:RULE.-1. Translate the statement of the question from the ordinary language into algebraic language, in such a manner as to form an equation; that is, put the question into the form of an equation.

2. Clear the equation of fractions by multiplying every term in both members by all the denominators successively, or by their least common multiple.

3. Transpose all the terms containing the unknown quan

the one side of the equation, and all the known quantities to the other, taking care to change the signs of the terms transposed, and incorporate the terms that are alike.

4. Remove the co-efficient of the unknown quantity, by dividing all the terms in the equation by it; the result will be the solution required.

PROOF.-Substitute the value of the unknown quantity for the letter which stands for it in the equation; and if the number satisfies the conditions of the question, it is the answer sought. PROBLEM 1.—A man being asked how much he gave for his watch, replied: If you multiply the price by 4, to the product add 70, and from this sum subtract 50, the remainder will be equal to 220 pounds.

In order to solve this question, we must first translate the conditions of the problem into such an algebraic expression as will form an equation.

16 2

- 20

=

16 4

J&

3

and re

PROOF. Thus 16+ PROBLEM 3.-A father divides his estate among his three sons in such a manner, that the first has £1,000 less than the whole; the second has £800 less than one-third of the whole; the third has £600 less than one-fourth of the whole. What is the value of the estate? Ans. £4,1143.

PROBLEM 4.-Divide 48 into two such parts, that if the less be divided by 4, and the greater by 6, the sum of the quotients

will be 9.

=

9.

Let be the smaller part; then 48-x is the greater part; and, 48- -x by the conditions of the problem, we have + 6 Whence x = 12; therefore, 12 is the less part, and 36 the greater part. 172. Letters may be employed to express the known quantities in an equation, as well as the unknown. A particular value is assigned to the letters, when they are introduced into the calculation; and at its close, the numbers are restored.

EXAMPLE. If to a certain number 720 be added, and the sum be divided by 125, the quotient will be equal to 7392 divided by 462. What is the number? Let be the number required; and let a = d=7392, and h = 462.

720, b = 125,

bd — ah h

x + a d ს

h

(125 × 7392)-(720×462)

462

Then, by the conditions of the problem, we have and reducing, we have x =

Restoring the numbers, we have x=

EXERCISE 29.-MISCELLANEOUS PROBLEMS IN SIMPLE

EQUATIONS.

2. Divide 39 into four parts, such that if the first be increased by 1, the second diminished by 2, the third multiplied by 3, and the fourth divided by 4, the results may be all equal.

3. If a certain number is divided by 12, the quotient, dividend, and divisor, added together, will amount to 64. What is the number?

4. An estate is divided among four children, in such a manner that the first has £200 more than of the whole, the second has £340 more than of the whole, the third has £300 more than of the whole, the fourth has £400 more than of the whole. What is the value of the estate?

5. What is that number which is as much less than 500, as a fifth part of it is greater than 40 ?

6. There are two numbers whose difference is 40, and which are to each other as 6 to 5. What are the numbers?

7. Suppose two coaches to start at the same hour, one from London for Glasgow, and the other from Glasgow for London, the former travelling 10 and the latter 9 miles per hour. Where will they meet, the distance between the two cities being 400 miles ?

8. Suppose everything to be as in the last question, except that the coach from Glasgow starts two hours earlier than the other. Where will they meet?

9. A dealer purchases 60 yards of cloth for £30; and by selling one part of it at 12s., another, twice as great, at 14s, and the rest at 10s. per yard, he gains £8. How many yards were in the several lots ?

10. Suppose two dealers each annually to double his capital, except an expenditure of £100; and that at the end of three years the capital of one is found to be doubled, while the other has only half what he had at first. How much had each to commence with ?

11. If a person each year double his capital, except an expenditure of £300 the first year, £400 the next year, and £500 the third, and at the end of three years be found to be worth £5,500, what was his original capital ?

12. A father's age is now treble of his son's, while five years ago it was quadruple. What are their present ages?

13. Divide £1,000 between A, B, and C, giving A £100 more, and B £50 less, than C.

14. A spirit merchant finds that if he add 10 gallons to a cask of brandy, the mixture will be worth 21s. per gallon; but that if he had ten gallons more, the value will be reduced to 188 How many gallons were in the cask?

15. Find a number, such that if it be divided successively by 2, 3, 4, 5, 6, 7, 8, 9, and 10, half the sum of the first four quotients increased by 20 shall be equal to the sum of the remaining five.

16. Find two numbers differing by 6, and such that three times the less may exceed twice the greater by 7.

17. Find a number, such that if it be increased successively by 1, 2, and 3, the sum of one-half of the first result and onethird of the second shall exceed one-fourth of the third by 8.

LESSONS IN ITALIAN.-XIV
EXERCISES FOR PRACTICE.

WE resume in this lesson our series of exercises which will
afford the student sufficient practice in translating simple se
tences in Italian into English, and turning English into Italian
The copious vocabularies will afford the learner a useful oppor
tunity of storing his mind and memory with Italian words.
VOCABULARY.
E's-so, m., ès-sa, f.,
he, she, it (of per-
sons and things).
П cap-pel-lo, the hat.
Il ca-vál-lo, the horse.
Il fan-ciál-lo, the child.
Il tem-pe-ri-no, the pen-
knife.

mól-to grán-de. 5. Hô com-prá-to ú-na pén-na; és-sa è mol-t