Part 10

The conversion into solid land of the Lake of Beemster, in North Holland, is, after the Haarlemmermeer Polder (which is twice and a half its size), the largest specimen in the Netherlands of what the Dutch term "dry-makings." The scheme was first broached in 1570. In 1592 funds were applied for, which were not, however, promised by the States of Holland and West Friesland until 1597. In 1607, a company was formed at the Hague, by Dirck van Oss and others, to pump out the Beemster in whole or in part; and on their security the States lent the necessary capital. At the commencement, it was thought that sixteen windmills would suffice for the undertaking; but this number was shortly increased by ten, and the twenty-six mills were then divided into thirteen gangs. By the end of 1608, several of the mills began to pump, and early in 1609, they were all ready. Towards the end of this year, the bottom of the lake became visible in some places: but during a storm on the 23d of January 1610, the great waterland sea dyke gave way, and the pressure on the ring dyke that had been constructed round the Beemster proved greater than it was capable of resisting. It gave way in turn in two places, and the lake was again filled. On the 5th February 1610, further and ample funds were advanced by the States; in 1611, more mills were put on to the work; on the 19th of May 1612, the dry-making was at last completed; and on the 30th July of that year, the distribution of the lots of land redeemed took place. The ring dyke is over 37,000 yards long, and has an average height of × 1·50 Z. P. (a metre and a half above the mean level of the sea). Thus was the Beemster pumped out; and from that day to the present, the name of Dirck van Oss has been held in deep respect in Holland, as the name of the first Dutchman who conquered the waters on anything like a large scale. The system he employed has been closely followed in all successive undertakings of this kind; and, with the exception of the application of steam, and certain improvements in machinery, the plans of Dirck van Oss for draining the Beemster were adapted with a like success to the Lake of Haarlem, by M. Gevers d'Endegeest, the hero of this last conquest, and the sanguine prophet (1867) of the ultimate reclamation of the Zuyder Zee. The drainage of the Lake of Haarlem, it may be mentioned, was accomplished in 1852, after thirteen years of toil and anxiety, at a cost of 11,000,000 florins (£916,666); a sum which, large as it is, has nevertheless been completely recovered, both in capital and interest, by the sale of 42,481 acres of arable land.--_Report to Foreign Office._

A SCIENTIFIC PILGRIM.

When Lord Napier (of Merchiston) first published his _Logarithms_, Mr. Briggs, Professor of Mathematics at Gresham College, London, was so surprised with admiration, that he could not rest till he had seen the noble inventor, and actually went to Scotland for that purpose in 1615. Lilly, the astrologer, thus describes the interview:--"Mr. Briggs appointed a certain day when to meet at Edinburgh; but, failing thereof, Merchiston was afraid he would not come. It happened one day, as John Marr and the Lord Napier were speaking of Mr. Briggs: 'Ah! John,' said Merchiston, 'Mr. Briggs will not come.' At the very instant, one knocks at the gate; John Marr hastens down, and it proved to be Mr. Briggs, to his great contentment; he brings Mr. Briggs up into my Lord's chamber, where almost one quarter of an hour was spent, each beholding the other with admiration before one word was spoken. At last, Mr. Briggs began, 'My Lord, I have undertaken this long journey purposely to see your person, and to know by what engine of wit or ingenuity you came first to think of this most excellent help unto astronomy, viz. the logarithms; but, my Lord, being by you found out, I wonder nobody else found it out before, when now, being known, it appears so easy.'" Briggs was nobly entertained by Lord Napier; and every summer after, during his lordship's life, this venerable man went to Scotland purposely to see him.

THE BURNING MIRRORS OF ARCHIMEDES.

Many have questioned the facts recorded by several historians, concerning the surprising effects of the burning mirrors of Archimedes, by means of which the Roman galleys besieging Syracuse were consumed to ashes. Descartes, in particular, discredited the story as fabulous; but Kircher made many experiments with a view of testing its credibility. He tried the effect of a number of plane mirrors; and, with five mirrors of the same size, placed in a frame, he contrived to throw the rays reflected from them to the same spot, at the distance of more than 100 feet; and by this means he produced such a degree of heat, as led him to conclude that, by increasing their number, he could have set fire to inflammable substances at a greater distance. He likewise made a voyage to Syracuse, in company with his pupil Schottius, in order to examine the place of the alleged transaction; and they were both of opinion, that the galleys of Marcellus could not have been more than thirty paces from Archimedes' mirrors.

M. Buffon also constructed a machine, consisting of a number of mirrors, by which he seems to have revived the secret of Archimedes, and to have vindicated the credit of history in this respect. His experiment was first made with twenty-four mirrors, which readily set fire to combustible matter composed of pitch and tow, and laid on a deal board at the distance of seventy-two feet. He further pursued the attempt by framing a kind of polyhedron, consisting of 168 pieces of plane looking-glass, each six inches square; and by means of this machine, some boards of beech-wood were set on fire at the distance of 150 feet, and a silver plate was melted at the distance of 60 feet. This machine, in the next stage of its improvement, contained 360 plane mirrors, each eight inches long and six broad, mounted on a frame eight feet high and seven broad. With twelve of these mirrors, light combustible matter was kindled at the distance of twenty feet; with forty-five of them, at the same distance, a large tin vessel was melted, and with 117, a thin piece of silver. When the whole machine was employed, all the metals and metallic minerals were melted at the distance of twenty-five and even of forty feet. Wood was kindled in a clear sky at the distance of 210 feet. M. Buffon afterwards constructed a machine which contained 400 mirrors, each six inches square, with which he could melt lead and tin at the distance of 140 feet.

But perhaps the most powerful burning mirror ever constructed, was that of Mr. Parker, an eminent glass manufacturer of London; it was made in the begining of this century by one Penn, an ingenious artisan of Islington. He erected an outhouse at the bottom of his garden, for the purpose of carrying on his operations, and at length succeeded in producing, at a cost of £700, a burning lens of a diameter of three feet, whose powers were astonishing. The most hard and solid substances of the mineral world, such as platina, iron, steel, flint, &c., were melted in a few seconds, on being exposed to its immense focus. A diamond weighing ten grains, exposed to this lens for thirty minutes, was reduced to six grains, during which operation it opened and foliated like the leaves of a flower, and emitted whitish fumes; when closed again, it bore a polish, and retained its form. Ten cut garnets, taken from a bracelet, began to run into each other in a few seconds, and at last formed one globular garnet. The clay used by Wedgewood to make his pyrometric test ran in a few seconds into a white enamel; and several specimens of lavas, and other volcanic productions, on being exposed to the focus of the lens, yielded to its power.

A subscription was proposed in London to raise the sum of 700 guineas, in order to indemnify the inventor for the expense he had incurred in its construction, and retain it in England; but, through the failure of the subscription, and other concurring circumstances, Mr. Parker was induced to dispose of it to Captain Mackintosh, who accompanied Lord Macartney in his celebrated embassy to China; and the mirror, much to the loss and regret of European science, was left at Pekin.

MAGNETIC CORRESPONDENCE IN THE SEVENTEENTH CENTURY.

In one of Addison's contributions to the _Spectator_ (No. 241), we find the following curious instance of what may almost be considered as the foreshadowing of the electric telegraph. It is quoted from the writings of Strada, the celebrated Roman Jesuit, who died in 1649. In his "Prolusiones," a series of polished Latin essays upon rhetoric and literature, he gives an account of a chimerical correspondence between two friends, by the help of a certain loadstone, which had such virtue in it, that if touched by two several needles, when one of the needles so touched began to move, the other, though at ever so great a distance, moved at the same time and in the same manner. He tells us that two friends, being each of them possessed of these needles, made a kind of dial-plate, inscribing it with twenty-four letters--in the same manner as the hours of the day are marked upon the ordinary dial-plate. They then fixed one of the needles on each of these plates, in such a manner that it could move round without impediment so as to touch any of the twenty-four letters. Upon their separating from one another into distant countries, they agreed to withdraw themselves punctually into their closets at a certain hour of the day, and to converse with one another by means of this their invention. Accordingly, when they were some hundred miles asunder, each of them shut himself up in his closet at the time appointed, and immediately cast his eye upon his dial-plate. If he had a mind to write anything to his friend, he directed his needle to every letter that formed the words that he had occasion for--making a little pause at the end of every word or sentence, to avoid confusion. The friend, in the meanwhile, saw his own sympathetic needle moving of itself to every letter which that of his correspondent pointed at. By this means, they talked together across a whole continent, and conveyed their thoughts to one another, in an instant, over cities or mountains, seas or deserts.... In the meanwhile (adds the Essayist, playfully), if ever this invention should be revived, or put in practice, I would propose that upon the lovers' dial-plate there should be written, not only the twenty-four letters, but several entire words which have always a place in passionate epistles; as flames, darts, die, languish, absence, Cupid, heart, eyes, hang, drown--and the like. This would very much abridge the lover's pains in this way of writing a letter--as it would enable him to express the most useful and significant words with a single turn of the needle.

NAVIGATION BEFORE THE COMPASS.

Before the invention of the mariner's compass, the Phoenician, the Greek, and the early Italian navigators were compelled to creep from headland to headland, without venturing to quit the shore--except when an island, so near as to be distinctly seen from the continent, offered them an equally secure retreat from the violence of an accidental tempest. Yet, the bolder Norwegians, though exposed to far greater perils, from the habitual inclemency of a high northern latitude, and from the frequent cloudiness of their atmosphere, were in the habit of attempting, and often with success, a voyage of some length upon the ocean. It may be supposed that a patient observation of natural phenomena, attention to the flight of migratory birds and to the direction of currents, and some few simple devices which, being no longer necessary, are now forgotten, served as substitutes for the more valuable guides of modern navigation. Of one of the devices here enumerated, it is related that when Flok, a famous Norwegian navigator, was about to set out from Shetland for Iceland, then called Gardarsholm, he took on board some crows, "because the mariner's compass was not yet in use." When he thought he had made a considerable part of his way, he threw up one of his crows, which, seeing land astern, flew to it; whence Flok, concluding that he was nearer to Shetland (or perhaps Faroë) than any other land, kept on his course for some time, and then sent out another crow, which, seeing no land at all, returned to the vessel. At last, having run the greater part of his way, another crow was sent out by him, which, seeing land ahead, immediately flew for it; and Flok, following his guide, fell in with the east end of the island. Such was the simple mode of steering their course, practised by those bold navigators of the stormy northern ocean. This story at once and strikingly recalls the use made of birds by the first sea captain of whom we read--Noah; but such expedients evidently could not be supposed to have inspired the old northern navigators with the courage and confidence that enabled them, as there is reason to believe, to discover America before Columbus.

SEMAPHORE _v._ ELECTRIC TELEGRAPH.

An anecdote will suffice to illustrate the advantages of the electric over the visual variety of telegraph--the one being only workable in certain states of the weather; the other available in all states. Upon one occasion, when the British army were fighting in Spain, intelligence was every day feverishly expected from Wellington through the medium of the semaphore at the Admiralty. Long delayed, it came at last, and was apparently of a fearful character. It ran thus: "Wellington defeated." Parliament and the people were stunned for a time, and rumours flew about like wildfire to this effect. It turned out, however, that just as the word "defeated" was deciphered, a fog intervened, and cut off the rest of the communication. When the dark pall disappeared, the bright sky disclosed to a jubilant people, not "Wellington defeated," but "Wellington defeated--the French!"

A WRENCH TO OLD ST. PAUL'S.

When, after much mean and yet costly endeavour to patch up the cathedral of St. Paul's, after the great fire, Sir Christopher Wren at last had his advice accepted, to rebuild the whole structure, the demolition of the old fabric gave ample play to his scientific knowledge and engineering skill. One of his exploits, perhaps now more remarkable because at the time it was at once rare and bold, has thus been described:--"In order that the rubbish and old materials might not hinder the setting out of the foundations, for the purpose of proceeding with the works, Sir Christopher constructed scaffolds high enough to extend his lines over the heaps that were in the way; and thereby caused perpendiculars to be fixed upon the points below for his various walls and piers, from lines drawn carefully upon the level plan of the scaffold. Thus he proceeded, gaining every day more and more room, till he came to the middle tower that formerly carried the lofty spire. The ruins of this tower being nearly two hundred feet high, the labourers were afraid to work above, which induced him to facilitate the labour by the use of gunpowder. To perform this work, he caused a hole to be dug, of about four feet wide, by the side of the north-west pier of the tower, in which was perforated a hole two feet square, reaching to the centre of the pier. In this he placed a small deal box containing eighteen pounds of gunpowder. To this box he affixed a hollow cane, which contained a quick match, reaching to the surface of the ground above; and along the ground a train of powder was laid, with a match. The mine was then closed up, and exploded, while the philosophical architect waited with confidence the result of his experiment. This small quantity of powder not only lifted up the whole angle of the tower, with two great arches that rested upon it, but also two adjoining arches of the aisle, and the masonry above them. This it appeared to do in a slow but efficient manner, cracking the walls to the top, lifting visibly the whole weight about nine inches, which suddenly dropping, made a great heap of ruins in the place, without scattering or accident. It was half a minute before the heap already fallen opened in two or three places, and emitted smoke. By this successful experiment, the force of gunpowder may be ascertained; eighteen pounds only of which lifted up a weight of more than three thousand tons, and saved the work of a thousand labourers. The fall of so great a weight from a height of two hundred feet gave such a concussion to the ground, that the inhabitants round about took it for the shock of an earthquake."

SNOW SPECTACLES.

Ellis, in his _Voyage to Hudson's Bay_, written in the middle of last century, says of the Esquimaux:--"Their snow eyes, as they very properly call them, are a proof of their sagacity. They are little pieces of wood or ivory, properly formed to cover the organs of vision, and tied on behind the head. They have two slits, of the exact length of the eyes, but very narrow; and they see through them very distinctly, and without the least inconvenience. This invention preserves them from snow-blindness, a very dangerous and powerful malady, caused by the action of the light strongly reflected from the snow, especially in the spring, when the sun is considerably elevated above the horizon. The use of these eyes considerably strengthens the sight, and the Esquimaux are so accustomed to them, that when they have a mind to view distant objects, they commonly use them instead of spy-glasses."

A SELF-TAUGHT MECHANIST.

The following description is given of an ingenious and singular piece of mechanism--constructed by a boy of the name of John Young, who in 1819 resided at Newton-on-Ayr--which attracted much notice among the scientific of the day:--"A box, about three feet long by two broad, and six or eight inches deep, had a frame and paper covering erected on it, in the form of a house. On the upper part of the box are a number of wooden figures, about two or three inches high, representing people employed in those trades and sciences with which the boy is familiar. The whole are put in motion at the same time by machinery within the box, acted upon by a handle like that of a hand-organ. A weaver upon his loom, with a fly-shuttle, uses his hands and feet, and keeps his eye upon the shuttle, as it passes across the web. A soldier, sitting with a sailor at a public-house table, fills a glass, drinks it off, then knocks upon the table, upon which an old woman opens a door, makes her appearance, and they retire. Two shoemakers upon their stools are seen, the one beating leather, and the other stitching a shoe. A cloth-dresser, a stone-cutter, a cooper, a tailor, a woman churning, and one teasing wool, are all at work. There is also a carpenter sawing a piece of wood, and two blacksmiths beating a piece of iron, the one using a sledge, and the other a small hammer; a boy turning a grindstone, while a man grinds an instrument upon it; and a barber shaving a man, whom he holds fast by the nose with one hand. The boy was only about seventeen years of age when he completed this curious work, and since the bent of his mind could be first marked, his only amusement was that of working with a knife, and making little mechanical figures. This is the more extraordinary, as he had no opportunity whatever of seeing any person employed in a similar way. He was bred a weaver with his father, and since he could be employed at the trade, has had no time for his favourite study, except after the work ceased, or during the intervals; and the only tool he ever had to assist him was a pocket-knife. In his earlier years he produced several curiosities on a smaller scale; but the one now described is his greatest work, to which he devoted all his spare time during two years."

THE AMSTERDAM PILE.

In an interesting report on the "Waterstaat" of the Netherlands, presented to the British Government, we read: "To appreciate the beauty of the Dutch science of hydrodynamics, it is necessary to understand that, from first to last, it is a question of comparative levels. The error of a centimètre in level might drown a province, or frustrate the purpose for which some canal had been designed. Thus it may be said, without exaggeration, that the most important institution in the kingdom of the Netherlands is a certain antiquated pile at Amsterdam--but one of many million pine-trees brought from Norway, on which the city is perched,--which indicates the rise and fall of the outer waters of the Zuyder Zee and German Ocean. For 200 years this pile has been watched with anxiety by the burghers of the Netherlands, and a graduated scale has been marked upon it, in which the mean water level is represented by zero. It is known as the 'Amsterdamsche Peil,' and every hydraulic undertaking in the country is measured by its standard, as having a level of so many mètres or centimètres above or below the usual level of the sea. The initials A. P. (Amsterdamsche Peil), O. A. (Zero of Amsterdam), or Z. P. (Zero of Pile), are the forms of abbreviation most generally used to represent the starting-point in all hydraulic calculations; and one of these, with the signs + and -, must therefore necessarily occur in every intelligible description of Dutch public works."

THE PERILS OF EXPERIMENT.

M. Rouelle, an eminent French chemist, was not the most cautious of operators. One day, while performing some experiments, he said to his auditors: "Gentlemen, you see this cauldron upon the brazier; well, if I were to cease stirring for one moment, an explosion would ensue, that would blow us all into the air." The audience had scarce had time to reflect on this comfortable piece of information, when the operator actually did forget to stir, and his prediction was amply verified. The explosion took place with a terrible crash; all the windows of the laboratory were smashed to pieces, and two hundred auditors were whirled away into the garden. Fortunately, no one received any serious injury, the chief violence of the explosion having been in the direction of the chimney. The demonstrator himself marvellously escaped without further harm than the loss of his wig.--A certain Scotch Professor--not of the present generation--as remarkable for the felicity of his experimentation as Rouelle could be for his failures, was once performing an experiment with some combustible materials, when the mixture exploded, and the phial which he held in his hand flew into a thousand pieces. "Gentlemen," said the Doctor to his students, with the most unaffected gravity, "I can assure you that I have performed this experiment often with the same phial, and never knew it break in my hands before." The simplicity of this somewhat superfluous assurance gave rise to a general laugh, in which the Professor, instantly discerning the cause of it in his own excellent Irishism, most heartily joined.

THE SIBERIAN MAMMOTH REMAINS.