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in agayne." Ben Jonson, in his Siletit Woman, published in 1607, makes one of the characters say : "A most vile face! and yet she spends me forty pound a year in mercury and hog's bones. All her teeth were made in the Blackfriars/" An almanac for the year 1709 makes mention of one John Watts, who was the maker of artificial teeth in Racket Court, Fleet Street. The Sunda Islanders at the present day are in the habit of employing their old women to dress up the teeth of the youths and maidens at wooing-time; the canine teeth are filed to a fine smooth edge, and the body of the tooth made concave, or they will notch the edge of the teeth like a fine saw, as an additional means of beautifying. An imperial toolh-ache once made the fortune of a poor barber. The present Sultan of Turkey, Abdul Aziz, having a touch of toothache one day, sent for the court physician; he was hunting, and could not be found. The domestics hurried about Constantinople, and at length found a poor ragged barber-surgeon; they took him to the palace, and furbished him up. He drew the offending tooth, and soothed the pain of the Commander of the Faithful. Whereupon a nice house and sixteen hundred piastres a month were awarded to him.

During the days of the resurrectionists or body-snatchers, when grave-yards were subjected to pillage for supplying anatomists with subjects for dissection, the teeth from the dead bodies formed a frequent article of sale to dentists. Sometimes graves were opened for the teeth alone, as being small and easily concealed articles. Mr Cooper, the surgeon, relates an instance of a man feigning to look out a burial-place for his wife, and thus obtaining access to the vault of a meeting-house, the trap-door of which he unbolted; at night he let himself down in the vault, and pocketed the front teeth of the whole of the buried congregation, by which he cleared fifty pounds ! Mention is made of a licensed sutler or cantineer during the Peninsular War, who "drew the teeth of those who had fallen in battle, and plundered their persons. With the produce of these adventures, he built a hotel at Margate. But his previous occupation being discovered, his house was avoided, and disposed of at a heavy loss." He afterwards became a dealer in dead men's teeth.

The making of artificial teeth is a trade

in which a large amount of ingenuity is displayed, both in the adaptation of new substance, and in the modes of shaping and finishing. When artificial teeth began to be made, instead of using the natural teeth of dead persons, they were made of bone, or the more costly kind of ivory, from the tusks of the elephant, rhinoceros, hippopotamus, walrus, or narwhal. If only a single tooth were wanted, it was customary to cut a bit of bone to the proper shape, and tie it to the next tooth by a ligature of wire. It is still found that tusk-bone possesses the best combination of properties. It combines, as a learned authority in the dental world, tells us, "lightness, strength, and solidity, with a natural appearance and a certain congeniality to the mouth, possessed by no other material, which render both partial pieces and entire sets at once the most useful substitutes for the lost natural teeth."

The mechanical dentist must be a genuine workman. When he is about to make bone or ivory teeth, he cuts a tusk into pieces, and shapes each piece by an elaborate series of mechanical processes. Sometimes for a customer who has plenty of guineas to spare, he will make a whole set, upper or lower, as the case may be, out of one piece. He saws his block of ivory roughly to the size; and then, with infinite patience, files and graves it into shape. He has at hand a model of the patient's gum, and works to that model with exactness. The teeth are not separate pieces; they are cut into apparent rather than real separation, like the teeth of a comb. An artistic workman will take care that the teeth shall present some of that irregularity which our natural grinders always exhibit; a learner falls into the mistake of making them too good. Many persons do not like to w-eardead people's teeth; there is something uncomfortable in the idea; there is also frequently a germ of decay in such teeth; and these two reasons led to the custom of making artificial ivory teeth. Ivory, however, with all its excellences, becomes discolored; and hence the chief motive for making teeth of certain mineral or vegetable compositions. There is, in fact, a sort of triangular duel always going on among the ivory dentists, mineral dentists, and vegetable dentists, each class fighting stoutly against both of the others.

Whether your dentist really makes the teeth which he inserts in your cranium, is a question he does not deem it necessary to answer. In truth, he very rarely does anything of the kind. There are certain dealers who sell sets of teeth, half-sets, twos or threes, singles or doubles, front or back, top or bottom, finished or unfinished; as well as all the apparatus and tools required for the dentist's art. And some of these dealers themselves are supplied by manufacturers, who conduct operations on a considerable scale. There is one firm in the metropolis at the head of the trade, who built a really beautiful factory a few years ago, replete with steam-engines, tooimaking shops, and all the appliances for a well-organized staff of two hundred operatives. How many incisors and canines, premolars and true molars, such an establishment can turn out in a year, we will leave Cocker to calculate.

Our American cousins, it appears, are not at all behind us in this art; while they are, perhaps, still more ready than ourselves to apply steam-power to its development. A recent computation makes the number of artificial teeth fabricated in the United States as high as three millions annually—symbols (according to some folk's notions) of three million attacks of toothache. In one of the largest and most complete factories, where mineral teeth are made, the chief ingredients comprise felspar, silica, and clay; those of subsidiary character are sundry metallic oxides, to produce those tints of discoloration which are necessary to make the imitation

a good one. The felspar, silica, and clay are ground to an impalpable powder under water, then dried, and made into a paste. The teeth are cast in brass moulds, varied in size and shape to suit the requirements of the mouth. A special kind of paste, to form the enamel, is first put into the mould with a small steel spatula; the platinum rivets, by which the teeth are to be fastened, are adjusted in position; and then the paste forming the body of the tooth is introduced until the mould is filled up. Next ensue powerful pressure and drying. When removing from the mould, the tooth goes through a process called biscuiting (analogous to a particular stage in the procelain manufacture), in which state it can be cut like chalk. It is then sent to the trimmer, who scrapes off all roughnesses and unnecessary projections, and fills up any depressions which may have been left in the operation of moulding. A wash called enamel is made, by selecting various ingredients more fusible than those of the tooth, grinding them to a fine powder with water, and applying the thick liquid as paint, by means of a camel-hair pencil. The tooth then goes to the glimmer, who applies a gum comprising oxide of gold and other ingredients. At length heat is applied. The tooth,' when dried, is put into a muffle, or enameller's oven, where it is placed on a layer of crushed quartz strewed over a slab of fireresisting clay. After being exposed for a time to an intense heat, the tooth is taken out, and cooled—and there it is, Beautiful for Ever.

St. Paul's. THE PLANET OF LOVE.

The contrast between Venus and Jupiter (two orbs which at one time during the past spring seemed so strikingly alike that only their position distinguished one from the other) is in reality most complete. It was difficult even for the astronomer to realize the fact that of those orbs one was thirteen hundred times larger than the other, that the surface of the lesser was illuminated some fifty times more brilliantly than that of the farther and greater. It required, too, a strong effort of the imagination to picture to oneself how one orb was solitary, like -Mars or Mercury, while the other was the

centre of the most symmetrical system of orbs within the planetary scheme.

It may be interesting to consider some of the facts which astronomers have learned respecting the beautiful planet which appropriately bears the name of the loveliest of the heathen goddesses. There is much, indeed, in what is known about Venus which rather tends to disappoint than to satisfy the questioner; much also which is more fitted to invite speculation than to afford any basis for sound theorizing. When we compare what has been learned about Venus with the detailed information which the telescope has given us respecting Mars, or with the grand phenomena whose progress has been traced in the distant orbs of Jupiter and Saturn, we are apt to feel astonished that the planet which approaches us most nearly should have revealed so little, even under the most searching scrutiny. Yet it is only by comparison with what has been learned about these most interesting orbs, that our information about Venus seems small in amount. In reality there is much that will very well repay our attention, more especially when we consider Venus, not merely with reference to what the telescope teaches respecting her, but also in relation to her position in the scheme of worlds circling around the sun.

It used to be supposed that Venus is rather larger than our own earth. But more careful measurements made in recent times have shown that she is in all probability considerably smaller than the earth. A circumstance had tended to deceive the early telescopists. Venus shines with such exceeding brightness as to appear larger than she really is. The fact that bright objects are thus seemingly enlarged is doubtless familiar to most who read this paper. It is strikingly illustrated by the appearance which the new moon presents when the unenlightened half of her globe is visible, or when "the old moon is in the new moon's arms." The dark part appears to belong to a smaller globe than the bright crescent; yet in reality of course the effect is but an optical illusion. Indeed, quite recently, astronomers had to reduce their estimate of the moon's mass on account of the very effect I am here referring to. In the case of Venus the effect is, of course, more remarkable, especially when considered with reference to the estimate of Venusjs bulk; for she shines much more brilliantly (though of course giving out very much less light altogether) than the moon; and being so much farther away, the same amount of seeming extension outwards corresponds in reality to a much greater error in the estimated diameter. Thus it happens that in Ferguson's astronomy we find the diameter of Venus set down at 7,906 miles, while Sir W. Herschel and Arago set it at 8,100 miles; whereas the estimate now generally regarded as most trustworthy assigns to her a diameter of only 7,500 miles. Thus her estimated bulk has been very considerably diminish

ed; for though her diameter has been reduced but by about one-sixteenth part from Ferguson's estimate, it is easily calculated that her volume has been reduced by fully a seventh part—in which degree it falls short of the earth's. Her surface, which is perhaps a more important feature when we consider her as the probable abode of living creatures, is less than the earth's in the proportion of about nine to ten.

Still, it is hardly necessary to point out that these differences are very slight when compared with those which distinguish the other planets of the solar system from our own earth. Mars, with his diameter of but 4,500 miles, on the one hand, and Uranus, with a diameter of more than 35,000 miles, on the other, seem startlingly unlike our earth after the relations of Venus have been considered; and yet they come next to her in this respect. We have to pass from Mars to small Mercury and the asteroids in following the descending scale of magnitude, and to pass from Uranus to Neptune, the ringed Saturn, and the mighty mass of Jupiter, in following the ascending scale. In the whole range of planetary bodies, from Jupiter, more than twelve hundred times bulkier than our earth, down to the least asteroid —a globe, perchance, not larger than Mr. Coxwell's balloon—we meet with not one orb which can be regarded as our earth's twin-sister world, save that globe alone whose glories now illuminate our evening twilight skies.

In one respect only the comparison fails. Unlike our earth, Venus has no moon. I shall not enter here into a consideration of the very singular circumstance that many observers, and some of them not unknown for skill and clearsightedness, have declared that Venus has a moon, and that they have seen it. Astronomers are now agreed that these observers were deceived, and I suppose little doubt can remain in the minds of all who are competent to weigh the evidence, that Venus has no satellite. Still there are few chapters in the history of astronomy more suggestive than that referring to the supposed discovery of a secondary orb, which has, in reality, no existence. Sir William Herschel's temporary belief in the existence of two rings at right angles to each other around the planet Uranus can by no means be compared with the strange deception which deluded observers in the case of Venus. For Uranus is so far off that his phenomena are seen only with extreme difficulty; and the telescope with which Sir William Herschel chiefly studied the planet was notoriously imperfect as a defining instrument, notwithstanding its wonderful light-gathering power. It. ■'bunched a star into a cocked-hat," we are told, and in effect it made the rings round Uranus which for a time perplexed the great astronomer. But in the case of a planet so near to us, and so bright as Venus, one would have thought an optical illusion, such as the telescopic creation of a satellite, was wholly impossible. Here was an orb of which its observers felt able to say that its diameter was about onefourth of Venus's, its light slightly inferior to hers in brightness, and its seeming shape horned, or gibbous, exactly as her own at the time of observation. And yet that orb was a mere moon-ghost, an unreal telescopic vision.

We shall inquire farther on, however, whether the want of a moon necessarily renders the skies of Venus at night dark and gloomy by comparison with ours, or, at least, with our moonlit nights.

The chief difficulty which the telescopist meets with in trying to examine the surface of Venus arises from the excessive brightness with which she is illuminated. Of course, I am here referring to quite another matter than that splendor which the unarmed eye recognizes in her light. Jupiter, when seen on the dark background of the midnight sky, shines with a splendor fairly comparable with that of Venus ; and yet rather the defect than the excess of light is what troubles the astronomer in the case of Jupiter. I am referring now to the intrinsic brilliancy of the illumination of Venus's surface—this brilliancy depending on her nearness to the sun. The degree of her brightness may very well be illustrated by an example. Suppose the side of a hill to be so sloped that the sun's mid-day rays fall square upon it. Now, if the slope is covered with white sand, it will shine rather less than half as brightly to the eye as the disc of Venus.* But we know how daz

* This is easily proved. We may be certain that the reflective capacity of Venus's surface is not less than that of the surface of the ruddy Mars, Now Zollner has shown that Mars reflects

zling white sand looks when the sun shines full and squarely upon it; so that it will readily be conceived that the disc of Venus tests the performance of even the best telescopes. For it is to be noticed that although the astronomer can cut off a part of the light by suitable contrivances, yet these must needs impair to some degree the clearness of the definition. Besides, some features may be wholly obliterated by any contrivances for reducing the planet's lustre, precisely as the dark glasses used in observing the sun blot from view altogether the colored prominences and the sierra which really surround his disc.

But, although Venus is thus rendered a difficult object of study, there is one feature'in her telescopic aspect which seems to place it in the power of observers to learn more about her surface-contour than even about the details of the planet Mars. Venus travels on a path inside the earth's. Hence she lies, at times, nearly between the earth and the sun, so that her dark half is turned towards us; while at other times she lies directly beyond the sun, so that her illuminated half is turned towards us. Obviously in one case she is presented as the moon at "new," while in the other she is as the moon at "full;" nor does it need much consideration to show that, in passing from one phase to the other, she must exhibit all the changes of aspect which we recognize in the moon. With, however, this further peculiarity, that whereas the moon remains always of about the same seeming size while passing through her phases, Venus, on the other hand, changes most notably in size, as seen in the telescope. When she is directly beyond the sun her distance from us is 66 millions of miles greater than the sun's, or about 157 millions of miles in

rather more of the sunlight which falls on him than he would if he were a globe of white sandstone. Supposing Venus to do likewise, then as she is so near to the sun as to receive twice as much light as the earth does (surface for surface), her disc must look rather more than twice as bright as white sandstone fully and squarely illuminated. In all such cases (be it noted in passing) distance has no effect. Distance may diminish the brightness of objects seen through air, or other imperfectly transparent media; and of course distance diminishes the total quantity of light received from an object. But distance in no way affects the intrinsic lustre of bodies seen through vacant (or practically vacant) space.

all. When she is directly between us and the sun, her distance falls short of his by 66 millions of miles, or is reduced to about 25 millions of miles. Her distance in the latter case is less than one-sixth of that which separates her from us in the former case; and her disc is more than 36 times larger. So that as she passes from new to full she is at once crescent and waning. Her orb is becoming larger and larger, while a continually diminishing proportion of it is illuminated. In passing away from full to new she decreases in seeming size, while waxing in the sense in which we use the term when speaking of the moon. The reader will doubtless remember how the discovery that Venus actually changes thus in seeming magnitude and phase was among the earliest which Galileo affected by means of the telescope. That his priority might not be questioned he announced the discovery anagrammatically in the following sentence—" Hnec immatura a me jam frustra leguntur, d.y.," which is very bad Latin for the statement that "These matters still immature, and as yet (studied) in vain, are read by me." Four months later he published the key to the anagram in the following much more elegant piece of I.atinity—" Cynthiaj figuras semulatur mater Amorum," or " Venus, the Mother of the Loves, imitates the changing figures of the moon."

Now when Venus presents her full face towards us she is much too far off to be well seen, and besides she lies directly beyond the sun, and his light prevents us from seeing her. On the other hand, when she is nearest to the earth, her dark hemisphere being turned towards us, she would be invisible even were she not in this case also lost in the sun's light. When she is best seen she presents much less than a full disc; and, in fact, she is actually best placed for study when showing a crescent phase, somewhat like the moon's two days before she is half full.

At first sight it might seem that this should render the study of Venus even more difficult than any of the circumstances yet named. The central part of her disc, just that portion which is alone unforeshortened, can only be seen when Venus is much farther off than Mars is at his nearest—when, also, he is most favorably seen in other respects ; while the portion seen when Venus is nearer is seen

edgewise, and therefore very unfavorably placed for study.

But in one respect there results a means of studying Venus which is wanting in the case of Mars. I refer to that very means whereby astronomers have been able to measure the height of the lunar mountains. The boundary between the light and dark parts of the moon is the region where, as seen from the moon, the sun is rising or setting. The mountain tops near that boundary catch the sun's light earlier in the lunar morning, and later in the lunar evening, than the plains and valleys close around. Precisely as the traveller who views the phenomena of sunrise from the summit of the Rigi or Faulhom,* sees the valleys still enshrouded in gloom, while the mountain tops are all illuminated; so out yonder, on our satellite, if there are living creatures there, contrasts of like sort, but much more marked, may be witnessed by such Lunarians as care to climb the summits of the peaks around such craters as Tycho, Kepler, and Copernicus. The telescopist can see the lunar mountains lit up by the sun's rays, when the valleys around are in darkness; for, outside the boundary line, between the light and the dark portions, he sees spots and streaks of white light, which he recognizes as the peaks of lunar mountains, or the summits of mountain ranges. And, by measuring the distance at which a lunar peak, which has just caught the light, lies from the boundary between light and darkness— or, as one may say, by measuring how far off the tiny island of light is from the shore-line—he estimates the height of the lunar mountains.

In Venus, similar phenomena are presented. Only her greater distance renders it less easy to study them to advantage. Of course if the planet were a perfectly smooth globe the boundary between the light and dark portions would be quite smooth and uniform. But as early as the year 1700, La Hire could recognize irregularities in the boundary, when the crescent was very narrow. But we owe to the German astronomer, Schriiter, the first satisfactory study of these irregularities. Towards the close of the last century he studied the planet with seve

* One is willing to believe that there are travellers who have been so fortunate.

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