QUARANTINE, a word denoting the period of restraint, formerly forty (quaranta) days, to which ships' crews are subjected when infection is presumed to be amongst them. QUARTAN, a fever or ague, of which the paroxysm recurs every fourth day. QUARTO, a term for that size of books formed by dividing a sheet into four leaves. QUARTZ, a species of stone, often found in pure white crystalline masses, and sometimes endowed with various tints by other minerals, as in the case of amethyst, which is a purple quartz. QUININE, a bitter alkaline body, extracted from Peruvian bark, and much used as a tonic in the form of sulphate. QUOTIDIAN, an intermittent fever, of which the fit occurs once every day. RADIAL and RADIATED, adjectives applied to bodies of a figure resembling in whole or in part a cart-wheel, of which each spoke is a radius or ray, such being the name given to lines passing from the centre to the circumference of every circle. RADIX, a root. RAMADAN, a solemn fast kept by the Mahometans during the ninth month of the Arabic year, and lasting, each day, from dawn till sunset. RATIO, the proportion of one thing in regard to any other thing. REBUS, properly a species of riddle, in which some name or word is represented by figures or pictures. RECIPE, a receipt or prescription. RECITATIVE, a kind of musical composition, in which the accentuations of common speech are imitated. RECTANGLE, a right angle, or angle formed by two sides which are perpendicular to one another. RECTUM, the terminating section of the intestines. REGATTA, a word adapted from the Italian, and plied to boat or yacht races. SACRUM, the small terminating bone of the bone. SALIQUE, the title of the old law of France, excluded females from the throne. SALIVATION, an increased flow of saliva fram glands of the mouth, caused by medicines. SANHEDRIM, a word signifying the great publier cil, civil and religious, of the Jews. SANSCRIT, the old or dead tongue of Hindostur which much valuable learning is contained. SAPPHIC, a species of verse among the Greeks Romans, consisting of four lines, and named Sappho." SARCOPHAGUS, a word applied to tombs, and der from the body-consuming effects of a species d stone which was anciently used for making coffies. SCAPULA, the shoulder-blade. SCARABEUS, the beetle. SCROFULA, a disease consisting in hard tumours the glands, chiefly of the neck. SENSORIUM, the brain or centre of nervous including sensation and volition. SEPTIC, anything that promotes putrefaction. septic signifies any thing that checks it. SEPTUAGINT, a Greek version of the Old Testa named from its being executed by seventy (septua Jews, or perhaps seventy-two. SERRATE (or SERRATED), something notched like SERUM, a very thin and transparent fluid, a lubricates those surfaces in the interior of the which do not communicate with the external air. SETON, an issue on the body, formed by the insura of a cord. SIDEREAL, of or pertaining to the stars. SIENITE, a compound, granular, greyish-tinted : named from Siene in Upper Egypt. SIERRA, a Spanish name for an eminence or cha ap-hills. REGIMEN, a regulated course of diet in medical language. RELIEVO (or RELIEF), a word applied to that mode of sculpture or carving in which figures are raised more or less from the surface. RETINA, an expansion of the optic nerve, on which external images are cast, and through which ocular perception is effected, the other parts of the eye being strictly mechanical. RHETORIC, the art of speaking with propriety, elegance, and force. RHOMBOID, a four-sided figure, of which the opposite sides and angles are equal, but which is neither equalsided nor right-angled. RHOMBUS (or RHOMB), a four-sided figure with equal sides, but not right-angled; as, for example, a carddiamond. RHYTHM, the measured division of time in music, or in verses of poetry. RIFACCIMENTO, a word from the Italian, signifying something dressed up anew. RONDEAU, a short species of poem with few rhymes, in which the sense of the opening lines is repeated, or nearly so, at the close. ROSICRUCIANS, a sect of mysticists of the middle ages, who called themselves Brethren of the Rosy Cross, and prosecuted in secret the search for the philosopher's stone and the elixir of life. ROUND-ROBIN, a mode of addressing or petitioning, in which, to prevent any subscriber from seeming more forward than another, the names are arranged in a circle. RUNIC, the title of the characters forming the language of the ancient Scandinavians or northern Goths. SABBATICAL, an epithet given to every seventh year in the Jewish economy, because they then allowed their to rest without tillage, and gave external nature bbath. INE, of or pertaining to sugar. SILICA (or SILEX), a primitive earth, the main c tuent in all stones and rocks whatsoever. SINAPISM, a mustard poultice. SIPHON, in hydraulics, a tube from which the.” extracted for the purpose of raising fluids, by the at spherical pressure behind, above the level of the r voir. SMELTING, the art of fusing ores for the extract the metallic parts from the refuse. SOLECISM, in grammar, a violation in one way another of the rules of the art. SOLSTICE, the term assigned to the two peri which the sun enters the tropics of Cancer and corn, which is respectively on the 21st of June az 21st of December. SOMNAMBULISM, a word denoting the act or p menon of sleep-walking. SOPHISM, a false species of reasoning, not sup by the premises. Sophistry is the art or pract using sophisms. SOPORIFIC, an epithet for any thing inducing slee SOPRANO, in music, a term applied to a spec treble, suited to the female voice. SPECIFIC, in medical language, a remedy which any special disorder with more than common certa SPECTRUM, a bright spot formed by admitted iz any surface, or the image of an object seen after eye is withdrawn from it. SPECULUM, in optics, a polished body impervi light, or which reflects it. SPHEROID, a body nearly approaching a sphere inst SPONDEE, a poetic foot, or division of a line, cons of two long syllables. SPORADIC, an epithet opposed in sense to epider and signifying diseases which are neither genera contagious. STALACTITE, a name for the concretions forme carbonate of lime, which accumulate in consequen the drippings from the roofs of caverns. STAMEN, one of the two main parts of fructification -" plants. STANZA, a word now used to designate every portion a poem united by rhymes. TARIFF, a table of the customs or duties chargeable upon goods. TARSUS, the bones of the foot immediately adjoining the heel. STATISTICS, a science of a comprehensive order, emracing every thing connected with the population of a ountry, their condition and employments. STEARINE, the solid constituent of oils and tallow. STENOGRAPHY, the art of writing in short-hand. STEREOTYPE, a solid plate of metal, cast from a prearation of stucco, and receiving from it an impression f drawings or letter-press, previously communicated | y common gravings or types. The art of stereotypg is now of great use in giving to publishers permaent impressions of their works. STERTOR, a noisy kind of breathing, following affec-strument through which distant objects are viewed. ions of the brain. TAUTOLOGY, the needless repetition of the same words or ideas in speech or writing. TECHNOLOGY, a treatise on the arts; a word derived from techné (art), and logos (a discourse). The epithet technical, denoting something belonging to art, is from the same source. STETHOSCOPE, a tubular instrument, by applying the ar to which internal diseases of the chest or abdomen re discovered. STIGMA, in botany, the top of the pistil into which the ollen is received. STRABISMUS, in technical language, a squint. STRATIFICATION, the process by which any portions f the earth have been arranged in layers or beds, alled strata. Generally speaking, all stratified rocks ave been subjected to the influence of water, while nstratified rocks are more or less volcanic in their rigin. STRIATED, streaked or marked with lines. STROPHE, the first division of a Greek ode, succeeded STRUMOUS, an epithet applied to glandular tumours. SUBSTRATUM, any substance that underlies another SUCCEDANEUM, anything which serves as a substi TELEGRAPH, a word signifying "writing to or for a distant point, and applied to the various inventions by which news are communicated between distant spots by flags or other means." TELESCOPE, a term signifying and applied to an in TENTACLES (TENTACULA), the organs of feeling, prehension, and motion, in various insects and other animals, and sometimes viewed also as organs of hearing. TERMINOLOGY, that branch of philological science which explains the sense of terms of art. TERRA-COTTA, an Italian word signifying baked clay, and applied to a class of relics of art, such as vases and the like, formed from that substance, and found in considerable quantities in Tuscany. TERTIAN, an ague of which there are two paroxysms every three days. TERTIARY, a term used to denote the later formations in the earth's crust, comprehending the superficial alluvial deposits, and such as are composed chiefly of sand and clay. TESTACEOUS, a word given to animals which have a strong thick shell, such as oysters, and are included in an order called by the general name of testacea. TESTUDO, the tortoise tribe of animals. TETANUS, a word usually applied to locked-jaw by medical men. THEISM, the doctrine of the existence of a God, opposed directly in sense to atheism. THEOLOGY, literally, a discourse on divinity, and commonly denoting the study or science of religion. THEOREM, a speculative proposition deduced from several definitions compared together. THERAPEUTICS, a term applied to the study of the symptoms of disease and its remedies, and denoting, in short, the healing art generally. THERMAL, an epithet equivalent to warm or tepid, and usually assigned to mineral waters so characterised. THERMOMETER, an instrument for measuring heat by means of a graduated scale of degrees. THESIS, a theme or proposition advanced and maintained by illustration and argument. THORACIC, of or pertaining to the thorax or chest. TONICS, medicines which increase or restore the healthy tone of the coats of the stomach and muscles generally. TOPOGRAPHY, a description of places, or minute branch of geographical science. TORNADO, a whirlwind. TORSO, the trunk of a statue deprived of head and limbs. TOURNIQUET, a surgical instrument for repressing the flow of blood. TOXICOLOGY, a treatise on poisons, or the science which takes cognisance of them. TRANSCENDENTAL, the philosophy of pure or speculative reason, which occupies itself not so much with objects as with the way of knowing them. TRANSITION, the term applied to those parts of the earth's crust supposed to have been arranged when the earth was passing from the uninhabitable to the habitable state. TRANSUBSTANTIATION, the conversion of the sacramental bread and wine into the body and blood of the Saviour, held by Roman Catholics to take place in reality. TRAP, a dark semi-volcanic rock, usually found in a stepping-stones. columnar form, or arranged in successive layers like TRAPEZIUM, a geometrical figure having four unequal sides. TRAVESTIE, a burlesque imitation of grave writing. TREPANNING, in surgery, an operation by which the skull is perforated in order to raise a depressed portion. TRIGONOMETRY, the art of measuring the sides and angles of triangles. TROCHEE, a poetical foot of two syllables, one long and the other short. TUBERCLES, in anatomy, small round suppurative tumours, such as those affecting the lungs in consump: tive disease; the adjectives tubercular, tuberose, and tuberous, are applied, in medical and botanical language, to denote the presence of knobs or growths so shaped. TUBULAR, having the form of a tube. TUMULUS, a barrow or mound of earth or stones formerly erected over the dead. TUNICATED, covered with one or more tunics or coverings. TURBINATED, in conchology, a term applied to any shell wreathed serpentinely from a broad base to a narrowed apex. TURBINITE, a fossil turbinated shell. TUSCAN (ORDER), an ancient, massive, and simple style of architecture. TYMPANY, a flatulent distension of the abdominal region. TYMPANUM, the drum of the ear, or strong partition dividing the outer from the inner parts of the organ of hearing. TYPHUS, a dangerous species of continued fever of a contagious nature, and marked by a tendency in the system to putrefaction. TYPOGRAPHY, literally," writing with types," or the art of printing. VENTRICLES, a name given to cavities in the br and brain. VENTRILOQUISM, a word signifying "speech fre stomach," and erroneously used to denote the ar which the voice is made to appear as if it came * different places-an art dependent on skilful : ment of the voice in the windpipe, and other means of illusion. Ventriloquism, in short, sor consist simply in vocal mimicry of a very perfect. VERMICULAR, of or belonging to worms, ca. 4 vermes in the Linnæan classification. VERMIFORM, shaped like worms. VERTEBRA, the twenty-four strong and united which form the spine or vertebral column, and the trunk and head. VERTEX, the top or summit of any thing; w the adjective vertical, applied commonly to a placed or rising directly upwards in the air or vens. VIADUCT, a carriage-way, raised or arched ov hollow or low-lying spot. VILLOUS, Covered with down or soft hairs VIRUS, poisonous or corrosive matter. VISCUS, an organ in medical science. VITREOUS, a term signifying glassy, and af the soft pellucid humour filling the fore-partseye. VITRIFACTION, conversion into glass. VIVIPAROUS, a term applied to animals whic! forth living young, as opposed to egg-bearing tures. VOLCANO, in geology, a burning mountain er nence from which ignited and melted matters ar forth. Volcanoes have evidently been instrume moulding a great proportion of the existing er the globe. Traces of them, in an extinct stak, a ULTRAMONTANE, a term signifying "beyond the moun- noticed almost everywhere. tains." UMBILICAL, of or pertaining to the navel. VOLTAIC PILE, the upright series of alternate and silver plates, which the chemist Volta fort: UNCIAL, an epithet for writing in which large cha- a mode of developing the galvanic power, after racters are used. UNGUICULATE, provided with claws or nails. URANOLOGY, a discourse on the heavens. URANUS, a name of the planet Herschel or Georgium Sidus. UTILITARIAN, an epithet first applied to the followers of Jeremy Bentham, or those who estimate all things by their degree of usefulness in promoting "the greatest happiness of the greatest number." UVULA, a small dependent body at the back of the mouth, familiarly called the pap of the throat, and useful as a sort of defence to the tops of the windpipe and gullet. VACCINATION, the operation of introducing cow-pox matter into the human body, in order, by producing a greatly mitigated disease, to preserve the system against natural small-pox, which rarely occurs twice in one person. From noticing that cow-milkers were strangely free from liability to small-pox, Dr Jenner discovered the invaluable secret that certain pustules on the udders of cows possessed the property described. VACUUM, a space named as being void or vacant, but always containing, in reality, some amount of highly rarefied air even under the most powerful air-pump. VARICOSE, an epithet for veins distended in an uneven or knotted manner. VASCULAR, provided with or pertaining to vessels. VATICAN, the title of a palace built on a hill of the same name at Rome, and containing the magnificent library collected by successive popes. covery by Galvani. The pile is now disused, £r. vanic trough being substituted for it, as mere and convenient. VORTEX, the centre of a whirlpool or whirlwa of any body or bodies in rapid circular commot VULCANIC, the title sometimes given to the the Dr Hutton, which ascribes almost all geological nomena to subterranean fire. WERNERIAN, a name for the aqueous theory of earth, or that which regards water as the chief p gical agent, derived from the German ph Werner. WRANGLER, a term applied to the successful er titors for degrees in the English universities, par larly in mathematical contests. ZENITH, that point in the heavens which is d above or vertical to the spectator, or to any given » of the earth. ZERO, the point of a thermometer from it is grade or the numbers are begun. Fahrenheit's zero is th degrees below the freezing point of water. ZODIAC, an imaginary belt or broad circular s the heavens, within which the whole of the pa make their revolutions. It is divided into twelve " of 30 degrees each, called the Signs of the Zodiac. named respectively from the constellations which observed to pass them. ZOOLOGY, the science which treats of the stru character, and varieties of animals or living create " ZOOPHYTES, a class of remarkable animals, ef sponges and corallines are specimens, and which semble plants, having stems more or less calcare and in which many of the animals are congregate.. VELOCIPEDE, a wheeled machine so constructed that TILATION, the free introduction of air into any Printed and published by W. and R. CHAMBERS, Edmi♫ŢA CHAMBERS'S INFORMATION FOR THE PEOPLE. CONDUCTED BY WILLIAM AND ROBERT CHAMBERS, EDITORS OF CHAMBERS'S NUMBER 96. NEW AND IMPROVED SERIES. THE STEAM-ENGINE. PRICE lid. HE apparatus which, after nume- WATER. Watt. The matter of which the external world is comosed presents itself to our notice in three palpable orms or conditions, namely, the solid, the liquid, and he aeriform. Stones or pieces of metal belong to the irst kind; water and quicksilver are instances of the econd; in the air, and in gases, such as carbonic acid tas, we find examples of the third. But all the different kinds of matter, whether simple or compound, are lot specially found only under one or other of these orms; for it may be truly said, that the solid, the luid, or the aeriform condition, is merely contingent, hat is, depending on certain circumstances besides the nherent nature of the particles of matter of which sach body individually is composed. Hence it is that the same kind of matter may, on changing those conitions referred to, assume first the solid form, then he fluid, and finally the aerial state; or, conversely, being in the aerial state, it may be rendered fluid, and astly become solid. James Watt, whose discoveries entitle him to be called the ventor of the steam-engine, was born at Greenock, in Scotland, January 19, 1736. At fourteen years of age he removed to Glas ow, and there, while afterwards acting as mathematical instrunent-maker, he began those great improvements on the steam ngine, which were completed in future years. Watt died on the 5th of August 1819. The law applies to bodies whether they are simple or compound, and is beautifully seen in the different forms which water assume when exposed to a varied range of temperature. For, below 32 degrees of Fahrenheit, it is solid (ice); between 33 and 212 degrees, it is fluid (water); and above 212 degrees, it is in the form of vapour (steam); changes in its physical form, immediately related to and connected with changes in the amount of heat with which it has been supplied. Water, which forms the grand agent in the steam-engine, is not a simple or elementary body, but consists of two distinct kinds of matter, the natural condition of which, when free under the ordinary circumstances of our globe, is that of an aërial substance. These two distinct matters, or substances, are oxygen and hydrogen; combined together in the proportion of one by bulk of the former, with two by bulk of the latter, they constitute the compound water, which had been, until nearly the close of the last century, considered as an elementary body. But water, as it is found in nature, though it is essentially composed of the matters now mentioned, does not consist solely of these, inasmuch as whether it be taken from springs, from lakes, from the sea, from rivers, from melted snow or ice, or from rain, or from any other source, it contains many other substances held in solution, and which affect its character very much-rendering it, indeed, often totally unfit for those purposes to which it is usually applied. When devoid of these substances, the water is considered by chemists as pure. The substances which are dissolved by the water, and which render it impure, are of two distinct kinds-solid matters, such as lime, magnesia, and iron; gaseous matters, such as the elements of the air, oxygen and nitrogen, and carbonic acid. The proportion of solid matter varies considerably. In the waters of the sea which surrounds our shores, the amount of solid matter is estimated at nearly about 34 per cent. Again, in river water, the proportion of solid matter is considerably less than that found in the sea. The quantity of gaseous matter varies, but not so much as that of the solid matter. In rain water, there in which the usual proportion between the oxygen and is usually noticed 24 per cent. of atmospheric air, but nitrogen is not preserved, as there is 32 of oxygen out of the 100, the remainder being nitrogen, whereas 21 is the proportion of oxygen in atmospheric air. Carbonic acid gas also is found in water. On boiling the water, these gaseous bodies are set at liberty, and pass off as gases. Also the solid substances, | 72 degrees, a temperature of the atmosphere fre such as the compounds of lime, are deposited, and form thick incrustations on the boiler, which require to be removed, otherwise it would be rendered totally useless. It is only the pure matter of oxygen and hydrogen -the actual water, as it may be termed-which is required in the working of the steam-engine; the other substances, whether aëriform matter or the solid particles held in solution, being not only useless, but even injurious. It will be seen that there are particular contrivances devised in the structure of the steamengine to remove these. Water is a fluid at ordinary temperatures, but may become solid on the one hand, or aëriform on the other, by changes in the amount of caloric (heat) with which it is supplied. These two remarkable changes in the condition of water occur at specific temperatures; it becomes solid when the degree of temperature indicated by the thermometer of Fahrenheit is 32 degrees, and passes off in the state of vapour or steam when the same thermometer indicates the temperature to be 212 degrees. On the fluid being cooled down to 32 degrees, it becomes ice, the temperature 32 degrees being named the freezing point of water. observed in the summer months of this country ether, which boils at 96 degrees, a temperature: corresponding with that of the human body lower only by 2 degrees), in vacuo would bri degrees below zero, or at a temperature lower that which would suffice to render mercury sal The thin aërial fluid called the atmosphere, or -monly the air, is a distinct material substanes rounding the globe, and possessing considerable That the air is actually a material substance, easily shown by connecting a thin glass flask, pr with a good stop-cock, with the exhausting tub air-pump. The air can in this manner be withd and the flask will be found to weigh less than b One hundred cubic inches of air, when perfect weigh, according to the very careful investigat Dr Prout, 31-0117 grains; the temperature of t being 60 degrees Fahrenheit, and the pressure air, as indicated by the barometer, being equa. * inches of mercury. If, instead of air (the oxygen and nitrogen whe stitute the atmosphere), an atmosphere of mercury-to envelop the globe, which would have the same as the air, it would be about 30 inches abov air, the fluid water were substituted, it would be 34 feet above the level of the sea. Hence, we r the pressure of the air is equal to a column of me 30 inches in height, or to a column of water 34 fæer : or, in other words, whatever extent of surface we the pressure of the atmosphere is equal to the pre or weight of 30 inches of mercury, or 34 feet of TM. over a similar surface. When the temperature is increased, so that the ther-level of the sea; and if, in like manner, instead mometer indicates 212 degrees, the water becomes steam or vapour, assuming that condition in which its elastic force is applied to act as a moving power. On the water passing off in this new form or condition, two very remarkable phenomena take place, namely, the fluid expands to a very great extent, the vapour occupying nearly 1700 times the space which the fluid occupied from which it was generated; and at the same moment, an immense quantity of caloric or heat enters into the water while becoming steam, and disappears; which heat, from the circumstance that it cannot be discovered by the thermometer, is usually called latent heat, in contradistinction to that which affects the thermometer, and which is accordingly named sensible heat, that is, heat whose effects are apparent in producing the movement of the fluid in the thermometer tube. When the water has assumed the state of vapour, it is invisible, being as perfectly transparent as the atmospheric air; and in this form it becomes obedient to those laws which affect gaseous or aëriform bodies, supposing always that the usual increased temperature is maintained (212 degrees Fahrenheit) to preserve it in this new state; for, on withdrawing the caloric, it then returns to its liquid inelastic condition, which is termed condensation. This elastic state of the vapour may be suddenly destroyed by bringing it in contact with a large quantity of cold water-a process essentially a part of the greater number of steam-engines. In this state of vapour the temperature is 212 degrees, or the same as that of the water from which it is generated. This may be easily determined by placing a thermometer in the boiling water, and then in the steam which arises from it. The amount of this pressure, estimated by the --of surface, is as 147 pounds on the square me nearly 15 pounds. In other terms, the weight pressing on a square inch is 15 pounds, and the of the column of mercury is 15 pounds, and the v of the column of water is also 15 pounds. That's column of air whose basis is exactly a square inė, tending from the surface of the globe to the high extreme range of the atmosphere (nearly 45 ma equivalent to the column of mercury which is m inches in height, or to a weight of 14-7 pounds, It is this weight, then, which the water has t come before it pass into vapour. The greatest pro of the atmosphere will be at the surface of the and as we ascend in elevation above the sea e pressure will gradually decrease, less air being 1. us, and in a corresponding ratio the volume will mented. By attending to these circumstances, we peres when the pressure is lessened, water boils at temperature than 212 degrees; and therefore, t have not merely to consider the temperature to the water is exposed, but also the amount of the of the atmosphere at the time, or the height of th== cury in the barometer tube. For example, at which is 10,000 feet above the level of the sea, *. boils at 194 degrees Fahrenheit, while at Geneva, lition begins at 209 degrees, that city being 12 above the sea level. Under the usual conditions in which water is made to boil, as in an open vessel on the fire, the temperature indicated by the thermometer is commonly about 212 degrees, the water acquiring at that temperature suffi- The law, then, as regards the pressure of the cient elastic force to overcome the weight of the atmosphere, simply is, that the boiling temperature » sphere. But it is to be observed, that the pressure of formly the same when the barometer is at the the air must tend to retard the water swelling out into height. If we employ the thermometer of Fabre vapour; it will follow, therefore, that if we reduce the it will be found that the boiling point is exer pressure on the surface of the water, the escape into degrees if the barometer indicate 30 inches; bat the state of vapour will take place at a lower tempera- boiling point rise to 213 degrees, then the barer ture, as was first observed by Dr Cullen, and subse- also will ascend to about 30; and conversely, quently more minutely detailed by the late Professor nearly 211 degrees, the barometer conversely a Robison. The latter has, indeed, established the general fall to about 294. It is obvious, then, from these " proposition, that vapours are produced from fluids in that the boiling point is an index of the height (where all atmospheric pressure is removed) at barometer, and, on the other hand, that the beg grees of Fahrenheit below the temperature at the barometer will give the point of ebullition ser hese fluids naturally pass into vapour, under the to the thermometer of Fahrenheit, or any other : essure of the air. Water, for instance, which may be used. boils at 212 degrees, in this case would boil at 10 Experimentally, the effect of a diminution of press.” |