MOD
MOD
All entrochi have a central cavity, or hollow, running thro' the whole length; and they are of different fpecies, according to authors, as this cavity differs in fize and figure. It is fometimes a mere point in the center of the ftone, and fome- times takes up a third part or more of its bulk. In (bme places there are indeed found entrochi which are perfectly hollow, being only a thin cruft ; of thefe, fome are perfectly fmooth and even on the furface, and others are in the common way, made up of rings, or marked with deep circular furrows. The hole in thofe Modioli which arc thicker, is fometimes round, fometimes formed like a cinquefoil-leaf ; but this laff is more rarely met with, and is called by fome of the later writers on foflHs, entrocho-ajieria, the ftarry cntrochus, to diftinguith it from the common kind. The roots, as they are called, of the entrochi have very often a configuration which leads to this i they have ufually five feet, and from each foot there palles in- wardly a little furrow to the top of the Hone. This may very Well give birth to the five enlargements of the central hollow in the others, and make them entroxho-sfieriee. 1 here is a fcarce fpecies found fometimes on Mendip-hills, which has i\x hollows inlfead of the five of the other, and thefe all terminate in angles, fo that the whole is a fexangular hollow, whereas the cinqucfoil inlets are ufually round as the leaf whofe name they bear, tho' fome few of them have fharp angles. Phil. Tranf. N\ 129.
'I he joints and lockets by which the entrochi are joined toge- ther are very various, for as feveral rays (hooting trom a cen- ter mull of neceffity have confiderable widenefles between them, as they pafs toward the circumference, according to the bignefs ; fo to fill up thofe wide (paces in fome, between two rays there iffues from the center a third ray, which palles as the others to the circumference of the ffone. Some have their rays gently widening from the center all the way to the circumference : In fome, between two forks, made by a ray that parted fingle from the center but divides afterwards, there rifes alfo a little ray which runs to the circumference : And fome others are ramofe, having a trunk rifing from the center, with three, four, or five branches, running to the circumference : Some alfo are fmcoth half way of the ftone from the center, and have a circle of fmall rays near the cir- cumference ; and fome are perfectly fmooth, and have no rays at all. Thefe are ufually very thick, and are joined together in the entrochus after this manner : One trochite, or iimple modiolus, a little within the outer circle, in the upper and lower parts, where the rays ufe to be, has round inlets or fockets confiderably deep, fo that only a thin tympanum hin- ders the trochite from being hollow at this width all through ; and in the middle of this tympanum there is a hole as in the other trochitse, which is fometimes round, and fometimes of a pentangular figure. The trochites that anfwer this, have fmooth joints on both fides, without any fkrew-like ridges entering into thefe fockets, thofe joints being hollow alfo; and fo other trochitse with fockets come on again upon thefe; and thus the entrochus is made up. Some of thefe Modioli have both fockets and rays, and fome have a fockct alone on one fide, and rays without a focket on the other. Finally, fome are perfectly fmooth, only that a fmall ridge runs round them, a little within the outer circle, which enters into a fmall furrow anfwering to it ; and fome are fmooth and joined only fir harmonium. Some of the trochita: hold of an equal thicknefs from the center to the Circum- ference, and others are confiderably thick at the circum- ference, and thence grow gradually thinner to the central ca- vity, at the verge of which, all round, they make a fort of edge. Thefe have concavities on both fjies, to which convexi- ties in the adjoining trochitrc anfwer :' Some hold of an equal thicknefs half way from the circumference toward the center of the Hone, but they then grow thin, and continue fo to the very verge of the cavity.
Befldethe generality of thefe trochitse which are round,thereare others found which are of an oval figure, fome rounded at the ends; and fome pointed ; thefe have their central cavity as well as the others, and fome have it very fmall, others very large. In thefe it is always oblong, according to the fhape of the ftone, not round, as in the round ones. Thefe ufually are not joined in the cntrochus by means of rays, hut have a ridge running all along the verge' in one, which is received into a furrow in the other. Some of thefe joints are fhaped with a double oval, the oval of the upper part of them Handing contrary to the oval in the lower : in others, the ovals do net ftand fo entirely oppofite one to another, but only the oval in the upper part feenis a little wrefted from the dircfl line of the oval of the lower part, fo that they ftand bendwife to each other, and make up a figure like a St. Andrew's crofs. There are entrochi made up in this manner, and it is in ge- neral obferved, that molt of the oval entrochi grow crooked and twilling. Thefe oval ones are found lefs frequently in the entrochus flute, than in the fingle trochites ; but they are fometimes met with, and are liable to all the accidents in fi- gure and furface of the common round ones. The obfer- vations of the manner of joining of the feveral trochita; into the entrochus, and of the rays and fpaces, with the manner of filling- up the latter, and the various divarications of the for- mer, area very pleading obligation; but it is neccflary, in
many cafes, to have recourfe to the afliftance of glaffes for the perfectly underflanding them, the naked eye loling a great part of the ftructure. MODIRA Kaniram, in botany, a name given by fome authors to the tree, whofe wood is the lignum colubrinum, or fnake- wood of the fhops. Hort. Malah. vol. 8. p. 47. MODULUS of the logarithmic Syjlem. See the article Loga- rithm. MOFFAT Waters, mineral waters of confiderable efficacy at Moffat, in the county of Annandale. They arife from two fprmgs on the declivity of a hill, which yield about 1360 gal- lons of water daily. Thefe waters have a fulphureous tafte, and fmell of the walhings of a gun-barrel ; their colour is milky or bluifh. The feafon for ufmg them is between the middle of April and the end of September ; but they may be drank all winter, and if the rains be moderate, the ftrength of the water is not found to be impaired. The water of the upper fpring being too foul for drinking, is made ufe of for bathing, and is, for this purpofe, made fomewhat warmer than tepid. The quantities of water ufually drank are pretty large, exceeding fometimes a gallon. It is ufual to join pur- gatives, and that in great dofes, frequently repeated with the ufe of the waters ; but this is thought unjuftifiable by fome K The water is alterant and diuretic. Its purging is owing to the large quantities drank, or to fome fingularity in the con- ftitution, as a weak ftate of the ftomach and interlines. Few medicines are faid to be fuperiorto thefe waters indiforders of the ilomach and bowels. It has alfo proved ufeful in nephri- tic, nervous, and hyfteric colics, melancholy, barrennefs, female weaknelfes and diforders, as alfo in old gleets, either natural, or caufed by venereal diforders. In rheumatic and fcorbutic complaints it is advantageous, and in cutaneous eruptions. It is faid feldom to fail in fcrophulous diforders b . This water gives no marks of a chalybeat nature with galls, nor of acidity with tincture of rofes, or fyrup of violets, nei- ther does it produce any effervefcence with oil of tartar per de- hquium, or fpirit of fal ammoniac. It feems to contain a fub- til volatile fulphur, but in fmall quantity, fince it foon lofes its remarkable fmell and tafte, when expofed to the air, and that acid liquors can neither feparate nor precipitate it. Upon evaporation there is found a dirty fait mixed with earth. This fait feerhs not to be nitre, nor fal ammoniac, but com- mon fait, and by a flow evaporation of a folution of fea fait, cryftals not unlike thofe of the fad of Moffat water have been obtained . — [» Medic. Elf. abr. vol. 1. p. gg. i> Ibid. p. 101. e Ibid. p. 103. feq. where other experiments on thefe waters may be feen.J
MOGORIN, in botany, a name given by the Portuguefe to an Indian or Chinefe flower, growing on a fmall fhrub. It is of a wonderful white colour, and not unlike the gin-feng, only that it abounds more with leaves, and fmells much fweeter; one fingle flower filling a whole houfe with its odoriferous effluvia. On this account the Chinefe put a high value upon it, and carefully defend the fhrub it grows on from the inclemency of the winter, by covering it with vafes provided on purpofe. Hofm. Lex. in voc.
MOHAUKS Corn, in botany, a name given hy the Indians to a peculiar fort of the maiz, or Indian corn. It is moft fre- quent in the more northerly parts of America. The general time of lowing the maiz in Virginia and other places, is in the end of April ; but this Mohauk kind need not be fown be- fore June, and yet will come well to maturity before the win- ter. The ftalks of this kind are fllorter than thofe of the common fort. The ears alfo are fhorter, and grow nearer the ground, and the corn is generally of various colours. Phil. Tranf. N '. 142.
MOIRE, in conchyliology, the mohair fiiell, a name given by the French virtuofi to a peculiar fpecies of voluta, which feems of a clofely and finely reticulated texture, and refembles on the furface a piece of mohair, or a very clofe filk-worms web. See the article Voluta.
MOISTURE {Cycl.)— The Moijlure of the air has confiderable effects on the human body. For the quantity and quality of the food, and the proportion of the meat to the drink, being given, the weight of a human body is lefs, and confequently its difcharges greater in dry weather than in wet weather ; which may he thus accounted for : The Moijlure of the air moiftens the fibres of the (kin, and leffens perfpiration, by leffening their vibratory motion. When perfpiration is thus leffened by the Moijlure of the air, urine, indeed, is by degrees increafed, but not equally. See Dr. Bryan Robinfon's Dill', on the Food and Difcharges of human Bodies, p. 68. feq.
Hence we learn, that to keep a body of the fame weight in wet weather as in dry, either the quantity of food muft be leffened, or the proportion of the meat to the drink increafed ; and both thefe may be done by leffening the drink, without making any change in the meat.
MOLA, (Cycl.) a mole, or falfe conception, in medicine, is a membranaceous and fibrous concretion in the womb, contain- ing ufually a large quantity of coagulated or thick blood. This is fometimes produced alone in the uterus, fometimes at the fame time with a regular fcetus. There are many origins to be afligned to thefe concretions, but the mod ufual feems to be
the
