Page:Cyclopaedia, Chambers - Volume 2.djvu/184

 MER

This is the Line of twelve a-clock 5 and from hence the Divifion of the Hour-Lines begins.

Meridian Magnetical, is a great Circle paffing thro' or by the Magnetical- Poles ; to which Meridian the Com- pafs (it not otherwife hindred) hath refpccl. See Mag- net and Compass.

Meridian Mtttudeof the Sun or Stars, is, their Alti- tude when in the Meridian of the Place where they are ob- ferved. See Altitude,

The Meridian Altitude may be defined an Arch of a great Circle perpendicular to the Horizon, and terminated between the Horizon and the Star then in the Meridiem of the place. See Sun, Star, Planet, &c.

To take the Meridian attitude of the Stars.

Aftronomers make two principal kinds of Obfervations of Stars j the one when they are in the Meridian, and the other when in Vertical Circles. See Observation.

For Meridian Obfervations $ there are two Inltrumeftrs principally ufed, the Quadrant and Gnomon. See Qua- drant and Gnomon.

To take the Meridian Altitude with a Quadrant ; if the Po- rtion of the Meridian be known, and the Plane of an Agronomical Quadrant be placed in the Meridian Line by means of the Plumb-Line fufpendedat the Centre : The Meridian Altitudes of the Stars, which are the principal Obfervations whereon the whole Art of Aitronumy Is founded, may eafily be determined.

The Meridian Altitude of a Star may likewife be had by means ofa Pendulum-Clock, if the exacl time of the Star's Paffage by the Meridian be known. Now it mult be obferved, that Stars have the fame Altitude for a Mi- nute before and after their Pailages by the Meridian, if they be not in or near the Zenith : But if they be, their Altitudes mult be taken every Minute when they are near the Meridian ; and then their greater! or leaft Altitudes will be the Meridian Altitudes fought.

As to the manner of Obferving, it is found very difficult to place the "Vane of the Quadrant in the Meridian exactly enough to take the Meridian Altitude of a Star ; for unlefs there be a convenient Place, and a Wall where the Qua- drant may be firmly tanned in the Plane of the Meridian, which is not eafily had, we ihall not have the true Pofition of the Meridian proper to obferve the Stars.

'Twill be much eafier therefore on feveral Accounts, to life the portable Quadrant, by which the Altitude of the Star may be obferved a little before its Paffage over the Meridian every Minute till its greatefl: or leaft Altitude be found. Here tho* we have not the true Pofition of the Meridian by this means, yet we have the apparent Meri- dian Altitude of the Star.

Tho' this Method, in the general, be very good, and free of any fenfible Error, yet in cafe a Star paffes by the Meridian near the Zenith, it proves fomewhat de- fective : For in thefe kind of Obfervations, the inconve- nient Situation of the Obferver ; the Variation of the Star's Azimuth feveral Degrees in a little time ; the Alteration of the Inttrument, and the difficulty of replacing it verti- cally, will prevent the Obfervations from being ofrner than in every four Minutes. But in each Minute, the Al- titude varies about fifteen Minutes of a Degree, fo that there will be the difference of a Degree in the Star's Al- titude between each Obfervation. In fuch Cafes, there- fore, it will be better to have the true Pofition of the Me- ridian, or the exacf time wherein the Star paffes the Meri- dian, in order either to place the Inftrument in zheMeridtan, or to obferve the Altitude of the Star the Moment it paffes the Meridian. See Altitude and Quadrant.

Tofndthe Meridian Altitude of the Sun, &c. hya Gno- mon. See Gnomon.

Meridional Diftance in Navigation, is the fame with the Departure; Eafling or Wetting 5 or the Difference of Longitude between the Meridian, under which the Ship now is, and any other Meridian fhe was under before. See Departure.

Meridional Parts, Miles, or Miiiutes, in Navigation, are the Parts, by which the Meridians in Mercator's Chm do increafe, as the Parallels of Latitude decreafe. See Chart.

The Co-fine of the Latitude of any Place being equal to the Radius, or Semi-diameter of that Parallel, there- fore in the true Sea-Chart, or Nautical Planifphere, this Radius being the Radius of the Equinoctial, or whole Sine of 00 Degrees, the Meridian Parts at each Degree of Latitude muft increafe, as the Secants of the Ark con- tain'd between that Latitude and the Equinoctial do decreafe.

The Tables therefore of Meridional Parts in Books of Navigation, are made by a continual addition of Se- cants, calculated in fome Books (as in Sir Jonas Moor's Tables) for every Degree and Minute of Latitude 3 and

C W )

MER

thefe will ferve either to make or graduate a Mereaior'i Chart, or to work the Macam's Sailing.

To ufc them, you mull enter the Table, with the De- gree 01 Latitude at the head, and with the Minute on the firft Column towards the Left-hand ; and in the Ancle of meeting, you will have the Meridional Parts.

Having the Latitudes of two Places, to find the Me- ridional MJti, or Mnmes between them : conftder whether the Places be, one under the Equinoflial, and the other wide thereof; or the one on the one fide the Equinoflial, and the other on the other ; or whether they both lie on the lame fide.

If one Place lie under the Equator, the Meridional Mi- nnies next under the Degree of Latitude of the other Place, is the Meridional difference of Latitude, or Latitude en- larged.

If one be in North, and the other in South Latitude ; the Meridional Minutes correiponding to the two Latitudes added together, give the Meridional Minutes between them.

Both Places lying rewards the fame Pole ; fubftraflthe Meridional Parts anlwering to the lefs Latitude from thole

"SlSTfSf lc' he r " I,iinder gives the Meridi m alMm,e„

MERIDIANS, or Meridian 1, a Name which the an- tient Romans gave 10 a kind of Gladiators, who enter'd the Jrau 1 about m»j alter the Eejtiani, who fought in the Morning againft Beads, had finilh'd. See Gladiator

1 he Mendiani fought Man with Man, Sword in hand' : Hence oe»«« takes occafion to obferve, that the Combats of the Morning were tull of Humanity, compared with thole which tollow'd.

The Meridians took their Name from Meridies i. e. Noon, the time when they exhibited their Shews

MERIT, in Theology, is ufed to fignity the Moral Goodnefs or the Aftions of Men, and the Reward due to them.

The Romi/h S.hoolmcn diflingui/h two kinds of Merit towards God : The one of Congruity, and the other of Gonaigmty.

1'he Merit ofCongruity, is, when there is no iuft Pro portion between the Action, and the Reward • but he who bellows the Reward fupplies by his Goodnefs or Li berality, whar was wanting in the ABion : Such is the Merit ot a Son towards his Father ; but this is only Merit in an improper fenfe.

The Merit of Condignity, is, when there is an abfolute Equality, and ajuit Euimation between the Adion and the Reward, as in the Wages ofa Workman.

Thofe of the Reformed Religion difclaim all Merit to- wards God. Even their bell Works don't Merit any thing at his hands. The Doarine of Merits makes one of the great Arncles of Controverfy between the Romi/h and Reformed Churches.

MERLON, in Fortification, that part of the Parapet which lies betwixt two Embrafures. See Parapet and Embrasure.

It is from 8 to 9 Foot long on the fide of the Can- non, and 6 on the tide of the Field j about 6 Foot high and 18 thick. b '

The Word comes from Merula, or Merla, which in the corrupt Latm was ufed for a Battlement.

MERMAID, or Merman, a Sea-Creature frequently talk'd of, as being fuppofed half human, and half a Fi/ri See Monster.

However Naturalifts may doubt of the Reality of Mer- men, ot Mermaids, yet we have Teftimony enough toefta* bhih it beyond all contradiftion. In the Year 1187 as Larrey informs us, fuch a Monfter was fifli'd up in 'the County of Suffolk, and kept by the Govemour for fix Months It bore fo near a Conformiry with Man, that nothing feem'd wanting to it befides Speech. One day it took the Opportunity of making its Efcape, and plunging into the Sea was never more heard of. Hifl. d' Angleterre, P. I. p. 40;. '

In rhe Year 1430, after a huge Tempelt, which broke down the Dykes in Holland, and made way for the Sea intu the Meadows,^, fome Girls of the Town of Edam mWeli- Friezland, going in a Boat to milk their Cows, perceiv'd a Mermaid embarrafs'd in the Mud, with a very little Water, They took it into their Boat, and brought it with them to Edam, drefs'd it in Women's Apparel, and taught it to fpin. It fed like one of them, but could never be'brought to fpcak. Some time afterwards it was brought to Haer- lem, where it liv'd for fome Years, tho' ftill° /hewing an Inclination to the Water. Partial relates, that they had given it fome Notion of a Deity, and that it made its Reverences very devoutly when ever it pafs'd by a Cru- cifix. Delices d' Hollande.

In the Year 1560, near the I/land of Mamr, on the

Weilern Coaft of the Illand of Ceylon, fome Filhers

brought up at one Draught of a Net, feven Mer-mea and

-Maids; of which, feveral Jefuits, and among the reft

X x x x x x F. lien.